[movit] / effect_chain.cpp

#define GL_GLEXT_PROTOTYPES 1

#include <stdio.h>
#include <string.h>
#include <assert.h>

#include <algorithm>
#include <set>
#include <stack>
#include <vector>

#include "util.h"
#include "effect_chain.h"
#include "gamma_expansion_effect.h"
#include "gamma_compression_effect.h"
#include "colorspace_conversion_effect.h"
#include "input.h"
#include "opengl.h"

EffectChain::EffectChain(unsigned width, unsigned height)
        : width(width),
          height(height),
          finalized(false) {}

Input *EffectChain::add_input(Input *input)
{
        char eff_id[256];
        sprintf(eff_id, "src_image%u", (unsigned)inputs.size());

        effects.push_back(input);
        inputs.push_back(input);
        output_color_space.insert(std::make_pair(input, input->get_color_space()));
        output_gamma_curve.insert(std::make_pair(input, input->get_gamma_curve()));
        effect_ids.insert(std::make_pair(input, eff_id));
        incoming_links.insert(std::make_pair(input, std::vector<Effect *>()));
        return input;
}

void EffectChain::add_output(const ImageFormat &format)
{
        output_format = format;
}

void EffectChain::add_effect_raw(Effect *effect, const std::vector<Effect *> &inputs)
{
        char effect_id[256];
        sprintf(effect_id, "eff%u", (unsigned)effects.size());

        effects.push_back(effect);
        effect_ids.insert(std::make_pair(effect, effect_id));
        assert(inputs.size() == effect->num_inputs());
        for (unsigned i = 0; i < inputs.size(); ++i) {
                assert(std::find(effects.begin(), effects.end(), inputs[i]) != effects.end());
                outgoing_links[inputs[i]].push_back(effect);
        }
        incoming_links.insert(std::make_pair(effect, inputs));
        output_gamma_curve[effect] = output_gamma_curve[last_added_effect()];
        output_color_space[effect] = output_color_space[last_added_effect()];
}

void EffectChain::find_all_nonlinear_inputs(Effect *effect,
                                            std::vector<Input *> *nonlinear_inputs,
                                            std::vector<Effect *> *intermediates)
{
        assert(output_gamma_curve.count(effect) != 0);
        if (output_gamma_curve[effect] == GAMMA_LINEAR) {
                return;
        }
        if (effect->num_inputs() == 0) {
                nonlinear_inputs->push_back(static_cast<Input *>(effect));
        } else {
                intermediates->push_back(effect);

                assert(incoming_links.count(effect) == 1);
                std::vector<Effect *> deps = incoming_links[effect];
                assert(effect->num_inputs() == deps.size());
                for (unsigned i = 0; i < deps.size(); ++i) {
                        find_all_nonlinear_inputs(deps[i], nonlinear_inputs, intermediates);
                }
        }
}

Effect *EffectChain::normalize_to_linear_gamma(Effect *input)
{
        // 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<Input *> nonlinear_inputs;
        std::vector<Effect *> intermediates;
        find_all_nonlinear_inputs(input, &nonlinear_inputs, &intermediates);

        bool all_ok = true;
        for (unsigned i = 0; i < nonlinear_inputs.size(); ++i) {
                all_ok &= nonlinear_inputs[i]->can_output_linear_gamma();
        }

        if (all_ok) {
                for (unsigned i = 0; i < nonlinear_inputs.size(); ++i) {
                        bool ok = nonlinear_inputs[i]->set_int("output_linear_gamma", 1);
                        assert(ok);
                        output_gamma_curve[nonlinear_inputs[i]] = GAMMA_LINEAR;
                }
                for (unsigned i = 0; i < intermediates.size(); ++i) {
                        output_gamma_curve[intermediates[i]] = GAMMA_LINEAR;
                }
                return input;
        }

        // OK, that didn't work. Insert a conversion effect.
        GammaExpansionEffect *gamma_conversion = new GammaExpansionEffect();
        gamma_conversion->set_int("source_curve", output_gamma_curve[input]);
        std::vector<Effect *> inputs;
        inputs.push_back(input);
        gamma_conversion->add_self_to_effect_chain(this, inputs);
        output_gamma_curve[gamma_conversion] = GAMMA_LINEAR;
        return gamma_conversion;
}

Effect *EffectChain::normalize_to_srgb(Effect *input)
{
        assert(output_gamma_curve.count(input) != 0);
        assert(output_color_space.count(input) != 0);
        assert(output_gamma_curve[input] == GAMMA_LINEAR);
        ColorSpaceConversionEffect *colorspace_conversion = new ColorSpaceConversionEffect();
        colorspace_conversion->set_int("source_space", output_color_space[input]);
        colorspace_conversion->set_int("destination_space", COLORSPACE_sRGB);
        std::vector<Effect *> inputs;
        inputs.push_back(input);
        colorspace_conversion->add_self_to_effect_chain(this, inputs);
        output_color_space[colorspace_conversion] = COLORSPACE_sRGB;
        return colorspace_conversion;
}

Effect *EffectChain::add_effect(Effect *effect, const std::vector<Effect *> &inputs)
{
        assert(inputs.size() == effect->num_inputs());

        std::vector<Effect *> normalized_inputs = inputs;
        for (unsigned i = 0; i < normalized_inputs.size(); ++i) {
                assert(output_gamma_curve.count(normalized_inputs[i]) != 0);
                if (effect->needs_linear_light() && output_gamma_curve[normalized_inputs[i]] != GAMMA_LINEAR) {
                        normalized_inputs[i] = normalize_to_linear_gamma(normalized_inputs[i]);
                }
                assert(output_color_space.count(normalized_inputs[i]) != 0);
                if (effect->needs_srgb_primaries() && output_color_space[normalized_inputs[i]] != COLORSPACE_sRGB) {
                        normalized_inputs[i] = normalize_to_srgb(normalized_inputs[i]);
                }
        }

        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)
{
        std::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));
                        break;
                }

                output.append(text.substr(start, pos - start));
                output.append(prefix);
                output.append("_");

                pos += strlen("PREFIX(");
        
                // Output stuff until we find the matching ), which we then eat.
                int depth = 1;
                size_t end_arg_pos = pos;
                while (end_arg_pos < text.size()) {
                        if (text[end_arg_pos] == '(') {
                                ++depth;
                        } else if (text[end_arg_pos] == ')') {
                                --depth;
                                if (depth == 0) {
                                        break;
                                }
                        }
                        ++end_arg_pos;
                }
                output.append(text.substr(pos, end_arg_pos - pos));
                ++end_arg_pos;
                assert(depth == 0);
                start = end_arg_pos;
        }
        return output;
}

EffectChain::Phase *EffectChain::compile_glsl_program(const std::vector<Effect *> &inputs, const std::vector<Effect *> &effects)
{
        assert(!effects.empty());

        // Deduplicate the inputs.
        std::vector<Effect *> 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());

        bool input_needs_mipmaps = false;
        std::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) {
                Effect *effect = true_inputs[i];
                assert(effect_ids.count(effect) != 0);
                std::string effect_id = effect_ids[effect];
        
                frag_shader += std::string("uniform sampler2D tex_") + effect_id + ";\n";       
                frag_shader += std::string("vec4 ") + effect_id + "(vec2 tc) {\n";
                if (effect->num_inputs() == 0) {
                        // OpenGL's origin is bottom-left, but most graphics software assumes
                        // a top-left origin. Thus, for inputs that come from the user,
                        // we flip the y coordinate. However, for FBOs, the origin
                        // is all correct, so don't do anything.
                        frag_shader += "\ttc.y = 1.0f - tc.y;\n";
                }
                frag_shader += "\treturn texture2D(tex_" + effect_id + ", tc);\n";
                frag_shader += "}\n";
                frag_shader += "\n";
        }

        std::string last_effect_id;
        for (unsigned i = 0; i < effects.size(); ++i) {
                Effect *effect = effects[i];
                assert(effect != NULL);
                assert(effect_ids.count(effect) != 0);
                std::string effect_id = effect_ids[effect];
                last_effect_id = effect_id;

                if (incoming_links[effect].size() == 1) {
                        frag_shader += std::string("#define INPUT ") + effect_ids[incoming_links[effect][0]] + "\n";
                } else {
                        for (unsigned j = 0; j < incoming_links[effect].size(); ++j) {
                                char buf[256];
                                sprintf(buf, "#define INPUT%d %s\n", j + 1, effect_ids[incoming_links[effect][j]].c_str());
                                frag_shader += buf;
                        }
                }
        
                frag_shader += "\n";
                frag_shader += std::string("#define FUNCNAME ") + effect_id + "\n";
                frag_shader += replace_prefix(effect->output_convenience_uniforms(), effect_id);
                frag_shader += replace_prefix(effect->output_fragment_shader(), effect_id);
                frag_shader += "#undef PREFIX\n";
                frag_shader += "#undef FUNCNAME\n";
                if (incoming_links[effect].size() == 1) {
                        frag_shader += "#undef INPUT\n";
                } else {
                        for (unsigned j = 0; j < incoming_links[effect].size(); ++j) {
                                char buf[256];
                                sprintf(buf, "#undef INPUT%d\n", j + 1);
                                frag_shader += buf;
                        }
                }
                frag_shader += "\n";

                input_needs_mipmaps |= effect->needs_mipmaps();
        }
        for (unsigned i = 0; i < effects.size(); ++i) {
                Effect *effect = effects[i];
                if (effect->num_inputs() == 0) {
                        effect->set_int("needs_mipmaps", input_needs_mipmaps);
                }
        }
        assert(!last_effect_id.empty());
        frag_shader += std::string("#define INPUT ") + last_effect_id + "\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->input_needs_mipmaps = input_needs_mipmaps;
        phase->inputs = true_inputs;
        phase->effects = effects;

        return phase;
}

// Construct GLSL programs, starting at the given effect and following
// the chain from there. We end a program every time we come to an effect
// marked as "needs texture bounce", one that is used by multiple other
// effects, every time an effect wants to change the output size,
// and of course at the end.
//
// We follow a quite simple depth-first search from the output, although
// without any explicit recursion.
void EffectChain::construct_glsl_programs(Effect *output)
{
        // Which effects have already been completed in this phase?
        // We need to keep track of it, as an effect with multiple outputs
        // could otherwise be calculate multiple times.
        std::set<Effect *> 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<Effect *> this_phase_inputs;
        std::vector<Effect *> this_phase_effects;

        // Effects that we have yet to calculate, but that we know should
        // be in the current phase.
        std::stack<Effect *> 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<Effect *> effects_todo_other_phases;

        effects_todo_this_phase.push(output);

        for ( ;; ) {  // Termination condition within loop.
                if (!effects_todo_this_phase.empty()) {
                        // OK, we have more to do this phase.
                        Effect *effect = 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(effect) == 0);

                        this_phase_effects.push_back(effect);
                        completed_effects.insert(effect);

                        // Find all the dependencies of this effect, and add them to the stack.
                        assert(incoming_links.count(effect) == 1);
                        std::vector<Effect *> deps = incoming_links[effect];
                        assert(effect->num_inputs() == deps.size());
                        for (unsigned i = 0; i < deps.size(); ++i) {
                                bool start_new_phase = false;

                                if (effect->needs_texture_bounce()) {
                                        start_new_phase = true;
                                }

                                assert(outgoing_links.count(deps[i]) == 1);
                                if (outgoing_links[deps[i]].size() > 1 && deps[i]->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]->changes_output_size()) {
                                        start_new_phase = true;
                                }

                                if (start_new_phase) {
                                        effects_todo_other_phases.push(deps[i]);
                                        this_phase_inputs.push_back(deps[i]);
                                } else {
                                        effects_todo_this_phase.push(deps[i]);
                                }
                        }
                        continue;
                }

                // No more effects to do this phase. Take all the ones we have,
                // and create a GLSL program for it.
                if (!this_phase_effects.empty()) {
                        reverse(this_phase_effects.begin(), this_phase_effects.end());
                        phases.push_back(compile_glsl_program(this_phase_inputs, this_phase_effects));
                        output_effects_to_phase.insert(std::make_pair(this_phase_effects.back(), phases.back()));
                        this_phase_inputs.clear();
                        this_phase_effects.clear();
                }
                assert(this_phase_inputs.empty());
                assert(this_phase_effects.empty());

                // If we have no effects left, exit.
                if (effects_todo_other_phases.empty()) {
                        break;
                }

                Effect *effect = effects_todo_other_phases.top();
                effects_todo_other_phases.pop();

                if (completed_effects.count(effect) == 0) {
                        // Start a new phase, calculating from this effect.
                        effects_todo_this_phase.push(effect);
                }
        }

        // 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());
}

void EffectChain::find_output_size(EffectChain::Phase *phase)
{
        Effect *output_effect = phase->effects.back();

        // If the last effect explicitly sets an output size,
        // use that.
        if (output_effect->changes_output_size()) {
                output_effect->get_output_size(&phase->output_width, &phase->output_height);
                return;
        }

        // 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) {
                        Effect *input = phase->inputs[i];
                        assert(output_effects_to_phase.count(input) != 0);
                        const Phase *input_phase = output_effects_to_phase[input];
                        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;
                        }
                }
                assert(best_width != 0);
                assert(best_height != 0);
                phase->output_width = best_width;
                phase->output_height = best_height;
                return;
        }

        // 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;
}

void EffectChain::finalize()
{
        // 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<Effect *> output_effects;
        for (unsigned i = 0; i < effects.size(); ++i) {
                Effect *effect = effects[i];
                if (outgoing_links.count(effect) == 0 || outgoing_links[effect].size() == 0) {
                        output_effects.push_back(effect);
                }
        }
        assert(output_effects.size() == 1);
        Effect *output_effect = output_effects[0];

        // Add normalizers to get the output format right.
        assert(output_gamma_curve.count(output_effect) != 0);
        assert(output_color_space.count(output_effect) != 0);
        ColorSpace current_color_space = output_color_space[output_effect];
        if (current_color_space != output_format.color_space) {
                ColorSpaceConversionEffect *colorspace_conversion = new ColorSpaceConversionEffect();
                colorspace_conversion->set_int("source_space", current_color_space);
                colorspace_conversion->set_int("destination_space", output_format.color_space);
                std::vector<Effect *> inputs;
                inputs.push_back(output_effect);
                colorspace_conversion->add_self_to_effect_chain(this, inputs);
                output_color_space[colorspace_conversion] = output_format.color_space;
                output_effect = colorspace_conversion;
        }
        GammaCurve current_gamma_curve = output_gamma_curve[output_effect];
        if (current_gamma_curve != output_format.gamma_curve) {
                if (current_gamma_curve != GAMMA_LINEAR) {
                        output_effect = normalize_to_linear_gamma(output_effect);
                        current_gamma_curve = GAMMA_LINEAR;
                }
                GammaCompressionEffect *gamma_conversion = new GammaCompressionEffect();
                gamma_conversion->set_int("destination_curve", output_format.gamma_curve);
                std::vector<Effect *> inputs;
                inputs.push_back(output_effect);
                gamma_conversion->add_self_to_effect_chain(this, inputs);
                output_gamma_curve[gamma_conversion] = output_format.gamma_curve;
                output_effect = gamma_conversion;
        }

        // Construct all needed GLSL programs, starting at the output.
        construct_glsl_programs(output_effect);

        // 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]);

                        Effect *output_effect = phases[i]->effects.back();
                        GLuint temp_texture;
                        glGenTextures(1, &temp_texture);
                        check_error();
                        glBindTexture(GL_TEXTURE_2D, temp_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();
                        effect_output_textures.insert(std::make_pair(output_effect, temp_texture));
                        effect_output_texture_sizes.insert(std::make_pair(output_effect, std::make_pair(phases[i]->output_width, phases[i]->output_height)));
                }
        }
                
        for (unsigned i = 0; i < inputs.size(); ++i) {
                inputs[i]->finalize();
        }
        
        finalized = true;
}

void EffectChain::render_to_screen()
{
        assert(finalized);

        // Basic state.
        glDisable(GL_BLEND);
        check_error();
        glDisable(GL_DEPTH_TEST);
        check_error();
        glDepthMask(GL_FALSE);
        check_error();

        glMatrixMode(GL_PROJECTION);
        glLoadIdentity();
        glOrtho(0.0, 1.0, 0.0, 1.0, 0.0, 1.0);

        glMatrixMode(GL_MODELVIEW);
        glLoadIdentity();

        if (phases.size() > 1) {
                glBindFramebuffer(GL_FRAMEBUFFER, fbo);
                check_error();
        }

        std::set<Effect *> generated_mipmaps;
        for (unsigned i = 0; i < inputs.size(); ++i) {
                // Inputs generate their own mipmaps if they need to
                // (see input.cpp).
                generated_mipmaps.insert(inputs[i]);
        }

        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).
                if (phase != phases.size() - 1) {
                        find_output_size(phases[phase]);

                        Effect *output_effect = phases[phase]->effects.back();
                        assert(effect_output_texture_sizes.count(output_effect) != 0);
                        std::pair<GLuint, GLuint> old_size = effect_output_texture_sizes[output_effect];

                        if (old_size.first != phases[phase]->output_width ||
                            old_size.second != phases[phase]->output_height) {
                                glActiveTexture(GL_TEXTURE0);
                                check_error();
                                assert(effect_output_textures.count(output_effect) != 0);
                                glBindTexture(GL_TEXTURE_2D, effect_output_textures[output_effect]);
                                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();
                                effect_output_texture_sizes[output_effect] = std::make_pair(phases[phase]->output_width, phases[phase]->output_height);
                                glBindTexture(GL_TEXTURE_2D, 0);
                                check_error();
                        }
                }

                glUseProgram(phases[phase]->glsl_program_num);
                check_error();

                // Set up RTT inputs for this phase.
                for (unsigned sampler = 0; sampler < phases[phase]->inputs.size(); ++sampler) {
                        glActiveTexture(GL_TEXTURE0 + sampler);
                        Effect *input = phases[phase]->inputs[sampler];
                        assert(effect_output_textures.count(input) != 0);
                        glBindTexture(GL_TEXTURE_2D, effect_output_textures[input]);
                        check_error();
                        if (phases[phase]->input_needs_mipmaps) {
                                if (generated_mipmaps.count(input) == 0) {
                                        glGenerateMipmap(GL_TEXTURE_2D);
                                        check_error();
                                        generated_mipmaps.insert(input);
                                }
                                glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_NEAREST);
                                check_error();
                        } else {
                                glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
                                check_error();
                        }

                        assert(effect_ids.count(input));
                        std::string texture_name = std::string("tex_") + 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);
                        check_error();
                        glViewport(0, 0, width, height);
                } else {
                        Effect *output_effect = phases[phase]->effects.back();
                        assert(effect_output_textures.count(output_effect) != 0);
                        glFramebufferTexture2D(
                                GL_FRAMEBUFFER,
                                GL_COLOR_ATTACHMENT0,
                                GL_TEXTURE_2D,
                                effect_output_textures[output_effect],
                                0);
                        check_error();
                        glViewport(0, 0, phases[phase]->output_width, phases[phase]->output_height);
                }

                // Give the required parameters to all the effects.
                unsigned sampler_num = phases[phase]->inputs.size();
                for (unsigned i = 0; i < phases[phase]->effects.size(); ++i) {
                        Effect *effect = phases[phase]->effects[i];
                        effect->set_gl_state(phases[phase]->glsl_program_num, effect_ids[effect], &sampler_num);
                        check_error();
                }

                // Now draw!
                glBegin(GL_QUADS);

                glTexCoord2f(0.0f, 0.0f);
                glVertex2f(0.0f, 0.0f);

                glTexCoord2f(1.0f, 0.0f);
                glVertex2f(1.0f, 0.0f);

                glTexCoord2f(1.0f, 1.0f);
                glVertex2f(1.0f, 1.0f);

                glTexCoord2f(0.0f, 1.0f);
                glVertex2f(0.0f, 1.0f);

                glEnd();
                check_error();

                for (unsigned i = 0; i < phases[phase]->effects.size(); ++i) {
                        Effect *effect = phases[phase]->effects[i];
                        effect->clear_gl_state();
                }
        }
}