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

   1 #define GL_GLEXT_PROTOTYPES 1
   2 #define NO_SDL_GLEXT 1
   3
   4 #define WIDTH 1280
   5 #define HEIGHT 720
   6 #define BUFFER_OFFSET(i) ((char *)NULL + (i))
   7
   8 #include <string.h>
   9 #include <math.h>
  10 #include <time.h>
  11 #include <assert.h>
  12
  13 #include <string>
  14 #include <vector>
  15 #include <map>
  16
  17 #include <SDL/SDL.h>
  18 #include <SDL/SDL_opengl.h>
  19 #include <SDL/SDL_image.h>
  20
  21 #include <GL/gl.h>
  22 #include <GL/glext.h>
  23
  24 #include "util.h"
  25 #include "widgets.h"
  26 #include "texture_enum.h"
  27
  28 unsigned char result[WIDTH * HEIGHT * 4];
  29
  30 float lift_theta = 0.0f, lift_rad = 0.0f, lift_v = 0.0f;
  31 float gamma_theta = 0.0f, gamma_rad = 0.0f, gamma_v = 0.5f;
  32 float gain_theta = 0.0f, gain_rad = 0.0f, gain_v = 0.25f;
  33 float saturation = 1.0f;
  34
  35 float lift_r = 0.0f, lift_g = 0.0f, lift_b = 0.0f;
  36 float gamma_r = 1.0f, gamma_g = 1.0f, gamma_b = 1.0f;
  37 float gain_r = 1.0f, gain_g = 1.0f, gain_b = 1.0f;
  38
  39 enum PixelFormat { FORMAT_RGB, FORMAT_RGBA };
  40
  41 enum ColorSpace {
  42         COLORSPACE_sRGB = 0,
  43         COLORSPACE_REC_709 = 0,  // Same as sRGB.
  44         COLORSPACE_REC_601_525 = 1,
  45         COLORSPACE_REC_601_625 = 2,
  46 };
  47
  48 enum GammaCurve {
  49         GAMMA_LINEAR = 0,
  50         GAMMA_sRGB = 1,
  51         GAMMA_REC_601 = 2,
  52         GAMMA_REC_709 = 2,  // Same as Rec. 601.
  53 };
  54
  55 struct ImageFormat {
  56         PixelFormat pixel_format;
  57         ColorSpace color_space;
  58         GammaCurve gamma_curve;
  59 };
  60
  61 enum EffectId {
  62         // Mostly for internal use.
  63         GAMMA_CONVERSION = 0,
  64         RGB_PRIMARIES_CONVERSION,
  65
  66         // Color.
  67         LIFT_GAMMA_GAIN,
  68 };
  69
  70 class Effect {
  71 public:
  72         virtual bool needs_linear_light() { return true; }
  73         virtual bool needs_srgb_primaries() { return true; }
  74         virtual bool needs_many_samples() { return false; }
  75         virtual bool needs_mipmaps() { return false; }
  76
  77         // Neither of these take ownership.
  78         bool set_int(const std::string&, int value);
  79         bool set_float(const std::string &key, float value);
  80         bool set_vec3(const std::string &key, const float *values);
  81
  82 protected:
  83         // Neither of these take ownership.
  84         void register_int(const std::string &key, int *value);
  85         void register_float(const std::string &key, float *value);
  86         void register_vec3(const std::string &key, float *values);
  87
  88 private:
  89         std::map<std::string, int *> params_int;
  90         std::map<std::string, float *> params_float;
  91         std::map<std::string, float *> params_vec3;
  92 };
  93
  94 bool Effect::set_int(const std::string &key, int value)
  95 {
  96         if (params_int.count(key) == 0) {
  97                 return false;
  98         }
  99         *params_int[key] = value;
 100         return true;
 101 }
 102
 103 bool Effect::set_float(const std::string &key, float value)
 104 {
 105         if (params_float.count(key) == 0) {
 106                 return false;
 107         }
 108         *params_float[key] = value;
 109         return true;
 110 }
 111
 112 bool Effect::set_vec3(const std::string &key, const float *values)
 113 {
 114         if (params_vec3.count(key) == 0) {
 115                 return false;
 116         }
 117         memcpy(params_vec3[key], values, sizeof(float) * 3);
 118         return true;
 119 }
 120
 121 void Effect::register_int(const std::string &key, int *value)
 122 {
 123         assert(params_int.count(key) == 0);
 124         params_int[key] = value;
 125 }
 126
 127 void Effect::register_float(const std::string &key, float *value)
 128 {
 129         assert(params_float.count(key) == 0);
 130         params_float[key] = value;
 131 }
 132
 133 void Effect::register_vec3(const std::string &key, float *values)
 134 {
 135         assert(params_vec3.count(key) == 0);
 136         params_vec3[key] = values;
 137 }
 138
 139 // Can alias on a float[3].
 140 struct RGBTriplet {
 141         RGBTriplet(float r, float g, float b)
 142                 : r(r), g(g), b(b) {}
 143
 144         float r, g, b;
 145 };
 146
 147 class GammaExpansionEffect : public Effect {
 148 public:
 149         GammaExpansionEffect()
 150                 : source_curve(GAMMA_LINEAR)
 151         {
 152                 register_int("source_curve", (int *)&source_curve);
 153         }
 154
 155 private:
 156         GammaCurve source_curve;
 157 };
 158
 159 class ColorSpaceConversionEffect : public Effect {
 160 public:
 161         ColorSpaceConversionEffect()
 162                 : source_space(COLORSPACE_sRGB),
 163                   destination_space(COLORSPACE_sRGB)
 164         {
 165                 register_int("source_space", (int *)&source_space);
 166                 register_int("destination_space", (int *)&destination_space);
 167         }
 168
 169 private:
 170         ColorSpace source_space, destination_space;
 171 };
 172
 173 class ColorSpaceConversionEffect;
 174
 175 class LiftGammaGainEffect : public Effect {
 176 public:
 177         LiftGammaGainEffect()
 178                 : lift(0.0f, 0.0f, 0.0f),
 179                   gamma(1.0f, 1.0f, 1.0f),
 180                   gain(1.0f, 1.0f, 1.0f),
 181                   saturation(1.0f)
 182         {
 183                 register_vec3("lift", (float *)&lift);
 184                 register_vec3("gamma", (float *)&gamma);
 185                 register_vec3("gain", (float *)&gain);
 186                 register_float("saturation", &saturation);
 187         }
 188
 189 private:
 190         RGBTriplet lift, gamma, gain;
 191         float saturation;
 192 };
 193
 194 class EffectChain {
 195 public:
 196         EffectChain(unsigned width, unsigned height);
 197         void add_input(const ImageFormat &format);
 198
 199         // The pointer is owned by EffectChain.
 200         Effect *add_effect(EffectId effect);
 201
 202         void add_output(const ImageFormat &format);
 203
 204         void render(unsigned char *src, unsigned char *dst);
 205
 206 private:
 207         unsigned width, height;
 208         ImageFormat input_format, output_format;
 209         std::vector<Effect *> effects;
 210
 211         ColorSpace current_color_space;
 212         GammaCurve current_gamma_curve;
 213 };
 214
 215 EffectChain::EffectChain(unsigned width, unsigned height)
 216         : width(width), height(height) {}
 217
 218 void EffectChain::add_input(const ImageFormat &format)
 219 {
 220         input_format = format;
 221         current_color_space = format.color_space;
 222         current_gamma_curve = format.gamma_curve;
 223 }
 224
 225 void EffectChain::add_output(const ImageFormat &format)
 226 {
 227         output_format = format;
 228 }
 229
 230 Effect *instantiate_effect(EffectId effect)
 231 {
 232         switch (effect) {
 233         case GAMMA_CONVERSION:
 234                 return new GammaExpansionEffect();
 235         case RGB_PRIMARIES_CONVERSION:
 236                 return new GammaExpansionEffect();
 237         case LIFT_GAMMA_GAIN:
 238                 return new LiftGammaGainEffect();
 239         }
 240         assert(false);
 241 }
 242
 243 Effect *EffectChain::add_effect(EffectId effect_id)
 244 {
 245         Effect *effect = instantiate_effect(effect_id);
 246
 247         if (effect->needs_linear_light() && current_gamma_curve != GAMMA_LINEAR) {
 248                 GammaExpansionEffect *gamma_conversion = new GammaExpansionEffect();
 249                 gamma_conversion->set_int("source_curve", current_gamma_curve);
 250                 effects.push_back(gamma_conversion);
 251                 current_gamma_curve = GAMMA_LINEAR;
 252         }
 253
 254         if (effect->needs_srgb_primaries() && current_color_space != COLORSPACE_sRGB) {
 255                 assert(current_gamma_curve == GAMMA_LINEAR);
 256                 ColorSpaceConversionEffect *colorspace_conversion = new ColorSpaceConversionEffect();
 257                 colorspace_conversion->set_int("source_space", current_color_space);
 258                 colorspace_conversion->set_int("destination_space", COLORSPACE_sRGB);
 259                 effects.push_back(colorspace_conversion);
 260                 current_color_space = COLORSPACE_sRGB;
 261         }
 262
 263         effects.push_back(effect);
 264         return effect;
 265 }
 266
 267 GLhandleARB read_shader(const char* filename, GLenum type)
 268 {
 269         static char buf[131072];
 270         FILE *fp = fopen(filename, "r");
 271         if (fp == NULL) {
 272                 perror(filename);
 273                 exit(1);
 274         }
 275
 276         int len = fread(buf, 1, sizeof(buf), fp);
 277         fclose(fp);
 278
 279         GLhandleARB obj = glCreateShaderObjectARB(type);
 280         const GLchar* source[] = { buf };
 281         const GLint length[] = { len };
 282         glShaderSource(obj, 1, source, length);
 283         glCompileShader(obj);
 284
 285         GLchar info_log[4096];
 286         GLsizei log_length = sizeof(info_log) - 1;
 287         glGetShaderInfoLog(obj, log_length, &log_length, info_log);
 288         info_log[log_length] = 0;
 289         printf("shader compile log: %s\n", info_log);
 290
 291         GLint status;
 292         glGetShaderiv(obj, GL_COMPILE_STATUS, &status);
 293         if (status == GL_FALSE) {
 294                 exit(1);
 295         }
 296
 297         return obj;
 298 }
 299
 300 void draw_picture_quad(GLint prog, int frame)
 301 {
 302         glUseProgramObjectARB(prog);
 303         check_error();
 304
 305         glActiveTexture(GL_TEXTURE0);
 306         glBindTexture(GL_TEXTURE_2D, SOURCE_IMAGE);
 307         glUniform1i(glGetUniformLocation(prog, "tex"), 0);
 308
 309         glActiveTexture(GL_TEXTURE1);
 310         glBindTexture(GL_TEXTURE_1D, SRGB_LUT);
 311         glUniform1i(glGetUniformLocation(prog, "srgb_tex"), 1);
 312
 313         glActiveTexture(GL_TEXTURE2);
 314         glBindTexture(GL_TEXTURE_1D, SRGB_REVERSE_LUT);
 315         glUniform1i(glGetUniformLocation(prog, "srgb_reverse_tex"), 2);
 316
 317         glUniform3f(glGetUniformLocation(prog, "lift"), lift_r, lift_g, lift_b);
 318         //glUniform3f(glGetUniformLocation(prog, "gamma"), gamma_r, gamma_g, gamma_b);
 319         glUniform3f(glGetUniformLocation(prog, "inv_gamma_22"),
 320                     2.2f / gamma_r,
 321                     2.2f / gamma_g,
 322                     2.2f / gamma_b);
 323         glUniform3f(glGetUniformLocation(prog, "gain_pow_inv_gamma"),
 324                     pow(gain_r, 1.0f / gamma_r),
 325                     pow(gain_g, 1.0f / gamma_g),
 326                     pow(gain_b, 1.0f / gamma_b));
 327         glUniform1f(glGetUniformLocation(prog, "saturation"), saturation);
 328
 329         glDisable(GL_BLEND);
 330         check_error();
 331         glDisable(GL_DEPTH_TEST);
 332         check_error();
 333         glDepthMask(GL_FALSE);
 334         check_error();
 335
 336         glMatrixMode(GL_PROJECTION);
 337         glLoadIdentity();
 338         glOrtho(0.0, 1.0, 0.0, 1.0, 0.0, 1.0);
 339
 340         glMatrixMode(GL_MODELVIEW);
 341         glLoadIdentity();
 342
 343         glClearColor(1.0f, 0.0f, 0.0f, 1.0f);
 344 //      glClear(GL_COLOR_BUFFER_BIT);
 345         check_error();
 346
 347         glBegin(GL_QUADS);
 348
 349         glTexCoord2f(0.0f, 1.0f);
 350         glVertex2f(0.0f, 0.0f);
 351
 352         glTexCoord2f(1.0f, 1.0f);
 353         glVertex2f(1.0f, 0.0f);
 354
 355         glTexCoord2f(1.0f, 0.0f);
 356         glVertex2f(1.0f, 1.0f);
 357
 358         glTexCoord2f(0.0f, 0.0f);
 359         glVertex2f(0.0f, 1.0f);
 360
 361         glEnd();
 362         check_error();
 363 }
 364
 365 void update_hsv()
 366 {
 367         hsv2rgb(lift_theta, lift_rad, lift_v, &lift_r, &lift_g, &lift_b);
 368         hsv2rgb(gamma_theta, gamma_rad, gamma_v * 2.0f, &gamma_r, &gamma_g, &gamma_b);
 369         hsv2rgb(gain_theta, gain_rad, gain_v * 4.0f, &gain_r, &gain_g, &gain_b);
 370
 371         if (saturation < 0.0) {
 372                 saturation = 0.0;
 373         }
 374
 375         printf("lift: %f %f %f\n", lift_r, lift_g, lift_b);
 376         printf("gamma: %f %f %f\n", gamma_r, gamma_g, gamma_b);
 377         printf("gain: %f %f %f\n", gain_r, gain_g, gain_b);
 378         printf("saturation: %f\n", saturation);
 379         printf("\n");
 380 }
 381
 382 void mouse(int x, int y)
 383 {
 384         float xf = (x / (float)WIDTH) * 16.0f / 9.0f;
 385         float yf = (HEIGHT - y) / (float)HEIGHT;
 386
 387         if (yf < 0.2f) {
 388                 read_colorwheel(xf, yf, &lift_rad, &lift_theta, &lift_v);
 389         } else if (yf >= 0.2f && yf < 0.4f) {
 390                 read_colorwheel(xf, yf - 0.2f, &gamma_rad, &gamma_theta, &gamma_v);
 391         } else if (yf >= 0.4f && yf < 0.6f) {
 392                 read_colorwheel(xf, yf - 0.4f, &gain_rad, &gain_theta, &gain_v);
 393         } else if (yf >= 0.6f && yf < 0.62f && xf < 0.2f) {
 394                 saturation = (xf / 0.2f) * 4.0f;
 395         }
 396
 397         update_hsv();
 398 }
 399
 400 void load_texture(const char *filename)
 401 {
 402         SDL_Surface *img = IMG_Load(filename);
 403         if (img == NULL) {
 404                 fprintf(stderr, "Load of '%s' failed\n", filename);
 405                 exit(1);
 406         }
 407
 408         // Convert to RGB.
 409         SDL_PixelFormat *fmt = img->format;
 410         SDL_LockSurface(img);
 411         unsigned char *src_pixels = (unsigned char *)img->pixels;
 412         unsigned char *dst_pixels = (unsigned char *)malloc(img->w * img->h * 3);
 413         for (unsigned i = 0; i < img->w * img->h; ++i) {
 414                 unsigned char r, g, b;
 415                 unsigned int temp;
 416                 unsigned int pixel = *(unsigned int *)(src_pixels + i * fmt->BytesPerPixel);
 417
 418                 temp = pixel & fmt->Rmask;
 419                 temp = temp >> fmt->Rshift;
 420                 temp = temp << fmt->Rloss;
 421                 r = temp;
 422
 423                 temp = pixel & fmt->Gmask;
 424                 temp = temp >> fmt->Gshift;
 425                 temp = temp << fmt->Gloss;
 426                 g = temp;
 427
 428                 temp = pixel & fmt->Bmask;
 429                 temp = temp >> fmt->Bshift;
 430                 temp = temp << fmt->Bloss;
 431                 b = temp;
 432
 433                 dst_pixels[i * 3 + 0] = r;
 434                 dst_pixels[i * 3 + 1] = g;
 435                 dst_pixels[i * 3 + 2] = b;
 436         }
 437         SDL_UnlockSurface(img);
 438
 439 #if 1
 440         // we will convert to sRGB in the shader
 441         glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, img->w, img->h, 0, GL_RGB, GL_UNSIGNED_BYTE, dst_pixels);
 442         check_error();
 443 #else
 444         // implicit sRGB conversion in hardware
 445         glTexImage2D(GL_TEXTURE_2D, 0, GL_SRGB8, img->w, img->h, 0, GL_RGB, GL_UNSIGNED_BYTE, dst_pixels);
 446         check_error();
 447 #endif
 448         free(dst_pixels);
 449         SDL_FreeSurface(img);
 450 }
 451
 452 void write_ppm(const char *filename, unsigned char *screenbuf)
 453 {
 454         FILE *fp = fopen(filename, "w");
 455         fprintf(fp, "P6\n%d %d\n255\n", WIDTH, HEIGHT);
 456         for (unsigned y = 0; y < HEIGHT; ++y) {
 457                 unsigned char *srcptr = screenbuf + ((HEIGHT - y - 1) * WIDTH) * 4;
 458                 for (unsigned x = 0; x < WIDTH; ++x) {
 459                         fputc(srcptr[x * 4 + 2], fp);
 460                         fputc(srcptr[x * 4 + 1], fp);
 461                         fputc(srcptr[x * 4 + 0], fp);
 462                 }
 463         }
 464         fclose(fp);
 465 }
 466
 467 int main(int argc, char **argv)
 468 {
 469         int quit = 0;
 470
 471         SDL_Init(SDL_INIT_EVERYTHING);
 472         SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 0);
 473         SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, 0);
 474         SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
 475         SDL_SetVideoMode(WIDTH, HEIGHT, 0, SDL_OPENGL);
 476         SDL_WM_SetCaption("OpenGL window", NULL);
 477
 478         // geez
 479         glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
 480         glPixelStorei(GL_PACK_ALIGNMENT, 1);
 481
 482         glBindTexture(GL_TEXTURE_2D, SOURCE_IMAGE);
 483         check_error();
 484         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
 485         check_error();
 486
 487         load_texture("blg_wheels_woman_1.jpg");
 488         //glGenerateMipmap(GL_TEXTURE_2D);
 489         //glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, 4);
 490         //check_error();
 491
 492         //load_texture("maserati_gts_wallpaper_1280x720_01.jpg");
 493         //load_texture("90630d1295075297-console-games-wallpapers-wallpaper_need_for_speed_prostreet_09_1920x1080.jpg");
 494         //load_texture("glacier-lake-1280-720-4087.jpg");
 495
 496 #if 0
 497         // sRGB reverse LUT
 498         glBindTexture(GL_TEXTURE_1D, SRGB_REVERSE_LUT);
 499         check_error();
 500         glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
 501         glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
 502         check_error();
 503         float srgb_reverse_tex[4096];
 504         for (unsigned i = 0; i < 4096; ++i) {
 505                 float x = i / 4095.0;
 506                 if (x < 0.0031308f) {
 507                         srgb_reverse_tex[i] = 12.92f * x;
 508                 } else {
 509                         srgb_reverse_tex[i] = 1.055f * pow(x, 1.0f / 2.4f) - 0.055f;
 510                 }
 511         }
 512         glTexImage1D(GL_TEXTURE_1D, 0, GL_LUMINANCE16F_ARB, 4096, 0, GL_LUMINANCE, GL_FLOAT, srgb_reverse_tex);
 513         check_error();
 514
 515         // sRGB LUT
 516         glBindTexture(GL_TEXTURE_1D, SRGB_LUT);
 517         check_error();
 518         glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
 519         glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
 520         check_error();
 521         float srgb_tex[256];
 522         for (unsigned i = 0; i < 256; ++i) {
 523                 float x = i / 255.0;
 524                 if (x < 0.04045f) {
 525                         srgb_tex[i] = x * (1.0f / 12.92f);
 526                 } else {
 527                         srgb_tex[i] = pow((x + 0.055) * (1.0 / 1.055f), 2.4);
 528                 }
 529         }
 530         glTexImage1D(GL_TEXTURE_1D, 0, GL_LUMINANCE16F_ARB, 256, 0, GL_LUMINANCE, GL_FLOAT, srgb_tex);
 531         check_error();
 532 #endif
 533
 534         // generate a PDO to hold the data we read back with glReadPixels()
 535         // (Intel/DRI goes into a slow path if we don't read to PDO)
 536         glBindBuffer(GL_PIXEL_PACK_BUFFER_ARB, 1);
 537         glBufferData(GL_PIXEL_PACK_BUFFER_ARB, WIDTH * HEIGHT * 4, NULL, GL_STREAM_READ);
 538
 539         make_hsv_wheel_texture();
 540         update_hsv();
 541
 542         int prog = glCreateProgram();
 543         GLhandleARB vs_obj = read_shader("vs.glsl", GL_VERTEX_SHADER);
 544         GLhandleARB fs_obj = read_shader("fs.glsl", GL_FRAGMENT_SHADER);
 545         glAttachObjectARB(prog, vs_obj);
 546         check_error();
 547         glAttachObjectARB(prog, fs_obj);
 548         check_error();
 549         glLinkProgram(prog);
 550         check_error();
 551
 552         GLchar info_log[4096];
 553         GLsizei log_length = sizeof(info_log) - 1;
 554         log_length = sizeof(info_log) - 1;
 555         glGetProgramInfoLog(prog, log_length, &log_length, info_log);
 556         info_log[log_length] = 0;
 557         printf("link: %s\n", info_log);
 558
 559         struct timespec start, now;
 560         int frame = 0, screenshot = 0;
 561         clock_gettime(CLOCK_MONOTONIC, &start);
 562
 563         while (!quit) {
 564                 SDL_Event event;
 565                 while (SDL_PollEvent(&event)) {
 566                         if (event.type == SDL_QUIT) {
 567                                 quit = 1;
 568                         } else if (event.type == SDL_KEYDOWN && event.key.keysym.sym == SDLK_ESCAPE) {
 569                                 quit = 1;
 570                         } else if (event.type == SDL_KEYDOWN && event.key.keysym.sym == SDLK_F1) {
 571                                 screenshot = 1;
 572                         } else if (event.type == SDL_MOUSEBUTTONDOWN && event.button.button == SDL_BUTTON_LEFT) {
 573                                 mouse(event.button.x, event.button.y);
 574                         } else if (event.type == SDL_MOUSEMOTION && (event.motion.state & SDL_BUTTON(1))) {
 575                                 mouse(event.motion.x, event.motion.y);
 576                         }
 577                 }
 578
 579                 ++frame;
 580
 581                 draw_picture_quad(prog, frame);
 582
 583                 glReadPixels(0, 0, WIDTH, HEIGHT, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, BUFFER_OFFSET(0));
 584                 check_error();
 585
 586                 draw_hsv_wheel(0.0f, lift_rad, lift_theta, lift_v);
 587                 draw_hsv_wheel(0.2f, gamma_rad, gamma_theta, gamma_v);
 588                 draw_hsv_wheel(0.4f, gain_rad, gain_theta, gain_v);
 589                 draw_saturation_bar(0.6f, saturation);
 590
 591                 SDL_GL_SwapBuffers();
 592                 check_error();
 593
 594                 unsigned char *screenbuf = (unsigned char *)glMapBuffer(GL_PIXEL_PACK_BUFFER_ARB, GL_READ_ONLY);
 595                 check_error();
 596                 if (screenshot) {
 597                         char filename[256];
 598                         sprintf(filename, "frame%05d.ppm", frame);
 599                         write_ppm(filename, screenbuf);
 600                         printf("Screenshot: %s\n", filename);
 601                         screenshot = 0;
 602                 }
 603                 glUnmapBuffer(GL_PIXEL_PACK_BUFFER_ARB);
 604                 check_error();
 605
 606 #if 1
 607                 clock_gettime(CLOCK_MONOTONIC, &now);
 608                 double elapsed = now.tv_sec - start.tv_sec +
 609                         1e-9 * (now.tv_nsec - start.tv_nsec);
 610                 printf("%d frames in %.3f seconds = %.1f fps (%.1f ms/frame)\n",
 611                         frame, elapsed, frame / elapsed,
 612                         1e3 * elapsed / frame);
 613 #endif
 614         }
 615         return 0;
 616 }