git.sesse.net Git - movit/blob - effect_chain.cpp

   1 #define GL_GLEXT_PROTOTYPES 1
   2
   3 #include <stdio.h>
   4 #include <string.h>
   5 #include <assert.h>
   6
   7 #include <algorithm>
   8 #include <set>
   9 #include <stack>
  10 #include <vector>
  11
  12 #include "util.h"
  13 #include "effect_chain.h"
  14 #include "gamma_expansion_effect.h"
  15 #include "gamma_compression_effect.h"
  16 #include "colorspace_conversion_effect.h"
  17 #include "input.h"
  18 #include "opengl.h"
  19
  20 EffectChain::EffectChain(unsigned width, unsigned height)
  21         : width(width),
  22           height(height),
  23           finalized(false) {}
  24
  25 Input *EffectChain::add_input(Input *input)
  26 {
  27         char eff_id[256];
  28         sprintf(eff_id, "src_image%u", (unsigned)inputs.size());
  29
  30         inputs.push_back(input);
  31
  32         Node *node = new Node;
  33         node->effect = input;
  34         node->effect_id = eff_id;
  35         node->output_color_space = input->get_color_space();
  36         node->output_gamma_curve = input->get_gamma_curve();
  37
  38         nodes.push_back(node);
  39         node_map[input] = node;
  40
  41         return input;
  42 }
  43
  44 void EffectChain::add_output(const ImageFormat &format)
  45 {
  46         output_format = format;
  47 }
  48
  49 void EffectChain::add_effect_raw(Effect *effect, const std::vector<Effect *> &inputs)
  50 {
  51         char effect_id[256];
  52         sprintf(effect_id, "eff%u", (unsigned)nodes.size());
  53
  54         Node *node = new Node;
  55         node->effect = effect;
  56         node->effect_id = effect_id;
  57
  58         assert(inputs.size() == effect->num_inputs());
  59         assert(inputs.size() >= 1);
  60         for (unsigned i = 0; i < inputs.size(); ++i) {
  61                 assert(node_map.count(inputs[i]) != 0);
  62                 node_map[inputs[i]]->outgoing_links.push_back(node);
  63                 node->incoming_links.push_back(node_map[inputs[i]]);
  64                 if (i == 0) {
  65                         node->output_gamma_curve = node_map[inputs[i]]->output_gamma_curve;
  66                         node->output_color_space = node_map[inputs[i]]->output_color_space;
  67                 } else {
  68                         assert(node->output_gamma_curve == node_map[inputs[i]]->output_gamma_curve);
  69                         assert(node->output_color_space == node_map[inputs[i]]->output_color_space);
  70                 }
  71         }
  72
  73         nodes.push_back(node);
  74         node_map[effect] = node;
  75 }
  76
  77 void EffectChain::find_all_nonlinear_inputs(EffectChain::Node *node,
  78                                             std::vector<EffectChain::Node *> *nonlinear_inputs,
  79                                             std::vector<EffectChain::Node *> *intermediates)
  80 {
  81         if (node->output_gamma_curve == GAMMA_LINEAR) {
  82                 return;
  83         }
  84         if (node->effect->num_inputs() == 0) {
  85                 nonlinear_inputs->push_back(node);
  86         } else {
  87                 intermediates->push_back(node);
  88                 assert(node->effect->num_inputs() == node->incoming_links.size());
  89                 for (unsigned i = 0; i < node->incoming_links.size(); ++i) {
  90                         find_all_nonlinear_inputs(node->incoming_links[i], nonlinear_inputs, intermediates);
  91                 }
  92         }
  93 }
  94
  95 EffectChain::Node *EffectChain::normalize_to_linear_gamma(EffectChain::Node *input)
  96 {
  97         // Find out if all the inputs can be set to deliver sRGB inputs.
  98         // If so, we can just ask them to do that instead of inserting a
  99         // (possibly expensive) conversion operation.
 100         //
 101         // NOTE: We assume that effects generally don't mess with the gamma
 102         // curve (except GammaCompressionEffect, which should never be
 103         // inserted into a chain when this is called), so that we can just
 104         // update the output gamma as we go.
 105         //
 106         // TODO: Setting this flag for one source might confuse a different
 107         // part of the pipeline using the same source.
 108         std::vector<Node *> nonlinear_inputs;
 109         std::vector<Node *> intermediates;
 110         find_all_nonlinear_inputs(input, &nonlinear_inputs, &intermediates);
 111
 112         bool all_ok = true;
 113         for (unsigned i = 0; i < nonlinear_inputs.size(); ++i) {
 114                 Input *input = static_cast<Input *>(nonlinear_inputs[i]->effect);
 115                 all_ok &= input->can_output_linear_gamma();
 116         }
 117
 118         if (all_ok) {
 119                 for (unsigned i = 0; i < nonlinear_inputs.size(); ++i) {
 120                         bool ok = nonlinear_inputs[i]->effect->set_int("output_linear_gamma", 1);
 121                         assert(ok);
 122                         nonlinear_inputs[i]->output_gamma_curve = GAMMA_LINEAR;
 123                 }
 124                 for (unsigned i = 0; i < intermediates.size(); ++i) {
 125                         intermediates[i]->output_gamma_curve = GAMMA_LINEAR;
 126                 }
 127                 return input;
 128         }
 129
 130         // OK, that didn't work. Insert a conversion effect.
 131         GammaExpansionEffect *gamma_conversion = new GammaExpansionEffect();
 132         gamma_conversion->set_int("source_curve", input->output_gamma_curve);
 133         std::vector<Effect *> inputs;
 134         inputs.push_back(input->effect);
 135         gamma_conversion->add_self_to_effect_chain(this, inputs);
 136
 137         assert(node_map.count(gamma_conversion) != 0);
 138         Node *node = node_map[gamma_conversion];
 139         node->output_gamma_curve = GAMMA_LINEAR;
 140         return node;
 141 }
 142
 143 EffectChain::Node *EffectChain::normalize_to_srgb(EffectChain::Node *input)
 144 {
 145         assert(input->output_gamma_curve == GAMMA_LINEAR);
 146         ColorSpaceConversionEffect *colorspace_conversion = new ColorSpaceConversionEffect();
 147         colorspace_conversion->set_int("source_space", input->output_color_space);
 148         colorspace_conversion->set_int("destination_space", COLORSPACE_sRGB);
 149         std::vector<Effect *> inputs;
 150         inputs.push_back(input->effect);
 151         colorspace_conversion->add_self_to_effect_chain(this, inputs);
 152
 153         assert(node_map.count(colorspace_conversion) != 0);
 154         Node *node = node_map[colorspace_conversion];
 155         node->output_color_space = COLORSPACE_sRGB;
 156         return node;
 157 }
 158
 159 Effect *EffectChain::add_effect(Effect *effect, const std::vector<Effect *> &inputs)
 160 {
 161         assert(inputs.size() == effect->num_inputs());
 162
 163         std::vector<Effect *> normalized_inputs = inputs;
 164         for (unsigned i = 0; i < normalized_inputs.size(); ++i) {
 165                 assert(node_map.count(normalized_inputs[i]) != 0);
 166                 Node *input = node_map[normalized_inputs[i]];
 167                 if (effect->needs_linear_light() && input->output_gamma_curve != GAMMA_LINEAR) {
 168                         input = normalize_to_linear_gamma(input);
 169                 }
 170                 if (effect->needs_srgb_primaries() && input->output_color_space != COLORSPACE_sRGB) {
 171                         input = normalize_to_srgb(input);
 172                 }
 173                 normalized_inputs[i] = input->effect;
 174         }
 175
 176         effect->add_self_to_effect_chain(this, normalized_inputs);
 177         return effect;
 178 }
 179
 180 // GLSL pre-1.30 doesn't support token pasting. Replace PREFIX(x) with <effect_id>_x.
 181 std::string replace_prefix(const std::string &text, const std::string &prefix)
 182 {
 183         std::string output;
 184         size_t start = 0;
 185
 186         while (start < text.size()) {
 187                 size_t pos = text.find("PREFIX(", start);
 188                 if (pos == std::string::npos) {
 189                         output.append(text.substr(start, std::string::npos));
 190                         break;
 191                 }
 192
 193                 output.append(text.substr(start, pos - start));
 194                 output.append(prefix);
 195                 output.append("_");
 196
 197                 pos += strlen("PREFIX(");
 198
 199                 // Output stuff until we find the matching ), which we then eat.
 200                 int depth = 1;
 201                 size_t end_arg_pos = pos;
 202                 while (end_arg_pos < text.size()) {
 203                         if (text[end_arg_pos] == '(') {
 204                                 ++depth;
 205                         } else if (text[end_arg_pos] == ')') {
 206                                 --depth;
 207                                 if (depth == 0) {
 208                                         break;
 209                                 }
 210                         }
 211                         ++end_arg_pos;
 212                 }
 213                 output.append(text.substr(pos, end_arg_pos - pos));
 214                 ++end_arg_pos;
 215                 assert(depth == 0);
 216                 start = end_arg_pos;
 217         }
 218         return output;
 219 }
 220
 221 EffectChain::Phase *EffectChain::compile_glsl_program(
 222         const std::vector<EffectChain::Node *> &inputs,
 223         const std::vector<EffectChain::Node *> &effects)
 224 {
 225         assert(!effects.empty());
 226
 227         // Deduplicate the inputs.
 228         std::vector<Node *> true_inputs = inputs;
 229         std::sort(true_inputs.begin(), true_inputs.end());
 230         true_inputs.erase(std::unique(true_inputs.begin(), true_inputs.end()), true_inputs.end());
 231
 232         bool input_needs_mipmaps = false;
 233         std::string frag_shader = read_file("header.frag");
 234
 235         // Create functions for all the texture inputs that we need.
 236         for (unsigned i = 0; i < true_inputs.size(); ++i) {
 237                 Node *input = true_inputs[i];
 238
 239                 frag_shader += std::string("uniform sampler2D tex_") + input->effect_id + ";\n";
 240                 frag_shader += std::string("vec4 ") + input->effect_id + "(vec2 tc) {\n";
 241                 frag_shader += "\treturn texture2D(tex_" + input->effect_id + ", tc);\n";
 242                 frag_shader += "}\n";
 243                 frag_shader += "\n";
 244         }
 245
 246         for (unsigned i = 0; i < effects.size(); ++i) {
 247                 Node *node = effects[i];
 248
 249                 if (node->incoming_links.size() == 1) {
 250                         frag_shader += std::string("#define INPUT ") + node->incoming_links[0]->effect_id + "\n";
 251                 } else {
 252                         for (unsigned j = 0; j < node->incoming_links.size(); ++j) {
 253                                 char buf[256];
 254                                 sprintf(buf, "#define INPUT%d %s\n", j + 1, node->incoming_links[j]->effect_id.c_str());
 255                                 frag_shader += buf;
 256                         }
 257                 }
 258
 259                 frag_shader += "\n";
 260                 frag_shader += std::string("#define FUNCNAME ") + node->effect_id + "\n";
 261                 frag_shader += replace_prefix(node->effect->output_convenience_uniforms(), node->effect_id);
 262                 frag_shader += replace_prefix(node->effect->output_fragment_shader(), node->effect_id);
 263                 frag_shader += "#undef PREFIX\n";
 264                 frag_shader += "#undef FUNCNAME\n";
 265                 if (node->incoming_links.size() == 1) {
 266                         frag_shader += "#undef INPUT\n";
 267                 } else {
 268                         for (unsigned j = 0; j < node->incoming_links.size(); ++j) {
 269                                 char buf[256];
 270                                 sprintf(buf, "#undef INPUT%d\n", j + 1);
 271                                 frag_shader += buf;
 272                         }
 273                 }
 274                 frag_shader += "\n";
 275
 276                 input_needs_mipmaps |= node->effect->needs_mipmaps();
 277         }
 278         for (unsigned i = 0; i < effects.size(); ++i) {
 279                 Node *node = effects[i];
 280                 if (node->effect->num_inputs() == 0) {
 281                         node->effect->set_int("needs_mipmaps", input_needs_mipmaps);
 282                 }
 283         }
 284         frag_shader += std::string("#define INPUT ") + effects.back()->effect_id + "\n";
 285         frag_shader.append(read_file("footer.frag"));
 286         printf("%s\n", frag_shader.c_str());
 287
 288         GLuint glsl_program_num = glCreateProgram();
 289         GLuint vs_obj = compile_shader(read_file("vs.vert"), GL_VERTEX_SHADER);
 290         GLuint fs_obj = compile_shader(frag_shader, GL_FRAGMENT_SHADER);
 291         glAttachShader(glsl_program_num, vs_obj);
 292         check_error();
 293         glAttachShader(glsl_program_num, fs_obj);
 294         check_error();
 295         glLinkProgram(glsl_program_num);
 296         check_error();
 297
 298         Phase *phase = new Phase;
 299         phase->glsl_program_num = glsl_program_num;
 300         phase->input_needs_mipmaps = input_needs_mipmaps;
 301         phase->inputs = true_inputs;
 302         phase->effects = effects;
 303
 304         return phase;
 305 }
 306
 307 // Construct GLSL programs, starting at the given effect and following
 308 // the chain from there. We end a program every time we come to an effect
 309 // marked as "needs texture bounce", one that is used by multiple other
 310 // effects, every time an effect wants to change the output size,
 311 // and of course at the end.
 312 //
 313 // We follow a quite simple depth-first search from the output, although
 314 // without any explicit recursion.
 315 void EffectChain::construct_glsl_programs(EffectChain::Node *output)
 316 {
 317         // Which effects have already been completed in this phase?
 318         // We need to keep track of it, as an effect with multiple outputs
 319         // could otherwise be calculate multiple times.
 320         std::set<Node *> completed_effects;
 321
 322         // Effects in the current phase, as well as inputs (outputs from other phases
 323         // that we depend on). Note that since we start iterating from the end,
 324         // the effect list will be in the reverse order.
 325         std::vector<Node *> this_phase_inputs;
 326         std::vector<Node *> this_phase_effects;
 327
 328         // Effects that we have yet to calculate, but that we know should
 329         // be in the current phase.
 330         std::stack<Node *> effects_todo_this_phase;
 331
 332         // Effects that we have yet to calculate, but that come from other phases.
 333         // We delay these until we have this phase done in its entirety,
 334         // at which point we pick any of them and start a new phase from that.
 335         std::stack<Node *> effects_todo_other_phases;
 336
 337         effects_todo_this_phase.push(output);
 338
 339         for ( ;; ) {  // Termination condition within loop.
 340                 if (!effects_todo_this_phase.empty()) {
 341                         // OK, we have more to do this phase.
 342                         Node *node = effects_todo_this_phase.top();
 343                         effects_todo_this_phase.pop();
 344
 345                         // This should currently only happen for effects that are phase outputs,
 346                         // and we throw those out separately below.
 347                         assert(completed_effects.count(node) == 0);
 348
 349                         this_phase_effects.push_back(node);
 350                         completed_effects.insert(node);
 351
 352                         // Find all the dependencies of this effect, and add them to the stack.
 353                         std::vector<Node *> deps = node->incoming_links;
 354                         assert(node->effect->num_inputs() == deps.size());
 355                         for (unsigned i = 0; i < deps.size(); ++i) {
 356                                 bool start_new_phase = false;
 357
 358                                 // FIXME: If we sample directly from a texture, we won't need this.
 359                                 if (node->effect->needs_texture_bounce()) {
 360                                         start_new_phase = true;
 361                                 }
 362
 363                                 if (deps[i]->outgoing_links.size() > 1 && deps[i]->effect->num_inputs() > 0) {
 364                                         // More than one effect uses this as the input,
 365                                         // and it is not a texture itself.
 366                                         // The easiest thing to do (and probably also the safest
 367                                         // performance-wise in most cases) is to bounce it to a texture
 368                                         // and then let the next passes read from that.
 369                                         start_new_phase = true;
 370                                 }
 371
 372                                 if (deps[i]->effect->changes_output_size()) {
 373                                         start_new_phase = true;
 374                                 }
 375
 376                                 if (start_new_phase) {
 377                                         effects_todo_other_phases.push(deps[i]);
 378                                         this_phase_inputs.push_back(deps[i]);
 379                                 } else {
 380                                         effects_todo_this_phase.push(deps[i]);
 381                                 }
 382                         }
 383                         continue;
 384                 }
 385
 386                 // No more effects to do this phase. Take all the ones we have,
 387                 // and create a GLSL program for it.
 388                 if (!this_phase_effects.empty()) {
 389                         reverse(this_phase_effects.begin(), this_phase_effects.end());
 390                         phases.push_back(compile_glsl_program(this_phase_inputs, this_phase_effects));
 391                         this_phase_effects.back()->phase = phases.back();
 392                         this_phase_inputs.clear();
 393                         this_phase_effects.clear();
 394                 }
 395                 assert(this_phase_inputs.empty());
 396                 assert(this_phase_effects.empty());
 397
 398                 // If we have no effects left, exit.
 399                 if (effects_todo_other_phases.empty()) {
 400                         break;
 401                 }
 402
 403                 Node *node = effects_todo_other_phases.top();
 404                 effects_todo_other_phases.pop();
 405
 406                 if (completed_effects.count(node) == 0) {
 407                         // Start a new phase, calculating from this effect.
 408                         effects_todo_this_phase.push(node);
 409                 }
 410         }
 411
 412         // Finally, since the phases are found from the output but must be executed
 413         // from the input(s), reverse them, too.
 414         std::reverse(phases.begin(), phases.end());
 415 }
 416
 417 void EffectChain::find_output_size(EffectChain::Phase *phase)
 418 {
 419         Node *output_node = phase->effects.back();
 420
 421         // If the last effect explicitly sets an output size,
 422         // use that.
 423         if (output_node->effect->changes_output_size()) {
 424                 output_node->effect->get_output_size(&phase->output_width, &phase->output_height);
 425                 return;
 426         }
 427
 428         // If not, look at the input phases, if any. We select the largest one
 429         // (really assuming they all have the same aspect currently), by pixel count.
 430         if (!phase->inputs.empty()) {
 431                 unsigned best_width = 0, best_height = 0;
 432                 for (unsigned i = 0; i < phase->inputs.size(); ++i) {
 433                         Node *input = phase->inputs[i];
 434                         assert(input->phase->output_width != 0);
 435                         assert(input->phase->output_height != 0);
 436                         if (input->phase->output_width * input->phase->output_height > best_width * best_height) {
 437                                 best_width = input->phase->output_width;
 438                                 best_height = input->phase->output_height;
 439                         }
 440                 }
 441                 assert(best_width != 0);
 442                 assert(best_height != 0);
 443                 phase->output_width = best_width;
 444                 phase->output_height = best_height;
 445                 return;
 446         }
 447
 448         // OK, no inputs. Just use the global width/height.
 449         // TODO: We probably want to use the texture's size eventually.
 450         phase->output_width = width;
 451         phase->output_height = height;
 452 }
 453
 454 void EffectChain::finalize()
 455 {
 456         // Find the output effect. This is, simply, one that has no outgoing links.
 457         // If there are multiple ones, the graph is malformed (we do not support
 458         // multiple outputs right now).
 459         std::vector<Node *> output_nodes;
 460         for (unsigned i = 0; i < nodes.size(); ++i) {
 461                 Node *node = nodes[i];
 462                 if (node->outgoing_links.empty()) {
 463                         output_nodes.push_back(node);
 464                 }
 465         }
 466         assert(output_nodes.size() == 1);
 467         Node *output_node = output_nodes[0];
 468
 469         // Add normalizers to get the output format right.
 470         if (output_node->output_color_space != output_format.color_space) {
 471                 ColorSpaceConversionEffect *colorspace_conversion = new ColorSpaceConversionEffect();
 472                 colorspace_conversion->set_int("source_space", output_node->output_color_space);
 473                 colorspace_conversion->set_int("destination_space", output_format.color_space);
 474                 std::vector<Effect *> inputs;
 475                 inputs.push_back(output_node->effect);
 476                 colorspace_conversion->add_self_to_effect_chain(this, inputs);
 477
 478                 assert(node_map.count(colorspace_conversion) != 0);
 479                 output_node = node_map[colorspace_conversion];
 480                 output_node->output_color_space = output_format.color_space;
 481         }
 482         if (output_node->output_gamma_curve != output_format.gamma_curve) {
 483                 if (output_node->output_gamma_curve != GAMMA_LINEAR) {
 484                         output_node = normalize_to_linear_gamma(output_node);
 485                 }
 486                 GammaCompressionEffect *gamma_conversion = new GammaCompressionEffect();
 487                 gamma_conversion->set_int("destination_curve", output_format.gamma_curve);
 488                 std::vector<Effect *> inputs;
 489                 inputs.push_back(output_node->effect);
 490                 gamma_conversion->add_self_to_effect_chain(this, inputs);
 491
 492                 assert(node_map.count(gamma_conversion) != 0);
 493                 output_node = node_map[gamma_conversion];
 494                 output_node->output_gamma_curve = output_format.gamma_curve;
 495         }
 496
 497         // Construct all needed GLSL programs, starting at the output.
 498         construct_glsl_programs(output_node);
 499
 500         // If we have more than one phase, we need intermediate render-to-texture.
 501         // Construct an FBO, and then as many textures as we need.
 502         // We choose the simplest option of having one texture per output,
 503         // since otherwise this turns into an (albeit simple)
 504         // register allocation problem.
 505         if (phases.size() > 1) {
 506                 glGenFramebuffers(1, &fbo);
 507
 508                 for (unsigned i = 0; i < phases.size() - 1; ++i) {
 509                         find_output_size(phases[i]);
 510
 511                         Node *output_node = phases[i]->effects.back();
 512                         glGenTextures(1, &output_node->output_texture);
 513                         check_error();
 514                         glBindTexture(GL_TEXTURE_2D, output_node->output_texture);
 515                         check_error();
 516                         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
 517                         check_error();
 518                         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 519                         check_error();
 520                         glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA16F_ARB, phases[i]->output_width, phases[i]->output_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
 521                         check_error();
 522
 523                         output_node->output_texture_width = phases[i]->output_width;
 524                         output_node->output_texture_height = phases[i]->output_height;
 525                 }
 526         }
 527
 528         for (unsigned i = 0; i < inputs.size(); ++i) {
 529                 inputs[i]->finalize();
 530         }
 531
 532         assert(phases[0]->inputs.empty());
 533
 534         finalized = true;
 535 }
 536
 537 void EffectChain::render_to_screen()
 538 {
 539         assert(finalized);
 540
 541         // Basic state.
 542         glDisable(GL_BLEND);
 543         check_error();
 544         glDisable(GL_DEPTH_TEST);
 545         check_error();
 546         glDepthMask(GL_FALSE);
 547         check_error();
 548
 549         glMatrixMode(GL_PROJECTION);
 550         glLoadIdentity();
 551         glOrtho(0.0, 1.0, 0.0, 1.0, 0.0, 1.0);
 552
 553         glMatrixMode(GL_MODELVIEW);
 554         glLoadIdentity();
 555
 556         if (phases.size() > 1) {
 557                 glBindFramebuffer(GL_FRAMEBUFFER, fbo);
 558                 check_error();
 559         }
 560
 561         std::set<Node *> generated_mipmaps;
 562
 563         for (unsigned phase = 0; phase < phases.size(); ++phase) {
 564                 // See if the requested output size has changed. If so, we need to recreate
 565                 // the texture (and before we start setting up inputs).
 566                 if (phase != phases.size() - 1) {
 567                         find_output_size(phases[phase]);
 568
 569                         Node *output_node = phases[phase]->effects.back();
 570
 571                         if (output_node->output_texture_width != phases[phase]->output_width ||
 572                             output_node->output_texture_height != phases[phase]->output_height) {
 573                                 glActiveTexture(GL_TEXTURE0);
 574                                 check_error();
 575                                 glBindTexture(GL_TEXTURE_2D, output_node->output_texture);
 576                                 check_error();
 577                                 glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA16F_ARB, phases[phase]->output_width, phases[phase]->output_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
 578                                 check_error();
 579                                 glBindTexture(GL_TEXTURE_2D, 0);
 580                                 check_error();
 581
 582                                 output_node->output_texture_width = phases[phase]->output_width;
 583                                 output_node->output_texture_height = phases[phase]->output_height;
 584                         }
 585                 }
 586
 587                 glUseProgram(phases[phase]->glsl_program_num);
 588                 check_error();
 589
 590                 // Set up RTT inputs for this phase.
 591                 for (unsigned sampler = 0; sampler < phases[phase]->inputs.size(); ++sampler) {
 592                         glActiveTexture(GL_TEXTURE0 + sampler);
 593                         Node *input = phases[phase]->inputs[sampler];
 594                         glBindTexture(GL_TEXTURE_2D, input->output_texture);
 595                         check_error();
 596                         if (phases[phase]->input_needs_mipmaps) {
 597                                 if (generated_mipmaps.count(input) == 0) {
 598                                         glGenerateMipmap(GL_TEXTURE_2D);
 599                                         check_error();
 600                                         generated_mipmaps.insert(input);
 601                                 }
 602                                 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_NEAREST);
 603                                 check_error();
 604                         } else {
 605                                 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
 606                                 check_error();
 607                         }
 608
 609                         std::string texture_name = std::string("tex_") + input->effect_id;
 610                         glUniform1i(glGetUniformLocation(phases[phase]->glsl_program_num, texture_name.c_str()), sampler);
 611                         check_error();
 612                 }
 613
 614                 // And now the output.
 615                 if (phase == phases.size() - 1) {
 616                         // Last phase goes directly to the screen.
 617                         glBindFramebuffer(GL_FRAMEBUFFER, 0);
 618                         check_error();
 619                         glViewport(0, 0, width, height);
 620                 } else {
 621                         Node *output_node = phases[phase]->effects.back();
 622                         glFramebufferTexture2D(
 623                                 GL_FRAMEBUFFER,
 624                                 GL_COLOR_ATTACHMENT0,
 625                                 GL_TEXTURE_2D,
 626                                 output_node->output_texture,
 627                                 0);
 628                         check_error();
 629                         glViewport(0, 0, phases[phase]->output_width, phases[phase]->output_height);
 630                 }
 631
 632                 // Give the required parameters to all the effects.
 633                 unsigned sampler_num = phases[phase]->inputs.size();
 634                 for (unsigned i = 0; i < phases[phase]->effects.size(); ++i) {
 635                         Node *node = phases[phase]->effects[i];
 636                         node->effect->set_gl_state(phases[phase]->glsl_program_num, node->effect_id, &sampler_num);
 637                         check_error();
 638                 }
 639
 640                 // Now draw!
 641                 glBegin(GL_QUADS);
 642
 643                 glTexCoord2f(0.0f, 0.0f);
 644                 glVertex2f(0.0f, 0.0f);
 645
 646                 glTexCoord2f(1.0f, 0.0f);
 647                 glVertex2f(1.0f, 0.0f);
 648
 649                 glTexCoord2f(1.0f, 1.0f);
 650                 glVertex2f(1.0f, 1.0f);
 651
 652                 glTexCoord2f(0.0f, 1.0f);
 653                 glVertex2f(0.0f, 1.0f);
 654
 655                 glEnd();
 656                 check_error();
 657
 658                 for (unsigned i = 0; i < phases[phase]->effects.size(); ++i) {
 659                         Node *node = phases[phase]->effects[i];
 660                         node->effect->clear_gl_state();
 661                 }
 662         }
 663 }