SDL2: test/testshader.c

"Fossies" - the Fresh Open Source Software Archive

Member "SDL2-2.28.5/test/testshader.c" (2 Nov 2023, 16939 Bytes) of package /linux/misc/SDL2-2.28.5.tar.gz:

As a special service "Fossies" has tried to format the requested source page into HTML format using (guessed) C and C++ source code syntax highlighting (style: standard) with prefixed line numbers and code folding option. Alternatively you can here view or download the uninterpreted source code file. See also the last Fossies "Diffs" side-by-side code changes report for "testshader.c":

2.26.5_vs_2.27.1.

1 /* 2 Copyright (C) 1997-2023 Sam Lantinga <slouken@libsdl.org> 3 4 This software is provided 'as-is', without any express or implied 5 warranty. In no event will the authors be held liable for any damages 6 arising from the use of this software. 7 8 Permission is granted to anyone to use this software for any purpose, 9 including commercial applications, and to alter it and redistribute it 10 freely. 11 */ 12 /* This is a simple example of using GLSL shaders with SDL */ 13 14 #include "SDL.h" 15 16 #ifdef HAVE_OPENGL 17 18 #include "SDL_opengl.h" 19 20 static SDL_bool shaders_supported; 21 static int current_shader = 0; 22 23 enum 24 { 25 SHADER_COLOR, 26 SHADER_TEXTURE, 27 SHADER_TEXCOORDS, 28 NUM_SHADERS 29 }; 30 31 typedef struct 32 { 33 GLhandleARB program; 34 GLhandleARB vert_shader; 35 GLhandleARB frag_shader; 36 const char *vert_source; 37 const char *frag_source; 38 } ShaderData; 39 40 static ShaderData shaders[NUM_SHADERS] = { 41 42 /* SHADER_COLOR */ 43 { 0, 0, 0, 44 /* vertex shader */ 45 "varying vec4 v_color;\n" 46 "\n" 47 "void main()\n" 48 "{\n" 49 " gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;\n" 50 " v_color = gl_Color;\n" 51 "}", 52 /* fragment shader */ 53 "varying vec4 v_color;\n" 54 "\n" 55 "void main()\n" 56 "{\n" 57 " gl_FragColor = v_color;\n" 58 "}" }, 59 60 /* SHADER_TEXTURE */ 61 { 0, 0, 0, 62 /* vertex shader */ 63 "varying vec4 v_color;\n" 64 "varying vec2 v_texCoord;\n" 65 "\n" 66 "void main()\n" 67 "{\n" 68 " gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;\n" 69 " v_color = gl_Color;\n" 70 " v_texCoord = vec2(gl_MultiTexCoord0);\n" 71 "}", 72 /* fragment shader */ 73 "varying vec4 v_color;\n" 74 "varying vec2 v_texCoord;\n" 75 "uniform sampler2D tex0;\n" 76 "\n" 77 "void main()\n" 78 "{\n" 79 " gl_FragColor = texture2D(tex0, v_texCoord) * v_color;\n" 80 "}" }, 81 82 /* SHADER_TEXCOORDS */ 83 { 0, 0, 0, 84 /* vertex shader */ 85 "varying vec2 v_texCoord;\n" 86 "\n" 87 "void main()\n" 88 "{\n" 89 " gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;\n" 90 " v_texCoord = vec2(gl_MultiTexCoord0);\n" 91 "}", 92 /* fragment shader */ 93 "varying vec2 v_texCoord;\n" 94 "\n" 95 "void main()\n" 96 "{\n" 97 " vec4 color;\n" 98 " vec2 delta;\n" 99 " float dist;\n" 100 "\n" 101 " delta = vec2(0.5, 0.5) - v_texCoord;\n" 102 " dist = dot(delta, delta);\n" 103 "\n" 104 " color.r = v_texCoord.x;\n" 105 " color.g = v_texCoord.x * v_texCoord.y;\n" 106 " color.b = v_texCoord.y;\n" 107 " color.a = 1.0 - (dist * 4.0);\n" 108 " gl_FragColor = color;\n" 109 "}" }, 110 }; 111 112 static PFNGLATTACHOBJECTARBPROC glAttachObjectARB; 113 static PFNGLCOMPILESHADERARBPROC glCompileShaderARB; 114 static PFNGLCREATEPROGRAMOBJECTARBPROC glCreateProgramObjectARB; 115 static PFNGLCREATESHADEROBJECTARBPROC glCreateShaderObjectARB; 116 static PFNGLDELETEOBJECTARBPROC glDeleteObjectARB; 117 static PFNGLGETINFOLOGARBPROC glGetInfoLogARB; 118 static PFNGLGETOBJECTPARAMETERIVARBPROC glGetObjectParameterivARB; 119 static PFNGLGETUNIFORMLOCATIONARBPROC glGetUniformLocationARB; 120 static PFNGLLINKPROGRAMARBPROC glLinkProgramARB; 121 static PFNGLSHADERSOURCEARBPROC glShaderSourceARB; 122 static PFNGLUNIFORM1IARBPROC glUniform1iARB; 123 static PFNGLUSEPROGRAMOBJECTARBPROC glUseProgramObjectARB; 124 125 static SDL_bool CompileShader(GLhandleARB shader, const char *source) 126 { 127 GLint status = 0; 128 129 glShaderSourceARB(shader, 1, &source, NULL); 130 glCompileShaderARB(shader); 131 glGetObjectParameterivARB(shader, GL_OBJECT_COMPILE_STATUS_ARB, &status); 132 if (status == 0) { 133 GLint length = 0; 134 char *info; 135 136 glGetObjectParameterivARB(shader, GL_OBJECT_INFO_LOG_LENGTH_ARB, &length); 137 info = (char *)SDL_malloc((size_t)length + 1); 138 if (info == NULL) { 139 SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Out of memory!"); 140 } else { 141 glGetInfoLogARB(shader, length, NULL, info); 142 SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Failed to compile shader:\n%s\n%s", source, info); 143 SDL_free(info); 144 } 145 return SDL_FALSE; 146 } else { 147 return SDL_TRUE; 148 } 149 } 150 151 static SDL_bool LinkProgram(ShaderData *data) 152 { 153 GLint status = 0; 154 155 glAttachObjectARB(data->program, data->vert_shader); 156 glAttachObjectARB(data->program, data->frag_shader); 157 glLinkProgramARB(data->program); 158 159 glGetObjectParameterivARB(data->program, GL_OBJECT_LINK_STATUS_ARB, &status); 160 if (status == 0) { 161 GLint length = 0; 162 char *info; 163 164 glGetObjectParameterivARB(data->program, GL_OBJECT_INFO_LOG_LENGTH_ARB, &length); 165 info = (char *)SDL_malloc((size_t)length + 1); 166 if (info == NULL) { 167 SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Out of memory!"); 168 } else { 169 glGetInfoLogARB(data->program, length, NULL, info); 170 SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Failed to link program:\n%s", info); 171 SDL_free(info); 172 } 173 return SDL_FALSE; 174 } else { 175 return SDL_TRUE; 176 } 177 } 178 179 static SDL_bool CompileShaderProgram(ShaderData *data) 180 { 181 const int num_tmus_bound = 4; 182 int i; 183 GLint location; 184 185 glGetError(); 186 187 /* Create one program object to rule them all */ 188 data->program = glCreateProgramObjectARB(); 189 190 /* Create the vertex shader */ 191 data->vert_shader = glCreateShaderObjectARB(GL_VERTEX_SHADER_ARB); 192 if (!CompileShader(data->vert_shader, data->vert_source)) { 193 return SDL_FALSE; 194 } 195 196 /* Create the fragment shader */ 197 data->frag_shader = glCreateShaderObjectARB(GL_FRAGMENT_SHADER_ARB); 198 if (!CompileShader(data->frag_shader, data->frag_source)) { 199 return SDL_FALSE; 200 } 201 202 /* ... and in the darkness bind them */ 203 if (!LinkProgram(data)) { 204 return SDL_FALSE; 205 } 206 207 /* Set up some uniform variables */ 208 glUseProgramObjectARB(data->program); 209 for (i = 0; i < num_tmus_bound; ++i) { 210 char tex_name[5]; 211 (void)SDL_snprintf(tex_name, SDL_arraysize(tex_name), "tex%d", i); 212 location = glGetUniformLocationARB(data->program, tex_name); 213 if (location >= 0) { 214 glUniform1iARB(location, i); 215 } 216 } 217 glUseProgramObjectARB(0); 218 219 return (glGetError() == GL_NO_ERROR) ? SDL_TRUE : SDL_FALSE; 220 } 221 222 static void DestroyShaderProgram(ShaderData *data) 223 { 224 if (shaders_supported) { 225 glDeleteObjectARB(data->vert_shader); 226 glDeleteObjectARB(data->frag_shader); 227 glDeleteObjectARB(data->program); 228 } 229 } 230 231 static SDL_bool InitShaders() 232 { 233 int i; 234 235 /* Check for shader support */ 236 shaders_supported = SDL_FALSE; 237 if (SDL_GL_ExtensionSupported("GL_ARB_shader_objects") && 238 SDL_GL_ExtensionSupported("GL_ARB_shading_language_100") && 239 SDL_GL_ExtensionSupported("GL_ARB_vertex_shader") && 240 SDL_GL_ExtensionSupported("GL_ARB_fragment_shader")) { 241 glAttachObjectARB = (PFNGLATTACHOBJECTARBPROC)SDL_GL_GetProcAddress("glAttachObjectARB"); 242 glCompileShaderARB = (PFNGLCOMPILESHADERARBPROC)SDL_GL_GetProcAddress("glCompileShaderARB"); 243 glCreateProgramObjectARB = (PFNGLCREATEPROGRAMOBJECTARBPROC)SDL_GL_GetProcAddress("glCreateProgramObjectARB"); 244 glCreateShaderObjectARB = (PFNGLCREATESHADEROBJECTARBPROC)SDL_GL_GetProcAddress("glCreateShaderObjectARB"); 245 glDeleteObjectARB = (PFNGLDELETEOBJECTARBPROC)SDL_GL_GetProcAddress("glDeleteObjectARB"); 246 glGetInfoLogARB = (PFNGLGETINFOLOGARBPROC)SDL_GL_GetProcAddress("glGetInfoLogARB"); 247 glGetObjectParameterivARB = (PFNGLGETOBJECTPARAMETERIVARBPROC)SDL_GL_GetProcAddress("glGetObjectParameterivARB"); 248 glGetUniformLocationARB = (PFNGLGETUNIFORMLOCATIONARBPROC)SDL_GL_GetProcAddress("glGetUniformLocationARB"); 249 glLinkProgramARB = (PFNGLLINKPROGRAMARBPROC)SDL_GL_GetProcAddress("glLinkProgramARB"); 250 glShaderSourceARB = (PFNGLSHADERSOURCEARBPROC)SDL_GL_GetProcAddress("glShaderSourceARB"); 251 glUniform1iARB = (PFNGLUNIFORM1IARBPROC)SDL_GL_GetProcAddress("glUniform1iARB"); 252 glUseProgramObjectARB = (PFNGLUSEPROGRAMOBJECTARBPROC)SDL_GL_GetProcAddress("glUseProgramObjectARB"); 253 if (glAttachObjectARB && 254 glCompileShaderARB && 255 glCreateProgramObjectARB && 256 glCreateShaderObjectARB && 257 glDeleteObjectARB && 258 glGetInfoLogARB && 259 glGetObjectParameterivARB && 260 glGetUniformLocationARB && 261 glLinkProgramARB && 262 glShaderSourceARB && 263 glUniform1iARB && 264 glUseProgramObjectARB) { 265 shaders_supported = SDL_TRUE; 266 } 267 } 268 269 if (!shaders_supported) { 270 return SDL_FALSE; 271 } 272 273 /* Compile all the shaders */ 274 for (i = 0; i < NUM_SHADERS; ++i) { 275 if (!CompileShaderProgram(&shaders[i])) { 276 SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Unable to compile shader!\n"); 277 return SDL_FALSE; 278 } 279 } 280 281 /* We're done! */ 282 return SDL_TRUE; 283 } 284 285 static void QuitShaders() 286 { 287 int i; 288 289 for (i = 0; i < NUM_SHADERS; ++i) { 290 DestroyShaderProgram(&shaders[i]); 291 } 292 } 293 294 /* Quick utility function for texture creation */ 295 static int 296 power_of_two(int input) 297 { 298 int value = 1; 299 300 while (value < input) { 301 value <<= 1; 302 } 303 return value; 304 } 305 306 GLuint 307 SDL_GL_LoadTexture(SDL_Surface *surface, GLfloat *texcoord) 308 { 309 GLuint texture; 310 int w, h; 311 SDL_Surface *image; 312 SDL_Rect area; 313 SDL_BlendMode saved_mode; 314 315 /* Use the surface width and height expanded to powers of 2 */ 316 w = power_of_two(surface->w); 317 h = power_of_two(surface->h); 318 texcoord[0] = 0.0f; /* Min X */ 319 texcoord[1] = 0.0f; /* Min Y */ 320 texcoord[2] = (GLfloat)surface->w / w; /* Max X */ 321 texcoord[3] = (GLfloat)surface->h / h; /* Max Y */ 322 323 image = SDL_CreateRGBSurface(SDL_SWSURFACE, w, h, 32, 324 #if SDL_BYTEORDER == SDL_LIL_ENDIAN /* OpenGL RGBA masks */ 325 0x000000FF, 326 0x0000FF00, 0x00FF0000, 0xFF000000 327 #else 328 0xFF000000, 329 0x00FF0000, 0x0000FF00, 0x000000FF 330 #endif 331 ); 332 if (image == NULL) { 333 return 0; 334 } 335 336 /* Save the alpha blending attributes */ 337 SDL_GetSurfaceBlendMode(surface, &saved_mode); 338 SDL_SetSurfaceBlendMode(surface, SDL_BLENDMODE_NONE); 339 340 /* Copy the surface into the GL texture image */ 341 area.x = 0; 342 area.y = 0; 343 area.w = surface->w; 344 area.h = surface->h; 345 SDL_BlitSurface(surface, &area, image, &area); 346 347 /* Restore the alpha blending attributes */ 348 SDL_SetSurfaceBlendMode(surface, saved_mode); 349 350 /* Create an OpenGL texture for the image */ 351 glGenTextures(1, &texture); 352 glBindTexture(GL_TEXTURE_2D, texture); 353 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); 354 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); 355 glTexImage2D(GL_TEXTURE_2D, 356 0, 357 GL_RGBA, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, image->pixels); 358 SDL_FreeSurface(image); /* No longer needed */ 359 360 return texture; 361 } 362 363 /* A general OpenGL initialization function. Sets all of the initial parameters. */ 364 void InitGL(int Width, int Height) /* We call this right after our OpenGL window is created. */ 365 { 366 GLdouble aspect; 367 368 glViewport(0, 0, Width, Height); 369 glClearColor(0.0f, 0.0f, 0.0f, 0.0f); /* This Will Clear The Background Color To Black */ 370 glClearDepth(1.0); /* Enables Clearing Of The Depth Buffer */ 371 glDepthFunc(GL_LESS); /* The Type Of Depth Test To Do */ 372 glEnable(GL_DEPTH_TEST); /* Enables Depth Testing */ 373 glShadeModel(GL_SMOOTH); /* Enables Smooth Color Shading */ 374 375 glMatrixMode(GL_PROJECTION); 376 glLoadIdentity(); /* Reset The Projection Matrix */ 377 378 aspect = (GLdouble)Width / Height; 379 glOrtho(-3.0, 3.0, -3.0 / aspect, 3.0 / aspect, 0.0, 1.0); 380 381 glMatrixMode(GL_MODELVIEW); 382 } 383 384 /* The main drawing function. */ 385 void DrawGLScene(SDL_Window *window, GLuint texture, GLfloat *texcoord) 386 { 387 /* Texture coordinate lookup, to make it simple */ 388 enum 389 { 390 MINX, 391 MINY, 392 MAXX, 393 MAXY 394 }; 395 396 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); /* Clear The Screen And The Depth Buffer */ 397 glLoadIdentity(); /* Reset The View */ 398 399 glTranslatef(-1.5f, 0.0f, 0.0f); /* Move Left 1.5 Units */ 400 401 /* draw a triangle (in smooth coloring mode) */ 402 glBegin(GL_POLYGON); /* start drawing a polygon */ 403 glColor3f(1.0f, 0.0f, 0.0f); /* Set The Color To Red */ 404 glVertex3f(0.0f, 1.0f, 0.0f); /* Top */ 405 glColor3f(0.0f, 1.0f, 0.0f); /* Set The Color To Green */ 406 glVertex3f(1.0f, -1.0f, 0.0f); /* Bottom Right */ 407 glColor3f(0.0f, 0.0f, 1.0f); /* Set The Color To Blue */ 408 glVertex3f(-1.0f, -1.0f, 0.0f); /* Bottom Left */ 409 glEnd(); /* we're done with the polygon (smooth color interpolation) */ 410 411 glTranslatef(3.0f, 0.0f, 0.0f); /* Move Right 3 Units */ 412 413 /* Enable blending */ 414 glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE); 415 glEnable(GL_BLEND); 416 glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); 417 418 /* draw a textured square (quadrilateral) */ 419 glEnable(GL_TEXTURE_2D); 420 glBindTexture(GL_TEXTURE_2D, texture); 421 glColor3f(1.0f, 1.0f, 1.0f); 422 if (shaders_supported) { 423 glUseProgramObjectARB(shaders[current_shader].program); 424 } 425 426 glBegin(GL_QUADS); /* start drawing a polygon (4 sided) */ 427 glTexCoord2f(texcoord[MINX], texcoord[MINY]); 428 glVertex3f(-1.0f, 1.0f, 0.0f); /* Top Left */ 429 glTexCoord2f(texcoord[MAXX], texcoord[MINY]); 430 glVertex3f(1.0f, 1.0f, 0.0f); /* Top Right */ 431 glTexCoord2f(texcoord[MAXX], texcoord[MAXY]); 432 glVertex3f(1.0f, -1.0f, 0.0f); /* Bottom Right */ 433 glTexCoord2f(texcoord[MINX], texcoord[MAXY]); 434 glVertex3f(-1.0f, -1.0f, 0.0f); /* Bottom Left */ 435 glEnd(); /* done with the polygon */ 436 437 if (shaders_supported) { 438 glUseProgramObjectARB(0); 439 } 440 glDisable(GL_TEXTURE_2D); 441 442 /* swap buffers to display, since we're double buffered. */ 443 SDL_GL_SwapWindow(window); 444 } 445 446 int main(int argc, char **argv) 447 { 448 int done; 449 SDL_Window *window; 450 SDL_Surface *surface; 451 GLuint texture; 452 GLfloat texcoords[4]; 453 454 /* Enable standard application logging */ 455 SDL_LogSetPriority(SDL_LOG_CATEGORY_APPLICATION, SDL_LOG_PRIORITY_INFO); 456 457 /* Initialize SDL for video output */ 458 if (SDL_Init(SDL_INIT_VIDEO) < 0) { 459 SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Unable to initialize SDL: %s\n", SDL_GetError()); 460 exit(1); 461 } 462 463 /* Create a 640x480 OpenGL screen */ 464 window = SDL_CreateWindow("Shader Demo", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 640, 480, SDL_WINDOW_OPENGL); 465 if (window == NULL) { 466 SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Unable to create OpenGL window: %s\n", SDL_GetError()); 467 SDL_Quit(); 468 exit(2); 469 } 470 471 if (!SDL_GL_CreateContext(window)) { 472 SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Unable to create OpenGL context: %s\n", SDL_GetError()); 473 SDL_Quit(); 474 exit(2); 475 } 476 477 surface = SDL_LoadBMP("icon.bmp"); 478 if (surface == NULL) { 479 SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Unable to load icon.bmp: %s\n", SDL_GetError()); 480 SDL_Quit(); 481 exit(3); 482 } 483 texture = SDL_GL_LoadTexture(surface, texcoords); 484 SDL_FreeSurface(surface); 485 486 /* Loop, drawing and checking events */ 487 InitGL(640, 480); 488 if (InitShaders()) { 489 SDL_Log("Shaders supported, press SPACE to cycle them.\n"); 490 } else { 491 SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Shaders not supported!\n"); 492 } 493 done = 0; 494 while (!done) { 495 DrawGLScene(window, texture, texcoords); 496 497 /* This could go in a separate function */ 498 { 499 SDL_Event event; 500 while (SDL_PollEvent(&event)) { 501 if (event.type == SDL_QUIT) { 502 done = 1; 503 } 504 if (event.type == SDL_KEYDOWN) { 505 if (event.key.keysym.sym == SDLK_SPACE) { 506 current_shader = (current_shader + 1) % NUM_SHADERS; 507 } 508 if (event.key.keysym.sym == SDLK_ESCAPE) { 509 done = 1; 510 } 511 } 512 } 513 } 514 } 515 QuitShaders(); 516 SDL_Quit(); 517 return 1; 518 } 519 520 #else /* HAVE_OPENGL */ 521 522 int main(int argc, char *argv[]) 523 { 524 SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "No OpenGL support on this system\n"); 525 return 1; 526 } 527 528 #endif /* HAVE_OPENGL */ 529 530 /* vi: set ts=4 sw=4 expandtab: */