Move to 'using namespace std;' in all .cpp files.
[movit] / effect_chain.cpp
index aae2941..d80c4f8 100644 (file)
 #define GL_GLEXT_PROTOTYPES 1
 
+#include <GL/glew.h>
+#include <assert.h>
+#include <locale.h>
+#include <math.h>
+#include <stddef.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
-#include <assert.h>
-
 #include <algorithm>
 #include <set>
 #include <stack>
 #include <vector>
 
-#include "util.h"
+#include "alpha_division_effect.h"
+#include "alpha_multiplication_effect.h"
+#include "colorspace_conversion_effect.h"
+#include "dither_effect.h"
+#include "effect.h"
 #include "effect_chain.h"
-#include "gamma_expansion_effect.h"
 #include "gamma_compression_effect.h"
-#include "colorspace_conversion_effect.h"
+#include "gamma_expansion_effect.h"
+#include "init.h"
 #include "input.h"
-#include "opengl.h"
+#include "resource_pool.h"
+#include "util.h"
 
-EffectChain::EffectChain(unsigned width, unsigned height)
-       : width(width),
-         height(height),
-         finalized(false) {}
+using namespace std;
+
+EffectChain::EffectChain(float aspect_nom, float aspect_denom, ResourcePool *resource_pool)
+       : aspect_nom(aspect_nom),
+         aspect_denom(aspect_denom),
+         dither_effect(NULL),
+         num_dither_bits(0),
+         finalized(false),
+         resource_pool(resource_pool) {
+       if (resource_pool == NULL) {
+               this->resource_pool = new ResourcePool();
+               owns_resource_pool = true;
+       } else {
+               owns_resource_pool = false;
+       }
+}
 
-Input *EffectChain::add_input(Input *input)
+EffectChain::~EffectChain()
 {
-       char eff_id[256];
-       sprintf(eff_id, "src_image%u", (unsigned)inputs.size());
+       for (unsigned i = 0; i < nodes.size(); ++i) {
+               delete nodes[i]->effect;
+               delete nodes[i];
+       }
+       for (unsigned i = 0; i < phases.size(); ++i) {
+               resource_pool->release_glsl_program(phases[i]->glsl_program_num);
+               delete phases[i];
+       }
+       if (owns_resource_pool) {
+               delete resource_pool;
+       }
+}
 
+Input *EffectChain::add_input(Input *input)
+{
+       assert(!finalized);
        inputs.push_back(input);
-
-       Node *node = new Node;
-       node->effect = input;
-       node->effect_id = eff_id;
-       node->output_color_space = input->get_color_space();
-       node->output_gamma_curve = input->get_gamma_curve();
-
-       nodes.push_back(node);
-       node_map[input] = node;
-
+       add_node(input);
        return input;
 }
 
-void EffectChain::add_output(const ImageFormat &format)
+void EffectChain::add_output(const ImageFormat &format, OutputAlphaFormat alpha_format)
 {
+       assert(!finalized);
        output_format = format;
+       output_alpha_format = alpha_format;
 }
 
-void EffectChain::add_effect_raw(Effect *effect, const std::vector<Effect *> &inputs)
+Node *EffectChain::add_node(Effect *effect)
 {
-       char effect_id[256];
-       sprintf(effect_id, "eff%u", (unsigned)nodes.size());
+       for (unsigned i = 0; i < nodes.size(); ++i) {
+               assert(nodes[i]->effect != effect);
+       }
 
        Node *node = new Node;
        node->effect = effect;
-       node->effect_id = effect_id;
-
-       assert(inputs.size() == effect->num_inputs());
-       assert(inputs.size() >= 1);
-       for (unsigned i = 0; i < inputs.size(); ++i) {
-               assert(node_map.count(inputs[i]) != 0);
-               node_map[inputs[i]]->outgoing_links.push_back(node);
-               node->incoming_links.push_back(node_map[inputs[i]]);
-               if (i == 0) {
-                       node->output_gamma_curve = node_map[inputs[i]]->output_gamma_curve;
-                       node->output_color_space = node_map[inputs[i]]->output_color_space;
-               } else {
-                       assert(node->output_gamma_curve == node_map[inputs[i]]->output_gamma_curve);
-                       assert(node->output_color_space == node_map[inputs[i]]->output_color_space);
-               }
-       }
+       node->disabled = false;
+       node->output_color_space = COLORSPACE_INVALID;
+       node->output_gamma_curve = GAMMA_INVALID;
+       node->output_alpha_type = ALPHA_INVALID;
 
        nodes.push_back(node);
        node_map[effect] = node;
+       effect->inform_added(this);
+       return node;
 }
 
-void EffectChain::find_all_nonlinear_inputs(Node *node,
-                                            std::vector<Node *> *nonlinear_inputs,
-                                            std::vector<Node *> *intermediates)
+void EffectChain::connect_nodes(Node *sender, Node *receiver)
 {
-       if (node->output_gamma_curve == GAMMA_LINEAR) {
-               return;
-       }
-       if (node->effect->num_inputs() == 0) {
-               nonlinear_inputs->push_back(node);
-       } else {
-               intermediates->push_back(node);
-               assert(node->effect->num_inputs() == node->incoming_links.size());
-               for (unsigned i = 0; i < node->incoming_links.size(); ++i) {
-                       find_all_nonlinear_inputs(node->incoming_links[i], nonlinear_inputs, intermediates);
-               }
-       }
+       sender->outgoing_links.push_back(receiver);
+       receiver->incoming_links.push_back(sender);
 }
 
-Node *EffectChain::normalize_to_linear_gamma(Node *input)
+void EffectChain::replace_receiver(Node *old_receiver, Node *new_receiver)
 {
-       // Find out if all the inputs can be set to deliver sRGB inputs.
-       // If so, we can just ask them to do that instead of inserting a
-       // (possibly expensive) conversion operation.
-       //
-       // NOTE: We assume that effects generally don't mess with the gamma
-       // curve (except GammaCompressionEffect, which should never be
-       // inserted into a chain when this is called), so that we can just
-       // update the output gamma as we go.
-       //
-       // TODO: Setting this flag for one source might confuse a different
-       // part of the pipeline using the same source.
-       std::vector<Node *> nonlinear_inputs;
-       std::vector<Node *> intermediates;
-       find_all_nonlinear_inputs(input, &nonlinear_inputs, &intermediates);
+       new_receiver->incoming_links = old_receiver->incoming_links;
+       old_receiver->incoming_links.clear();
+       
+       for (unsigned i = 0; i < new_receiver->incoming_links.size(); ++i) {
+               Node *sender = new_receiver->incoming_links[i];
+               for (unsigned j = 0; j < sender->outgoing_links.size(); ++j) {
+                       if (sender->outgoing_links[j] == old_receiver) {
+                               sender->outgoing_links[j] = new_receiver;
+                       }
+               }
+       }       
+}
 
-       bool all_ok = true;
-       for (unsigned i = 0; i < nonlinear_inputs.size(); ++i) {
-               Input *input = static_cast<Input *>(nonlinear_inputs[i]->effect);
-               all_ok &= input->can_output_linear_gamma();
-       }
+void EffectChain::replace_sender(Node *old_sender, Node *new_sender)
+{
+       new_sender->outgoing_links = old_sender->outgoing_links;
+       old_sender->outgoing_links.clear();
+       
+       for (unsigned i = 0; i < new_sender->outgoing_links.size(); ++i) {
+               Node *receiver = new_sender->outgoing_links[i];
+               for (unsigned j = 0; j < receiver->incoming_links.size(); ++j) {
+                       if (receiver->incoming_links[j] == old_sender) {
+                               receiver->incoming_links[j] = new_sender;
+                       }
+               }
+       }       
+}
 
-       if (all_ok) {
-               for (unsigned i = 0; i < nonlinear_inputs.size(); ++i) {
-                       bool ok = nonlinear_inputs[i]->effect->set_int("output_linear_gamma", 1);
-                       assert(ok);
-                       nonlinear_inputs[i]->output_gamma_curve = GAMMA_LINEAR;
+void EffectChain::insert_node_between(Node *sender, Node *middle, Node *receiver)
+{
+       for (unsigned i = 0; i < sender->outgoing_links.size(); ++i) {
+               if (sender->outgoing_links[i] == receiver) {
+                       sender->outgoing_links[i] = middle;
+                       middle->incoming_links.push_back(sender);
                }
-               for (unsigned i = 0; i < intermediates.size(); ++i) {
-                       intermediates[i]->output_gamma_curve = GAMMA_LINEAR;
+       }
+       for (unsigned i = 0; i < receiver->incoming_links.size(); ++i) {
+               if (receiver->incoming_links[i] == sender) {
+                       receiver->incoming_links[i] = middle;
+                       middle->outgoing_links.push_back(receiver);
                }
-               return input;
        }
 
-       // OK, that didn't work. Insert a conversion effect.
-       GammaExpansionEffect *gamma_conversion = new GammaExpansionEffect();
-       gamma_conversion->set_int("source_curve", input->output_gamma_curve);
-       std::vector<Effect *> inputs;
-       inputs.push_back(input->effect);
-       gamma_conversion->add_self_to_effect_chain(this, inputs);
-
-       assert(node_map.count(gamma_conversion) != 0);
-       Node *node = node_map[gamma_conversion];
-       node->output_gamma_curve = GAMMA_LINEAR;
-       return node;
+       assert(middle->incoming_links.size() == middle->effect->num_inputs());
 }
 
-Node *EffectChain::normalize_to_srgb(Node *input)
+void EffectChain::find_all_nonlinear_inputs(Node *node, vector<Node *> *nonlinear_inputs)
 {
-       assert(input->output_gamma_curve == GAMMA_LINEAR);
-       ColorSpaceConversionEffect *colorspace_conversion = new ColorSpaceConversionEffect();
-       colorspace_conversion->set_int("source_space", input->output_color_space);
-       colorspace_conversion->set_int("destination_space", COLORSPACE_sRGB);
-       std::vector<Effect *> inputs;
-       inputs.push_back(input->effect);
-       colorspace_conversion->add_self_to_effect_chain(this, inputs);
-
-       assert(node_map.count(colorspace_conversion) != 0);
-       Node *node = node_map[colorspace_conversion];
-       node->output_color_space = COLORSPACE_sRGB;
-       return node;
+       if (node->output_gamma_curve == GAMMA_LINEAR &&
+           node->effect->effect_type_id() != "GammaCompressionEffect") {
+               return;
+       }
+       if (node->effect->num_inputs() == 0) {
+               nonlinear_inputs->push_back(node);
+       } else {
+               assert(node->effect->num_inputs() == node->incoming_links.size());
+               for (unsigned i = 0; i < node->incoming_links.size(); ++i) {
+                       find_all_nonlinear_inputs(node->incoming_links[i], nonlinear_inputs);
+               }
+       }
 }
 
-Effect *EffectChain::add_effect(Effect *effect, const std::vector<Effect *> &inputs)
+Effect *EffectChain::add_effect(Effect *effect, const vector<Effect *> &inputs)
 {
+       assert(!finalized);
        assert(inputs.size() == effect->num_inputs());
-
-       std::vector<Effect *> normalized_inputs = inputs;
-       for (unsigned i = 0; i < normalized_inputs.size(); ++i) {
-               assert(node_map.count(normalized_inputs[i]) != 0);
-               Node *input = node_map[normalized_inputs[i]];
-               if (effect->needs_linear_light() && input->output_gamma_curve != GAMMA_LINEAR) {
-                       input = normalize_to_linear_gamma(input);
-               }
-               if (effect->needs_srgb_primaries() && input->output_color_space != COLORSPACE_sRGB) {
-                       input = normalize_to_srgb(input);
-               }
-               normalized_inputs[i] = input->effect;
+       Node *node = add_node(effect);
+       for (unsigned i = 0; i < inputs.size(); ++i) {
+               assert(node_map.count(inputs[i]) != 0);
+               connect_nodes(node_map[inputs[i]], node);
        }
-
-       effect->add_self_to_effect_chain(this, normalized_inputs);
        return effect;
 }
 
 // GLSL pre-1.30 doesn't support token pasting. Replace PREFIX(x) with <effect_id>_x.
-std::string replace_prefix(const std::string &text, const std::string &prefix)
+string replace_prefix(const string &text, const string &prefix)
 {
-       std::string output;
+       string output;
        size_t start = 0;
 
        while (start < text.size()) {
                size_t pos = text.find("PREFIX(", start);
-               if (pos == std::string::npos) {
-                       output.append(text.substr(start, std::string::npos));
+               if (pos == string::npos) {
+                       output.append(text.substr(start, string::npos));
                        break;
                }
 
@@ -219,47 +216,56 @@ std::string replace_prefix(const std::string &text, const std::string &prefix)
 }
 
 Phase *EffectChain::compile_glsl_program(
-       const std::vector<Node *> &inputs,
-       const std::vector<Node *> &effects)
+       const vector<Node *> &inputs,
+       const vector<Node *> &effects)
 {
+       Phase *phase = new Phase;
        assert(!effects.empty());
 
        // Deduplicate the inputs.
-       std::vector<Node *> true_inputs = inputs;
-       std::sort(true_inputs.begin(), true_inputs.end());
-       true_inputs.erase(std::unique(true_inputs.begin(), true_inputs.end()), true_inputs.end());
+       vector<Node *> true_inputs = inputs;
+       sort(true_inputs.begin(), true_inputs.end());
+       true_inputs.erase(unique(true_inputs.begin(), true_inputs.end()), true_inputs.end());
 
        bool input_needs_mipmaps = false;
-       std::string frag_shader = read_file("header.frag");
+       string frag_shader = read_file("header.frag");
 
        // Create functions for all the texture inputs that we need.
        for (unsigned i = 0; i < true_inputs.size(); ++i) {
                Node *input = true_inputs[i];
+               char effect_id[256];
+               sprintf(effect_id, "in%u", i);
+               phase->effect_ids.insert(make_pair(input, effect_id));
        
-               frag_shader += std::string("uniform sampler2D tex_") + input->effect_id + ";\n";
-               frag_shader += std::string("vec4 ") + input->effect_id + "(vec2 tc) {\n";
-               frag_shader += "\treturn texture2D(tex_" + input->effect_id + ", tc);\n";
+               frag_shader += string("uniform sampler2D tex_") + effect_id + ";\n";
+               frag_shader += string("vec4 ") + effect_id + "(vec2 tc) {\n";
+               frag_shader += "\treturn texture2D(tex_" + string(effect_id) + ", tc);\n";
                frag_shader += "}\n";
                frag_shader += "\n";
        }
 
-       for (unsigned i = 0; i < effects.size(); ++i) {
-               Node *node = effects[i];
+       vector<Node *> sorted_effects = topological_sort(effects);
+
+       for (unsigned i = 0; i < sorted_effects.size(); ++i) {
+               Node *node = sorted_effects[i];
+               char effect_id[256];
+               sprintf(effect_id, "eff%u", i);
+               phase->effect_ids.insert(make_pair(node, effect_id));
 
                if (node->incoming_links.size() == 1) {
-                       frag_shader += std::string("#define INPUT ") + node->incoming_links[0]->effect_id + "\n";
+                       frag_shader += string("#define INPUT ") + phase->effect_ids[node->incoming_links[0]] + "\n";
                } else {
                        for (unsigned j = 0; j < node->incoming_links.size(); ++j) {
                                char buf[256];
-                               sprintf(buf, "#define INPUT%d %s\n", j + 1, node->incoming_links[j]->effect_id.c_str());
+                               sprintf(buf, "#define INPUT%d %s\n", j + 1, phase->effect_ids[node->incoming_links[j]].c_str());
                                frag_shader += buf;
                        }
                }
        
                frag_shader += "\n";
-               frag_shader += std::string("#define FUNCNAME ") + node->effect_id + "\n";
-               frag_shader += replace_prefix(node->effect->output_convenience_uniforms(), node->effect_id);
-               frag_shader += replace_prefix(node->effect->output_fragment_shader(), node->effect_id);
+               frag_shader += string("#define FUNCNAME ") + effect_id + "\n";
+               frag_shader += replace_prefix(node->effect->output_convenience_uniforms(), effect_id);
+               frag_shader += replace_prefix(node->effect->output_fragment_shader(), effect_id);
                frag_shader += "#undef PREFIX\n";
                frag_shader += "#undef FUNCNAME\n";
                if (node->incoming_links.size() == 1) {
@@ -275,31 +281,19 @@ Phase *EffectChain::compile_glsl_program(
 
                input_needs_mipmaps |= node->effect->needs_mipmaps();
        }
-       for (unsigned i = 0; i < effects.size(); ++i) {
-               Node *node = effects[i];
+       for (unsigned i = 0; i < sorted_effects.size(); ++i) {
+               Node *node = sorted_effects[i];
                if (node->effect->num_inputs() == 0) {
-                       node->effect->set_int("needs_mipmaps", input_needs_mipmaps);
+                       CHECK(node->effect->set_int("needs_mipmaps", input_needs_mipmaps));
                }
        }
-       frag_shader += std::string("#define INPUT ") + effects.back()->effect_id + "\n";
+       frag_shader += string("#define INPUT ") + phase->effect_ids[sorted_effects.back()] + "\n";
        frag_shader.append(read_file("footer.frag"));
-       printf("%s\n", frag_shader.c_str());
-       
-       GLuint glsl_program_num = glCreateProgram();
-       GLuint vs_obj = compile_shader(read_file("vs.vert"), GL_VERTEX_SHADER);
-       GLuint fs_obj = compile_shader(frag_shader, GL_FRAGMENT_SHADER);
-       glAttachShader(glsl_program_num, vs_obj);
-       check_error();
-       glAttachShader(glsl_program_num, fs_obj);
-       check_error();
-       glLinkProgram(glsl_program_num);
-       check_error();
 
-       Phase *phase = new Phase;
-       phase->glsl_program_num = glsl_program_num;
+       phase->glsl_program_num = resource_pool->compile_glsl_program(read_file("vs.vert"), frag_shader);
        phase->input_needs_mipmaps = input_needs_mipmaps;
        phase->inputs = true_inputs;
-       phase->effects = effects;
+       phase->effects = sorted_effects;
 
        return phase;
 }
@@ -314,25 +308,25 @@ Phase *EffectChain::compile_glsl_program(
 // without any explicit recursion.
 void EffectChain::construct_glsl_programs(Node *output)
 {
-       // Which effects have already been completed in this phase?
+       // Which effects have already been completed?
        // We need to keep track of it, as an effect with multiple outputs
-       // could otherwise be calculate multiple times.
-       std::set<Node *> completed_effects;
+       // could otherwise be calculated multiple times.
+       set<Node *> completed_effects;
 
        // Effects in the current phase, as well as inputs (outputs from other phases
        // that we depend on). Note that since we start iterating from the end,
        // the effect list will be in the reverse order.
-       std::vector<Node *> this_phase_inputs;
-       std::vector<Node *> this_phase_effects;
+       vector<Node *> this_phase_inputs;
+       vector<Node *> this_phase_effects;
 
        // Effects that we have yet to calculate, but that we know should
        // be in the current phase.
-       std::stack<Node *> effects_todo_this_phase;
+       stack<Node *> effects_todo_this_phase;
 
        // Effects that we have yet to calculate, but that come from other phases.
        // We delay these until we have this phase done in its entirety,
        // at which point we pick any of them and start a new phase from that.
-       std::stack<Node *> effects_todo_other_phases;
+       stack<Node *> effects_todo_other_phases;
 
        effects_todo_this_phase.push(output);
 
@@ -342,15 +336,22 @@ void EffectChain::construct_glsl_programs(Node *output)
                        Node *node = effects_todo_this_phase.top();
                        effects_todo_this_phase.pop();
 
-                       // This should currently only happen for effects that are phase outputs,
-                       // and we throw those out separately below.
-                       assert(completed_effects.count(node) == 0);
+                       // This should currently only happen for effects that are inputs
+                       // (either true inputs or phase outputs). We special-case inputs,
+                       // and then deduplicate phase outputs in compile_glsl_program().
+                       if (node->effect->num_inputs() == 0) {
+                               if (find(this_phase_effects.begin(), this_phase_effects.end(), node) != this_phase_effects.end()) {
+                                       continue;
+                               }
+                       } else {
+                               assert(completed_effects.count(node) == 0);
+                       }
 
                        this_phase_effects.push_back(node);
                        completed_effects.insert(node);
 
                        // Find all the dependencies of this effect, and add them to the stack.
-                       std::vector<Node *> deps = node->incoming_links;
+                       vector<Node *> deps = node->incoming_links;
                        assert(node->effect->num_inputs() == deps.size());
                        for (unsigned i = 0; i < deps.size(); ++i) {
                                bool start_new_phase = false;
@@ -360,13 +361,27 @@ void EffectChain::construct_glsl_programs(Node *output)
                                        start_new_phase = true;
                                }
 
-                               if (deps[i]->outgoing_links.size() > 1 && deps[i]->effect->num_inputs() > 0) {
-                                       // More than one effect uses this as the input,
-                                       // and it is not a texture itself.
-                                       // The easiest thing to do (and probably also the safest
-                                       // performance-wise in most cases) is to bounce it to a texture
-                                       // and then let the next passes read from that.
-                                       start_new_phase = true;
+                               if (deps[i]->outgoing_links.size() > 1) {
+                                       if (deps[i]->effect->num_inputs() > 0) {
+                                               // More than one effect uses this as the input,
+                                               // and it is not a texture itself.
+                                               // The easiest thing to do (and probably also the safest
+                                               // performance-wise in most cases) is to bounce it to a texture
+                                               // and then let the next passes read from that.
+                                               start_new_phase = true;
+                                       } else {
+                                               // For textures, we try to be slightly more clever;
+                                               // if none of our outputs need a bounce, we don't bounce
+                                               // but instead simply use the effect many times.
+                                               //
+                                               // Strictly speaking, we could bounce it for some outputs
+                                               // and use it directly for others, but the processing becomes
+                                               // somewhat simpler if the effect is only used in one such way.
+                                               for (unsigned j = 0; j < deps[i]->outgoing_links.size(); ++j) {
+                                                       Node *rdep = deps[i]->outgoing_links[j];
+                                                       start_new_phase |= rdep->effect->needs_texture_bounce();
+                                               }
+                                       }
                                }
 
                                if (deps[i]->effect->changes_output_size()) {
@@ -411,11 +426,15 @@ void EffectChain::construct_glsl_programs(Node *output)
 
        // Finally, since the phases are found from the output but must be executed
        // from the input(s), reverse them, too.
-       std::reverse(phases.begin(), phases.end());
+       reverse(phases.begin(), phases.end());
 }
 
 void EffectChain::output_dot(const char *filename)
 {
+       if (movit_debug_level != MOVIT_DEBUG_ON) {
+               return;
+       }
+
        FILE *fp = fopen(filename, "w");
        if (fp == NULL) {
                perror(filename);
@@ -423,169 +442,976 @@ void EffectChain::output_dot(const char *filename)
        }
 
        fprintf(fp, "digraph G {\n");
+       fprintf(fp, "  output [shape=box label=\"(output)\"];\n");
        for (unsigned i = 0; i < nodes.size(); ++i) {
-               fprintf(fp, "  n%ld [label=\"%s\"];\n", (long)nodes[i], nodes[i]->effect->effect_type_id().c_str());
+               // Find out which phase this event belongs to.
+               vector<int> in_phases;
+               for (unsigned j = 0; j < phases.size(); ++j) {
+                       const Phase* p = phases[j];
+                       if (find(p->effects.begin(), p->effects.end(), nodes[i]) != p->effects.end()) {
+                               in_phases.push_back(j);
+                       }
+               }
+
+               if (in_phases.empty()) {
+                       fprintf(fp, "  n%ld [label=\"%s\"];\n", (long)nodes[i], nodes[i]->effect->effect_type_id().c_str());
+               } else if (in_phases.size() == 1) {
+                       fprintf(fp, "  n%ld [label=\"%s\" style=\"filled\" fillcolor=\"/accent8/%d\"];\n",
+                               (long)nodes[i], nodes[i]->effect->effect_type_id().c_str(),
+                               (in_phases[0] % 8) + 1);
+               } else {
+                       // If we had new enough Graphviz, style="wedged" would probably be ideal here.
+                       // But alas.
+                       fprintf(fp, "  n%ld [label=\"%s [in multiple phases]\" style=\"filled\" fillcolor=\"/accent8/%d\"];\n",
+                               (long)nodes[i], nodes[i]->effect->effect_type_id().c_str(),
+                               (in_phases[0] % 8) + 1);
+               }
+
+               char from_node_id[256];
+               snprintf(from_node_id, 256, "n%ld", (long)nodes[i]);
+
                for (unsigned j = 0; j < nodes[i]->outgoing_links.size(); ++j) {
-                       std::vector<std::string> labels;
+                       char to_node_id[256];
+                       snprintf(to_node_id, 256, "n%ld", (long)nodes[i]->outgoing_links[j]);
 
-                       if (nodes[i]->outgoing_links[j]->effect->needs_texture_bounce()) {
-                               labels.push_back("needs_bounce");
-                       }
-                       if (nodes[i]->effect->changes_output_size()) {
-                               labels.push_back("resize");
+                       vector<string> labels = get_labels_for_edge(nodes[i], nodes[i]->outgoing_links[j]);
+                       output_dot_edge(fp, from_node_id, to_node_id, labels);
+               }
+
+               if (nodes[i]->outgoing_links.empty() && !nodes[i]->disabled) {
+                       // Output node.
+                       vector<string> labels = get_labels_for_edge(nodes[i], NULL);
+                       output_dot_edge(fp, from_node_id, "output", labels);
+               }
+       }
+       fprintf(fp, "}\n");
+
+       fclose(fp);
+}
+
+vector<string> EffectChain::get_labels_for_edge(const Node *from, const Node *to)
+{
+       vector<string> labels;
+
+       if (to != NULL && to->effect->needs_texture_bounce()) {
+               labels.push_back("needs_bounce");
+       }
+       if (from->effect->changes_output_size()) {
+               labels.push_back("resize");
+       }
+
+       switch (from->output_color_space) {
+       case COLORSPACE_INVALID:
+               labels.push_back("spc[invalid]");
+               break;
+       case COLORSPACE_REC_601_525:
+               labels.push_back("spc[rec601-525]");
+               break;
+       case COLORSPACE_REC_601_625:
+               labels.push_back("spc[rec601-625]");
+               break;
+       default:
+               break;
+       }
+
+       switch (from->output_gamma_curve) {
+       case GAMMA_INVALID:
+               labels.push_back("gamma[invalid]");
+               break;
+       case GAMMA_sRGB:
+               labels.push_back("gamma[sRGB]");
+               break;
+       case GAMMA_REC_601:  // and GAMMA_REC_709
+               labels.push_back("gamma[rec601/709]");
+               break;
+       default:
+               break;
+       }
+
+       switch (from->output_alpha_type) {
+       case ALPHA_INVALID:
+               labels.push_back("alpha[invalid]");
+               break;
+       case ALPHA_BLANK:
+               labels.push_back("alpha[blank]");
+               break;
+       case ALPHA_POSTMULTIPLIED:
+               labels.push_back("alpha[postmult]");
+               break;
+       default:
+               break;
+       }
+
+       return labels;
+}
+
+void EffectChain::output_dot_edge(FILE *fp,
+                                  const string &from_node_id,
+                                  const string &to_node_id,
+                                  const vector<string> &labels)
+{
+       if (labels.empty()) {
+               fprintf(fp, "  %s -> %s;\n", from_node_id.c_str(), to_node_id.c_str());
+       } else {
+               string label = labels[0];
+               for (unsigned k = 1; k < labels.size(); ++k) {
+                       label += ", " + labels[k];
+               }
+               fprintf(fp, "  %s -> %s [label=\"%s\"];\n", from_node_id.c_str(), to_node_id.c_str(), label.c_str());
+       }
+}
+
+void EffectChain::size_rectangle_to_fit(unsigned width, unsigned height, unsigned *output_width, unsigned *output_height)
+{
+       unsigned scaled_width, scaled_height;
+
+       if (float(width) * aspect_denom >= float(height) * aspect_nom) {
+               // Same aspect, or W/H > aspect (image is wider than the frame).
+               // In either case, keep width, and adjust height.
+               scaled_width = width;
+               scaled_height = lrintf(width * aspect_denom / aspect_nom);
+       } else {
+               // W/H < aspect (image is taller than the frame), so keep height,
+               // and adjust width.
+               scaled_width = lrintf(height * aspect_nom / aspect_denom);
+               scaled_height = height;
+       }
+
+       // We should be consistently larger or smaller then the existing choice,
+       // since we have the same aspect.
+       assert(!(scaled_width < *output_width && scaled_height > *output_height));
+       assert(!(scaled_height < *output_height && scaled_width > *output_width));
+
+       if (scaled_width >= *output_width && scaled_height >= *output_height) {
+               *output_width = scaled_width;
+               *output_height = scaled_height;
+       }
+}
+
+// Propagate input texture sizes throughout, and inform effects downstream.
+// (Like a lot of other code, we depend on effects being in topological order.)
+void EffectChain::inform_input_sizes(Phase *phase)
+{
+       // All effects that have a defined size (inputs and RTT inputs)
+       // get that. Reset all others.
+       for (unsigned i = 0; i < phase->effects.size(); ++i) {
+               Node *node = phase->effects[i];
+               if (node->effect->num_inputs() == 0) {
+                       Input *input = static_cast<Input *>(node->effect);
+                       node->output_width = input->get_width();
+                       node->output_height = input->get_height();
+                       assert(node->output_width != 0);
+                       assert(node->output_height != 0);
+               } else {
+                       node->output_width = node->output_height = 0;
+               }
+       }
+       for (unsigned i = 0; i < phase->inputs.size(); ++i) {
+               Node *input = phase->inputs[i];
+               input->output_width = input->phase->virtual_output_width;
+               input->output_height = input->phase->virtual_output_height;
+               assert(input->output_width != 0);
+               assert(input->output_height != 0);
+       }
+
+       // Now propagate from the inputs towards the end, and inform as we go.
+       // The rules are simple:
+       //
+       //   1. Don't touch effects that already have given sizes (ie., inputs).
+       //   2. If all of your inputs have the same size, that will be your output size.
+       //   3. Otherwise, your output size is 0x0.
+       for (unsigned i = 0; i < phase->effects.size(); ++i) {
+               Node *node = phase->effects[i];
+               if (node->effect->num_inputs() == 0) {
+                       continue;
+               }
+               unsigned this_output_width = 0;
+               unsigned this_output_height = 0;
+               for (unsigned j = 0; j < node->incoming_links.size(); ++j) {
+                       Node *input = node->incoming_links[j];
+                       node->effect->inform_input_size(j, input->output_width, input->output_height);
+                       if (j == 0) {
+                               this_output_width = input->output_width;
+                               this_output_height = input->output_height;
+                       } else if (input->output_width != this_output_width || input->output_height != this_output_height) {
+                               // Inputs disagree.
+                               this_output_width = 0;
+                               this_output_height = 0;
                        }
+               }
+               node->output_width = this_output_width;
+               node->output_height = this_output_height;
+       }
+}
+
+// Note: You should call inform_input_sizes() before this, as the last effect's
+// desired output size might change based on the inputs.
+void EffectChain::find_output_size(Phase *phase)
+{
+       Node *output_node = phase->effects.back();
+
+       // If the last effect explicitly sets an output size, use that.
+       if (output_node->effect->changes_output_size()) {
+               output_node->effect->get_output_size(&phase->output_width, &phase->output_height,
+                                                    &phase->virtual_output_width, &phase->virtual_output_height);
+               return;
+       }
+
+       // If all effects have the same size, use that.
+       unsigned output_width = 0, output_height = 0;
+       bool all_inputs_same_size = true;
+
+       for (unsigned i = 0; i < phase->inputs.size(); ++i) {
+               Node *input = phase->inputs[i];
+               assert(input->phase->output_width != 0);
+               assert(input->phase->output_height != 0);
+               if (output_width == 0 && output_height == 0) {
+                       output_width = input->phase->virtual_output_width;
+                       output_height = input->phase->virtual_output_height;
+               } else if (output_width != input->phase->virtual_output_width ||
+                          output_height != input->phase->virtual_output_height) {
+                       all_inputs_same_size = false;
+               }
+       }
+       for (unsigned i = 0; i < phase->effects.size(); ++i) {
+               Effect *effect = phase->effects[i]->effect;
+               if (effect->num_inputs() != 0) {
+                       continue;
+               }
+
+               Input *input = static_cast<Input *>(effect);
+               if (output_width == 0 && output_height == 0) {
+                       output_width = input->get_width();
+                       output_height = input->get_height();
+               } else if (output_width != input->get_width() ||
+                          output_height != input->get_height()) {
+                       all_inputs_same_size = false;
+               }
+       }
+
+       if (all_inputs_same_size) {
+               assert(output_width != 0);
+               assert(output_height != 0);
+               phase->virtual_output_width = phase->output_width = output_width;
+               phase->virtual_output_height = phase->output_height = output_height;
+               return;
+       }
+
+       // If not, fit all the inputs into the current aspect, and select the largest one. 
+       output_width = 0;
+       output_height = 0;
+       for (unsigned i = 0; i < phase->inputs.size(); ++i) {
+               Node *input = phase->inputs[i];
+               assert(input->phase->output_width != 0);
+               assert(input->phase->output_height != 0);
+               size_rectangle_to_fit(input->phase->output_width, input->phase->output_height, &output_width, &output_height);
+       }
+       for (unsigned i = 0; i < phase->effects.size(); ++i) {
+               Effect *effect = phase->effects[i]->effect;
+               if (effect->num_inputs() != 0) {
+                       continue;
+               }
+
+               Input *input = static_cast<Input *>(effect);
+               size_rectangle_to_fit(input->get_width(), input->get_height(), &output_width, &output_height);
+       }
+       assert(output_width != 0);
+       assert(output_height != 0);
+       phase->virtual_output_width = phase->output_width = output_width;
+       phase->virtual_output_height = phase->output_height = output_height;
+}
+
+void EffectChain::sort_all_nodes_topologically()
+{
+       nodes = topological_sort(nodes);
+}
+
+vector<Node *> EffectChain::topological_sort(const vector<Node *> &nodes)
+{
+       set<Node *> nodes_left_to_visit(nodes.begin(), nodes.end());
+       vector<Node *> sorted_list;
+       for (unsigned i = 0; i < nodes.size(); ++i) {
+               topological_sort_visit_node(nodes[i], &nodes_left_to_visit, &sorted_list);
+       }
+       reverse(sorted_list.begin(), sorted_list.end());
+       return sorted_list;
+}
+
+void EffectChain::topological_sort_visit_node(Node *node, set<Node *> *nodes_left_to_visit, vector<Node *> *sorted_list)
+{
+       if (nodes_left_to_visit->count(node) == 0) {
+               return;
+       }
+       nodes_left_to_visit->erase(node);
+       for (unsigned i = 0; i < node->outgoing_links.size(); ++i) {
+               topological_sort_visit_node(node->outgoing_links[i], nodes_left_to_visit, sorted_list);
+       }
+       sorted_list->push_back(node);
+}
 
-                       switch (nodes[i]->output_color_space) {
-                       case COLORSPACE_REC_601_525:
-                               labels.push_back("spc[rec601-525]");
+void EffectChain::find_color_spaces_for_inputs()
+{
+       for (unsigned i = 0; i < nodes.size(); ++i) {
+               Node *node = nodes[i];
+               if (node->disabled) {
+                       continue;
+               }
+               if (node->incoming_links.size() == 0) {
+                       Input *input = static_cast<Input *>(node->effect);
+                       node->output_color_space = input->get_color_space();
+                       node->output_gamma_curve = input->get_gamma_curve();
+
+                       Effect::AlphaHandling alpha_handling = input->alpha_handling();
+                       switch (alpha_handling) {
+                       case Effect::OUTPUT_BLANK_ALPHA:
+                               node->output_alpha_type = ALPHA_BLANK;
                                break;
-                       case COLORSPACE_REC_601_625:
-                               labels.push_back("spc[rec601-625]");
+                       case Effect::INPUT_AND_OUTPUT_PREMULTIPLIED_ALPHA:
+                               node->output_alpha_type = ALPHA_PREMULTIPLIED;
                                break;
-                       default:
+                       case Effect::OUTPUT_POSTMULTIPLIED_ALPHA:
+                               node->output_alpha_type = ALPHA_POSTMULTIPLIED;
                                break;
+                       case Effect::INPUT_PREMULTIPLIED_ALPHA_KEEP_BLANK:
+                       case Effect::DONT_CARE_ALPHA_TYPE:
+                       default:
+                               assert(false);
                        }
 
-                       switch (nodes[i]->output_gamma_curve) {
-                       case GAMMA_sRGB:
-                               labels.push_back("gamma[sRGB]");
+                       if (node->output_alpha_type == ALPHA_PREMULTIPLIED) {
+                               assert(node->output_gamma_curve == GAMMA_LINEAR);
+                       }
+               }
+       }
+}
+
+// Propagate gamma and color space information as far as we can in the graph.
+// The rules are simple: Anything where all the inputs agree, get that as
+// output as well. Anything else keeps having *_INVALID.
+void EffectChain::propagate_gamma_and_color_space()
+{
+       // We depend on going through the nodes in order.
+       sort_all_nodes_topologically();
+
+       for (unsigned i = 0; i < nodes.size(); ++i) {
+               Node *node = nodes[i];
+               if (node->disabled) {
+                       continue;
+               }
+               assert(node->incoming_links.size() == node->effect->num_inputs());
+               if (node->incoming_links.size() == 0) {
+                       assert(node->output_color_space != COLORSPACE_INVALID);
+                       assert(node->output_gamma_curve != GAMMA_INVALID);
+                       continue;
+               }
+
+               Colorspace color_space = node->incoming_links[0]->output_color_space;
+               GammaCurve gamma_curve = node->incoming_links[0]->output_gamma_curve;
+               for (unsigned j = 1; j < node->incoming_links.size(); ++j) {
+                       if (node->incoming_links[j]->output_color_space != color_space) {
+                               color_space = COLORSPACE_INVALID;
+                       }
+                       if (node->incoming_links[j]->output_gamma_curve != gamma_curve) {
+                               gamma_curve = GAMMA_INVALID;
+                       }
+               }
+
+               // The conversion effects already have their outputs set correctly,
+               // so leave them alone.
+               if (node->effect->effect_type_id() != "ColorspaceConversionEffect") {
+                       node->output_color_space = color_space;
+               }               
+               if (node->effect->effect_type_id() != "GammaCompressionEffect" &&
+                   node->effect->effect_type_id() != "GammaExpansionEffect") {
+                       node->output_gamma_curve = gamma_curve;
+               }               
+       }
+}
+
+// Propagate alpha information as far as we can in the graph.
+// Similar to propagate_gamma_and_color_space().
+void EffectChain::propagate_alpha()
+{
+       // We depend on going through the nodes in order.
+       sort_all_nodes_topologically();
+
+       for (unsigned i = 0; i < nodes.size(); ++i) {
+               Node *node = nodes[i];
+               if (node->disabled) {
+                       continue;
+               }
+               assert(node->incoming_links.size() == node->effect->num_inputs());
+               if (node->incoming_links.size() == 0) {
+                       assert(node->output_alpha_type != ALPHA_INVALID);
+                       continue;
+               }
+
+               // The alpha multiplication/division effects are special cases.
+               if (node->effect->effect_type_id() == "AlphaMultiplicationEffect") {
+                       assert(node->incoming_links.size() == 1);
+                       assert(node->incoming_links[0]->output_alpha_type == ALPHA_POSTMULTIPLIED);
+                       node->output_alpha_type = ALPHA_PREMULTIPLIED;
+                       continue;
+               }
+               if (node->effect->effect_type_id() == "AlphaDivisionEffect") {
+                       assert(node->incoming_links.size() == 1);
+                       assert(node->incoming_links[0]->output_alpha_type == ALPHA_PREMULTIPLIED);
+                       node->output_alpha_type = ALPHA_POSTMULTIPLIED;
+                       continue;
+               }
+
+               // GammaCompressionEffect and GammaExpansionEffect are also a special case,
+               // because they are the only one that _need_ postmultiplied alpha.
+               if (node->effect->effect_type_id() == "GammaCompressionEffect" ||
+                   node->effect->effect_type_id() == "GammaExpansionEffect") {
+                       assert(node->incoming_links.size() == 1);
+                       if (node->incoming_links[0]->output_alpha_type == ALPHA_BLANK) {
+                               node->output_alpha_type = ALPHA_BLANK;
+                       } else if (node->incoming_links[0]->output_alpha_type == ALPHA_POSTMULTIPLIED) {
+                               node->output_alpha_type = ALPHA_POSTMULTIPLIED;
+                       } else {
+                               node->output_alpha_type = ALPHA_INVALID;
+                       }
+                       continue;
+               }
+
+               // Only inputs can have unconditional alpha output (OUTPUT_BLANK_ALPHA
+               // or OUTPUT_POSTMULTIPLIED_ALPHA), and they have already been
+               // taken care of above. Rationale: Even if you could imagine
+               // e.g. an effect that took in an image and set alpha=1.0
+               // unconditionally, it wouldn't make any sense to have it as
+               // e.g. OUTPUT_BLANK_ALPHA, since it wouldn't know whether it
+               // got its input pre- or postmultiplied, so it wouldn't know
+               // whether to divide away the old alpha or not.
+               Effect::AlphaHandling alpha_handling = node->effect->alpha_handling();
+               assert(alpha_handling == Effect::INPUT_AND_OUTPUT_PREMULTIPLIED_ALPHA ||
+                      alpha_handling == Effect::INPUT_PREMULTIPLIED_ALPHA_KEEP_BLANK ||
+                      alpha_handling == Effect::DONT_CARE_ALPHA_TYPE);
+
+               // If the node has multiple inputs, check that they are all valid and
+               // the same.
+               bool any_invalid = false;
+               bool any_premultiplied = false;
+               bool any_postmultiplied = false;
+
+               for (unsigned j = 0; j < node->incoming_links.size(); ++j) {
+                       switch (node->incoming_links[j]->output_alpha_type) {
+                       case ALPHA_INVALID:
+                               any_invalid = true;
                                break;
-                       case GAMMA_REC_601:  // and GAMMA_REC_709
-                               labels.push_back("gamma[rec601/709]");
+                       case ALPHA_BLANK:
+                               // Blank is good as both pre- and postmultiplied alpha,
+                               // so just ignore it.
                                break;
-                       default:
+                       case ALPHA_PREMULTIPLIED:
+                               any_premultiplied = true;
+                               break;
+                       case ALPHA_POSTMULTIPLIED:
+                               any_postmultiplied = true;
                                break;
+                       default:
+                               assert(false);
                        }
+               }
 
-                       if (labels.empty()) {
-                               fprintf(fp, "  n%ld -> n%ld;\n", (long)nodes[i], (long)nodes[i]->outgoing_links[j]);
+               if (any_invalid) {
+                       node->output_alpha_type = ALPHA_INVALID;
+                       continue;
+               }
+
+               // Inputs must be of the same type.
+               if (any_premultiplied && any_postmultiplied) {
+                       node->output_alpha_type = ALPHA_INVALID;
+                       continue;
+               }
+
+               if (alpha_handling == Effect::INPUT_AND_OUTPUT_PREMULTIPLIED_ALPHA ||
+                   alpha_handling == Effect::INPUT_PREMULTIPLIED_ALPHA_KEEP_BLANK) {
+                       // If the effect has asked for premultiplied alpha, check that it has got it.
+                       if (any_postmultiplied) {
+                               node->output_alpha_type = ALPHA_INVALID;
+                       } else if (!any_premultiplied &&
+                                  alpha_handling == Effect::INPUT_PREMULTIPLIED_ALPHA_KEEP_BLANK) {
+                               // Blank input alpha, and the effect preserves blank alpha.
+                               node->output_alpha_type = ALPHA_BLANK;
+                       } else {
+                               node->output_alpha_type = ALPHA_PREMULTIPLIED;
+                       }
+               } else {
+                       // OK, all inputs are the same, and this effect is not going
+                       // to change it.
+                       assert(alpha_handling == Effect::DONT_CARE_ALPHA_TYPE);
+                       if (any_premultiplied) {
+                               node->output_alpha_type = ALPHA_PREMULTIPLIED;
+                       } else if (any_postmultiplied) {
+                               node->output_alpha_type = ALPHA_POSTMULTIPLIED;
                        } else {
-                               std::string label = labels[0];
-                               for (unsigned k = 1; k < labels.size(); ++k) {
-                                       label += ", " + labels[k];
+                               node->output_alpha_type = ALPHA_BLANK;
+                       }
+               }
+       }
+}
+
+bool EffectChain::node_needs_colorspace_fix(Node *node)
+{
+       if (node->disabled) {
+               return false;
+       }
+       if (node->effect->num_inputs() == 0) {
+               return false;
+       }
+
+       // propagate_gamma_and_color_space() has already set our output
+       // to COLORSPACE_INVALID if the inputs differ, so we can rely on that.
+       if (node->output_color_space == COLORSPACE_INVALID) {
+               return true;
+       }
+       return (node->effect->needs_srgb_primaries() && node->output_color_space != COLORSPACE_sRGB);
+}
+
+// Fix up color spaces so that there are no COLORSPACE_INVALID nodes left in
+// the graph. Our strategy is not always optimal, but quite simple:
+// Find an effect that's as early as possible where the inputs are of
+// unacceptable colorspaces (that is, either different, or, if the effect only
+// wants sRGB, not sRGB.) Add appropriate conversions on all its inputs,
+// propagate the information anew, and repeat until there are no more such
+// effects.
+void EffectChain::fix_internal_color_spaces()
+{
+       unsigned colorspace_propagation_pass = 0;
+       bool found_any;
+       do {
+               found_any = false;
+               for (unsigned i = 0; i < nodes.size(); ++i) {
+                       Node *node = nodes[i];
+                       if (!node_needs_colorspace_fix(node)) {
+                               continue;
+                       }
+
+                       // Go through each input that is not sRGB, and insert
+                       // a colorspace conversion after it.
+                       for (unsigned j = 0; j < node->incoming_links.size(); ++j) {
+                               Node *input = node->incoming_links[j];
+                               assert(input->output_color_space != COLORSPACE_INVALID);
+                               if (input->output_color_space == COLORSPACE_sRGB) {
+                                       continue;
                                }
-                               fprintf(fp, "  n%ld -> n%ld [label=\"%s\"];\n", (long)nodes[i], (long)nodes[i]->outgoing_links[j], label.c_str());
+                               Node *conversion = add_node(new ColorspaceConversionEffect());
+                               CHECK(conversion->effect->set_int("source_space", input->output_color_space));
+                               CHECK(conversion->effect->set_int("destination_space", COLORSPACE_sRGB));
+                               conversion->output_color_space = COLORSPACE_sRGB;
+                               replace_sender(input, conversion);
+                               connect_nodes(input, conversion);
                        }
+
+                       // Re-sort topologically, and propagate the new information.
+                       propagate_gamma_and_color_space();
+                       
+                       found_any = true;
+                       break;
+               }
+       
+               char filename[256];
+               sprintf(filename, "step5-colorspacefix-iter%u.dot", ++colorspace_propagation_pass);
+               output_dot(filename);
+               assert(colorspace_propagation_pass < 100);
+       } while (found_any);
+
+       for (unsigned i = 0; i < nodes.size(); ++i) {
+               Node *node = nodes[i];
+               if (node->disabled) {
+                       continue;
                }
+               assert(node->output_color_space != COLORSPACE_INVALID);
        }
-       fprintf(fp, "}\n");
+}
 
-       fclose(fp);
+bool EffectChain::node_needs_alpha_fix(Node *node)
+{
+       if (node->disabled) {
+               return false;
+       }
+
+       // propagate_alpha() has already set our output to ALPHA_INVALID if the
+       // inputs differ or we are otherwise in mismatch, so we can rely on that.
+       return (node->output_alpha_type == ALPHA_INVALID);
 }
 
-void EffectChain::find_output_size(Phase *phase)
+// Fix up alpha so that there are no ALPHA_INVALID nodes left in
+// the graph. Similar to fix_internal_color_spaces().
+void EffectChain::fix_internal_alpha(unsigned step)
 {
-       Node *output_node = phase->effects.back();
+       unsigned alpha_propagation_pass = 0;
+       bool found_any;
+       do {
+               found_any = false;
+               for (unsigned i = 0; i < nodes.size(); ++i) {
+                       Node *node = nodes[i];
+                       if (!node_needs_alpha_fix(node)) {
+                               continue;
+                       }
 
-       // If the last effect explicitly sets an output size,
-       // use that.
-       if (output_node->effect->changes_output_size()) {
-               output_node->effect->get_output_size(&phase->output_width, &phase->output_height);
+                       // If we need to fix up GammaExpansionEffect, then clearly something
+                       // is wrong, since the combination of premultiplied alpha and nonlinear inputs
+                       // is meaningless.
+                       assert(node->effect->effect_type_id() != "GammaExpansionEffect");
+
+                       AlphaType desired_type = ALPHA_PREMULTIPLIED;
+
+                       // GammaCompressionEffect is special; it needs postmultiplied alpha.
+                       if (node->effect->effect_type_id() == "GammaCompressionEffect") {
+                               assert(node->incoming_links.size() == 1);
+                               assert(node->incoming_links[0]->output_alpha_type == ALPHA_PREMULTIPLIED);
+                               desired_type = ALPHA_POSTMULTIPLIED;
+                       }
+
+                       // Go through each input that is not premultiplied alpha, and insert
+                       // a conversion before it.
+                       for (unsigned j = 0; j < node->incoming_links.size(); ++j) {
+                               Node *input = node->incoming_links[j];
+                               assert(input->output_alpha_type != ALPHA_INVALID);
+                               if (input->output_alpha_type == desired_type ||
+                                   input->output_alpha_type == ALPHA_BLANK) {
+                                       continue;
+                               }
+                               Node *conversion;
+                               if (desired_type == ALPHA_PREMULTIPLIED) {
+                                       conversion = add_node(new AlphaMultiplicationEffect());
+                               } else {
+                                       conversion = add_node(new AlphaDivisionEffect());
+                               }
+                               conversion->output_alpha_type = desired_type;
+                               replace_sender(input, conversion);
+                               connect_nodes(input, conversion);
+                       }
+
+                       // Re-sort topologically, and propagate the new information.
+                       propagate_gamma_and_color_space();
+                       propagate_alpha();
+                       
+                       found_any = true;
+                       break;
+               }
+       
+               char filename[256];
+               sprintf(filename, "step%u-alphafix-iter%u.dot", step, ++alpha_propagation_pass);
+               output_dot(filename);
+               assert(alpha_propagation_pass < 100);
+       } while (found_any);
+
+       for (unsigned i = 0; i < nodes.size(); ++i) {
+               Node *node = nodes[i];
+               if (node->disabled) {
+                       continue;
+               }
+               assert(node->output_alpha_type != ALPHA_INVALID);
+       }
+}
+
+// Make so that the output is in the desired color space.
+void EffectChain::fix_output_color_space()
+{
+       Node *output = find_output_node();
+       if (output->output_color_space != output_format.color_space) {
+               Node *conversion = add_node(new ColorspaceConversionEffect());
+               CHECK(conversion->effect->set_int("source_space", output->output_color_space));
+               CHECK(conversion->effect->set_int("destination_space", output_format.color_space));
+               conversion->output_color_space = output_format.color_space;
+               connect_nodes(output, conversion);
+               propagate_alpha();
+               propagate_gamma_and_color_space();
+       }
+}
+
+// Make so that the output is in the desired pre-/postmultiplication alpha state.
+void EffectChain::fix_output_alpha()
+{
+       Node *output = find_output_node();
+       assert(output->output_alpha_type != ALPHA_INVALID);
+       if (output->output_alpha_type == ALPHA_BLANK) {
+               // No alpha output, so we don't care.
                return;
        }
+       if (output->output_alpha_type == ALPHA_PREMULTIPLIED &&
+           output_alpha_format == OUTPUT_ALPHA_FORMAT_POSTMULTIPLIED) {
+               Node *conversion = add_node(new AlphaDivisionEffect());
+               connect_nodes(output, conversion);
+               propagate_alpha();
+               propagate_gamma_and_color_space();
+       }
+       if (output->output_alpha_type == ALPHA_POSTMULTIPLIED &&
+           output_alpha_format == OUTPUT_ALPHA_FORMAT_PREMULTIPLIED) {
+               Node *conversion = add_node(new AlphaMultiplicationEffect());
+               connect_nodes(output, conversion);
+               propagate_alpha();
+               propagate_gamma_and_color_space();
+       }
+}
+
+bool EffectChain::node_needs_gamma_fix(Node *node)
+{
+       if (node->disabled) {
+               return false;
+       }
+
+       // Small hack since the output is not an explicit node:
+       // If we are the last node and our output is in the wrong
+       // space compared to EffectChain's output, we need to fix it.
+       // This will only take us to linear, but fix_output_gamma()
+       // will come and take us to the desired output gamma
+       // if it is needed.
+       //
+       // This needs to be before everything else, since it could
+       // even apply to inputs (if they are the only effect).
+       if (node->outgoing_links.empty() &&
+           node->output_gamma_curve != output_format.gamma_curve &&
+           node->output_gamma_curve != GAMMA_LINEAR) {
+               return true;
+       }
+
+       if (node->effect->num_inputs() == 0) {
+               return false;
+       }
+
+       // propagate_gamma_and_color_space() has already set our output
+       // to GAMMA_INVALID if the inputs differ, so we can rely on that,
+       // except for GammaCompressionEffect.
+       if (node->output_gamma_curve == GAMMA_INVALID) {
+               return true;
+       }
+       if (node->effect->effect_type_id() == "GammaCompressionEffect") {
+               assert(node->incoming_links.size() == 1);
+               return node->incoming_links[0]->output_gamma_curve != GAMMA_LINEAR;
+       }
+
+       return (node->effect->needs_linear_light() && node->output_gamma_curve != GAMMA_LINEAR);
+}
+
+// Very similar to fix_internal_color_spaces(), but for gamma.
+// There is one difference, though; before we start adding conversion nodes,
+// we see if we can get anything out of asking the sources to deliver
+// linear gamma directly. fix_internal_gamma_by_asking_inputs()
+// does that part, while fix_internal_gamma_by_inserting_nodes()
+// inserts nodes as needed afterwards.
+void EffectChain::fix_internal_gamma_by_asking_inputs(unsigned step)
+{
+       unsigned gamma_propagation_pass = 0;
+       bool found_any;
+       do {
+               found_any = false;
+               for (unsigned i = 0; i < nodes.size(); ++i) {
+                       Node *node = nodes[i];
+                       if (!node_needs_gamma_fix(node)) {
+                               continue;
+                       }
+
+                       // See if all inputs can give us linear gamma. If not, leave it.
+                       vector<Node *> nonlinear_inputs;
+                       find_all_nonlinear_inputs(node, &nonlinear_inputs);
+                       assert(!nonlinear_inputs.empty());
+
+                       bool all_ok = true;
+                       for (unsigned i = 0; i < nonlinear_inputs.size(); ++i) {
+                               Input *input = static_cast<Input *>(nonlinear_inputs[i]->effect);
+                               all_ok &= input->can_output_linear_gamma();
+                       }
+
+                       if (!all_ok) {
+                               continue;
+                       }
+
+                       for (unsigned i = 0; i < nonlinear_inputs.size(); ++i) {
+                               CHECK(nonlinear_inputs[i]->effect->set_int("output_linear_gamma", 1));
+                               nonlinear_inputs[i]->output_gamma_curve = GAMMA_LINEAR;
+                       }
+
+                       // Re-sort topologically, and propagate the new information.
+                       propagate_gamma_and_color_space();
+                       
+                       found_any = true;
+                       break;
+               }
+       
+               char filename[256];
+               sprintf(filename, "step%u-gammafix-iter%u.dot", step, ++gamma_propagation_pass);
+               output_dot(filename);
+               assert(gamma_propagation_pass < 100);
+       } while (found_any);
+}
+
+void EffectChain::fix_internal_gamma_by_inserting_nodes(unsigned step)
+{
+       unsigned gamma_propagation_pass = 0;
+       bool found_any;
+       do {
+               found_any = false;
+               for (unsigned i = 0; i < nodes.size(); ++i) {
+                       Node *node = nodes[i];
+                       if (!node_needs_gamma_fix(node)) {
+                               continue;
+                       }
 
-       // If not, look at the input phases, if any. We select the largest one
-       // (really assuming they all have the same aspect currently), by pixel count.
-       if (!phase->inputs.empty()) {
-               unsigned best_width = 0, best_height = 0;
-               for (unsigned i = 0; i < phase->inputs.size(); ++i) {
-                       Node *input = phase->inputs[i];
-                       assert(input->phase->output_width != 0);
-                       assert(input->phase->output_height != 0);
-                       if (input->phase->output_width * input->phase->output_height > best_width * best_height) {
-                               best_width = input->phase->output_width;
-                               best_height = input->phase->output_height;
+                       // Special case: We could be an input and still be asked to
+                       // fix our gamma; if so, we should be the only node
+                       // (as node_needs_gamma_fix() would only return true in
+                       // for an input in that case). That means we should insert
+                       // a conversion node _after_ ourselves.
+                       if (node->incoming_links.empty()) {
+                               assert(node->outgoing_links.empty());
+                               Node *conversion = add_node(new GammaExpansionEffect());
+                               CHECK(conversion->effect->set_int("source_curve", node->output_gamma_curve));
+                               conversion->output_gamma_curve = GAMMA_LINEAR;
+                               connect_nodes(node, conversion);
                        }
+
+                       // If not, go through each input that is not linear gamma,
+                       // and insert a gamma conversion after it.
+                       for (unsigned j = 0; j < node->incoming_links.size(); ++j) {
+                               Node *input = node->incoming_links[j];
+                               assert(input->output_gamma_curve != GAMMA_INVALID);
+                               if (input->output_gamma_curve == GAMMA_LINEAR) {
+                                       continue;
+                               }
+                               Node *conversion = add_node(new GammaExpansionEffect());
+                               CHECK(conversion->effect->set_int("source_curve", input->output_gamma_curve));
+                               conversion->output_gamma_curve = GAMMA_LINEAR;
+                               replace_sender(input, conversion);
+                               connect_nodes(input, conversion);
+                       }
+
+                       // Re-sort topologically, and propagate the new information.
+                       propagate_alpha();
+                       propagate_gamma_and_color_space();
+                       
+                       found_any = true;
+                       break;
                }
-               assert(best_width != 0);
-               assert(best_height != 0);
-               phase->output_width = best_width;
-               phase->output_height = best_height;
+       
+               char filename[256];
+               sprintf(filename, "step%u-gammafix-iter%u.dot", step, ++gamma_propagation_pass);
+               output_dot(filename);
+               assert(gamma_propagation_pass < 100);
+       } while (found_any);
+
+       for (unsigned i = 0; i < nodes.size(); ++i) {
+               Node *node = nodes[i];
+               if (node->disabled) {
+                       continue;
+               }
+               assert(node->output_gamma_curve != GAMMA_INVALID);
+       }
+}
+
+// Make so that the output is in the desired gamma.
+// Note that this assumes linear input gamma, so it might create the need
+// for another pass of fix_internal_gamma().
+void EffectChain::fix_output_gamma()
+{
+       Node *output = find_output_node();
+       if (output->output_gamma_curve != output_format.gamma_curve) {
+               Node *conversion = add_node(new GammaCompressionEffect());
+               CHECK(conversion->effect->set_int("destination_curve", output_format.gamma_curve));
+               conversion->output_gamma_curve = output_format.gamma_curve;
+               connect_nodes(output, conversion);
+       }
+}
+       
+// If the user has requested dither, add a DitherEffect right at the end
+// (after GammaCompressionEffect etc.). This needs to be done after everything else,
+// since dither is about the only effect that can _not_ be done in linear space.
+void EffectChain::add_dither_if_needed()
+{
+       if (num_dither_bits == 0) {
                return;
        }
+       Node *output = find_output_node();
+       Node *dither = add_node(new DitherEffect());
+       CHECK(dither->effect->set_int("num_bits", num_dither_bits));
+       connect_nodes(output, dither);
 
-       // OK, no inputs. Just use the global width/height.
-       // TODO: We probably want to use the texture's size eventually.
-       phase->output_width = width;
-       phase->output_height = height;
+       dither_effect = dither->effect;
 }
 
-void EffectChain::finalize()
+// Find the output node. This is, simply, one that has no outgoing links.
+// If there are multiple ones, the graph is malformed (we do not support
+// multiple outputs right now).
+Node *EffectChain::find_output_node()
 {
-       output_dot("final.dot");
-
-       // Find the output effect. This is, simply, one that has no outgoing links.
-       // If there are multiple ones, the graph is malformed (we do not support
-       // multiple outputs right now).
-       std::vector<Node *> output_nodes;
+       vector<Node *> output_nodes;
        for (unsigned i = 0; i < nodes.size(); ++i) {
                Node *node = nodes[i];
+               if (node->disabled) {
+                       continue;
+               }
                if (node->outgoing_links.empty()) {
                        output_nodes.push_back(node);
                }
        }
        assert(output_nodes.size() == 1);
-       Node *output_node = output_nodes[0];
+       return output_nodes[0];
+}
 
-       // Add normalizers to get the output format right.
-       if (output_node->output_color_space != output_format.color_space) {
-               ColorSpaceConversionEffect *colorspace_conversion = new ColorSpaceConversionEffect();
-               colorspace_conversion->set_int("source_space", output_node->output_color_space);
-               colorspace_conversion->set_int("destination_space", output_format.color_space);
-               std::vector<Effect *> inputs;
-               inputs.push_back(output_node->effect);
-               colorspace_conversion->add_self_to_effect_chain(this, inputs);
+void EffectChain::finalize()
+{
+       // Save the current locale, and set it to C, so that we can output decimal
+       // numbers with printf and be sure to get them in the format mandated by GLSL.
+       char *saved_locale = setlocale(LC_NUMERIC, "C");
 
-               assert(node_map.count(colorspace_conversion) != 0);
-               output_node = node_map[colorspace_conversion];
-               output_node->output_color_space = output_format.color_space;
-       }
-       if (output_node->output_gamma_curve != output_format.gamma_curve) {
-               if (output_node->output_gamma_curve != GAMMA_LINEAR) {
-                       output_node = normalize_to_linear_gamma(output_node);
-               }
-               GammaCompressionEffect *gamma_conversion = new GammaCompressionEffect();
-               gamma_conversion->set_int("destination_curve", output_format.gamma_curve);
-               std::vector<Effect *> inputs;
-               inputs.push_back(output_node->effect);
-               gamma_conversion->add_self_to_effect_chain(this, inputs);
+       // Output the graph as it is before we do any conversions on it.
+       output_dot("step0-start.dot");
 
-               assert(node_map.count(gamma_conversion) != 0);
-               output_node = node_map[gamma_conversion];
-               output_node->output_gamma_curve = output_format.gamma_curve;
+       // Give each effect in turn a chance to rewrite its own part of the graph.
+       // Note that if more effects are added as part of this, they will be
+       // picked up as part of the same for loop, since they are added at the end.
+       for (unsigned i = 0; i < nodes.size(); ++i) {
+               nodes[i]->effect->rewrite_graph(this, nodes[i]);
        }
-
+       output_dot("step1-rewritten.dot");
+
+       find_color_spaces_for_inputs();
+       output_dot("step2-input-colorspace.dot");
+
+       propagate_alpha();
+       output_dot("step3-propagated-alpha.dot");
+
+       propagate_gamma_and_color_space();
+       output_dot("step4-propagated-all.dot");
+
+       fix_internal_color_spaces();
+       fix_internal_alpha(6);
+       fix_output_color_space();
+       output_dot("step7-output-colorspacefix.dot");
+       fix_output_alpha();
+       output_dot("step8-output-alphafix.dot");
+
+       // Note that we need to fix gamma after colorspace conversion,
+       // because colorspace conversions might create needs for gamma conversions.
+       // Also, we need to run an extra pass of fix_internal_gamma() after 
+       // fixing the output gamma, as we only have conversions to/from linear,
+       // and fix_internal_alpha() since GammaCompressionEffect needs
+       // postmultiplied input.
+       fix_internal_gamma_by_asking_inputs(9);
+       fix_internal_gamma_by_inserting_nodes(10);
+       fix_output_gamma();
+       output_dot("step11-output-gammafix.dot");
+       propagate_alpha();
+       output_dot("step12-output-alpha-propagated.dot");
+       fix_internal_alpha(13);
+       output_dot("step14-output-alpha-fixed.dot");
+       fix_internal_gamma_by_asking_inputs(15);
+       fix_internal_gamma_by_inserting_nodes(16);
+
+       output_dot("step17-before-dither.dot");
+
+       add_dither_if_needed();
+
+       output_dot("step18-final.dot");
+       
        // Construct all needed GLSL programs, starting at the output.
-       construct_glsl_programs(output_node);
+       construct_glsl_programs(find_output_node());
 
-       // If we have more than one phase, we need intermediate render-to-texture.
-       // Construct an FBO, and then as many textures as we need.
-       // We choose the simplest option of having one texture per output,
-       // since otherwise this turns into an (albeit simple)
-       // register allocation problem.
-       if (phases.size() > 1) {
-               glGenFramebuffers(1, &fbo);
-
-               for (unsigned i = 0; i < phases.size() - 1; ++i) {
-                       find_output_size(phases[i]);
+       output_dot("step19-split-to-phases.dot");
 
-                       Node *output_node = phases[i]->effects.back();
-                       glGenTextures(1, &output_node->output_texture);
-                       check_error();
-                       glBindTexture(GL_TEXTURE_2D, output_node->output_texture);
-                       check_error();
-                       glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
-                       check_error();
-                       glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
-                       check_error();
-                       glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA16F_ARB, phases[i]->output_width, phases[i]->output_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
-                       check_error();
-
-                       output_node->output_texture_width = phases[i]->output_width;
-                       output_node->output_texture_height = phases[i]->output_height;
-               }
-       }
-               
        for (unsigned i = 0; i < inputs.size(); ++i) {
                inputs[i]->finalize();
        }
@@ -593,12 +1419,26 @@ void EffectChain::finalize()
        assert(phases[0]->inputs.empty());
        
        finalized = true;
+       setlocale(LC_NUMERIC, saved_locale);
 }
 
-void EffectChain::render_to_screen()
+void EffectChain::render_to_fbo(GLuint dest_fbo, unsigned width, unsigned height)
 {
        assert(finalized);
 
+       // Save original viewport.
+       GLuint x = 0, y = 0;
+       GLuint fbo = 0;
+
+       if (width == 0 && height == 0) {
+               GLint viewport[4];
+               glGetIntegerv(GL_VIEWPORT, viewport);
+               x = viewport[0];
+               y = viewport[1];
+               width = viewport[2];
+               height = viewport[3];
+       }
+
        // Basic state.
        glDisable(GL_BLEND);
        check_error();
@@ -615,34 +1455,26 @@ void EffectChain::render_to_screen()
        glLoadIdentity();
 
        if (phases.size() > 1) {
+               glGenFramebuffers(1, &fbo);
+               check_error();
                glBindFramebuffer(GL_FRAMEBUFFER, fbo);
                check_error();
        }
 
-       std::set<Node *> generated_mipmaps;
+       set<Node *> generated_mipmaps;
+
+       // We choose the simplest option of having one texture per output,
+       // since otherwise this turns into an (albeit simple) register allocation problem.
+       map<Phase *, GLuint> output_textures;
 
        for (unsigned phase = 0; phase < phases.size(); ++phase) {
-               // See if the requested output size has changed. If so, we need to recreate
-               // the texture (and before we start setting up inputs).
+               // Find a texture for this phase.
+               inform_input_sizes(phases[phase]);
                if (phase != phases.size() - 1) {
                        find_output_size(phases[phase]);
 
-                       Node *output_node = phases[phase]->effects.back();
-
-                       if (output_node->output_texture_width != phases[phase]->output_width ||
-                           output_node->output_texture_height != phases[phase]->output_height) {
-                               glActiveTexture(GL_TEXTURE0);
-                               check_error();
-                               glBindTexture(GL_TEXTURE_2D, output_node->output_texture);
-                               check_error();
-                               glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA16F_ARB, phases[phase]->output_width, phases[phase]->output_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
-                               check_error();
-                               glBindTexture(GL_TEXTURE_2D, 0);
-                               check_error();
-
-                               output_node->output_texture_width = phases[phase]->output_width;
-                               output_node->output_texture_height = phases[phase]->output_height;
-                       }
+                       GLuint tex_num = resource_pool->create_2d_texture(GL_RGBA16F_ARB, phases[phase]->output_width, phases[phase]->output_height);
+                       output_textures.insert(make_pair(phases[phase], tex_num));
                }
 
                glUseProgram(phases[phase]->glsl_program_num);
@@ -652,7 +1484,7 @@ void EffectChain::render_to_screen()
                for (unsigned sampler = 0; sampler < phases[phase]->inputs.size(); ++sampler) {
                        glActiveTexture(GL_TEXTURE0 + sampler);
                        Node *input = phases[phase]->inputs[sampler];
-                       glBindTexture(GL_TEXTURE_2D, input->output_texture);
+                       glBindTexture(GL_TEXTURE_2D, output_textures[input->phase]);
                        check_error();
                        if (phases[phase]->input_needs_mipmaps) {
                                if (generated_mipmaps.count(input) == 0) {
@@ -666,27 +1498,38 @@ void EffectChain::render_to_screen()
                                glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
                                check_error();
                        }
+                       glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+                       check_error();
+                       glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+                       check_error();
 
-                       std::string texture_name = std::string("tex_") + input->effect_id;
+                       string texture_name = string("tex_") + phases[phase]->effect_ids[input];
                        glUniform1i(glGetUniformLocation(phases[phase]->glsl_program_num, texture_name.c_str()), sampler);
                        check_error();
                }
 
                // And now the output.
                if (phase == phases.size() - 1) {
-                       // Last phase goes directly to the screen.
-                       glBindFramebuffer(GL_FRAMEBUFFER, 0);
+                       // Last phase goes to the output the user specified.
+                       glBindFramebuffer(GL_FRAMEBUFFER, dest_fbo);
                        check_error();
-                       glViewport(0, 0, width, height);
+                       GLenum status = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT);
+                       assert(status == GL_FRAMEBUFFER_COMPLETE);
+                       glViewport(x, y, width, height);
+                       if (dither_effect != NULL) {
+                               CHECK(dither_effect->set_int("output_width", width));
+                               CHECK(dither_effect->set_int("output_height", height));
+                       }
                } else {
-                       Node *output_node = phases[phase]->effects.back();
                        glFramebufferTexture2D(
                                GL_FRAMEBUFFER,
                                GL_COLOR_ATTACHMENT0,
                                GL_TEXTURE_2D,
-                               output_node->output_texture,
+                               output_textures[phases[phase]],
                                0);
                        check_error();
+                       GLenum status = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT);
+                       assert(status == GL_FRAMEBUFFER_COMPLETE);
                        glViewport(0, 0, phases[phase]->output_width, phases[phase]->output_height);
                }
 
@@ -694,7 +1537,7 @@ void EffectChain::render_to_screen()
                unsigned sampler_num = phases[phase]->inputs.size();
                for (unsigned i = 0; i < phases[phase]->effects.size(); ++i) {
                        Node *node = phases[phase]->effects[i];
-                       node->effect->set_gl_state(phases[phase]->glsl_program_num, node->effect_id, &sampler_num);
+                       node->effect->set_gl_state(phases[phase]->glsl_program_num, phases[phase]->effect_ids[node], &sampler_num);
                        check_error();
                }
 
@@ -721,4 +1564,18 @@ void EffectChain::render_to_screen()
                        node->effect->clear_gl_state();
                }
        }
+
+       for (map<Phase *, GLuint>::const_iterator texture_it = output_textures.begin();
+            texture_it != output_textures.end();
+            ++texture_it) {
+               resource_pool->release_2d_texture(texture_it->second);
+       }
+
+       glBindFramebuffer(GL_FRAMEBUFFER, 0);
+       check_error();
+
+       if (fbo != 0) {
+               glDeleteFramebuffers(1, &fbo);
+               check_error();
+       }
 }