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