SDL2: test/testshader.c

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Member "SDL2-2.0.22/test/testshader.c" (9 Apr 2022, 16719 Bytes) of package /linux/misc/SDL2-2.0.22.tar.gz:

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2.0.20_vs_2.0.22.

1 /* 2 Copyright (C) 1997-2022 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 21 static SDL_bool shaders_supported; 22 static int current_shader = 0; 23 24 enum { 25 SHADER_COLOR, 26 SHADER_TEXTURE, 27 SHADER_TEXCOORDS, 28 NUM_SHADERS 29 }; 30 31 typedef struct { 32 GLhandleARB program; 33 GLhandleARB vert_shader; 34 GLhandleARB frag_shader; 35 const char *vert_source; 36 const char *frag_source; 37 } ShaderData; 38 39 static ShaderData shaders[NUM_SHADERS] = { 40 41 /* SHADER_COLOR */ 42 { 0, 0, 0, 43 /* vertex shader */ 44 "varying vec4 v_color;\n" 45 "\n" 46 "void main()\n" 47 "{\n" 48 " gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;\n" 49 " v_color = gl_Color;\n" 50 "}", 51 /* fragment shader */ 52 "varying vec4 v_color;\n" 53 "\n" 54 "void main()\n" 55 "{\n" 56 " gl_FragColor = v_color;\n" 57 "}" 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 83 /* SHADER_TEXCOORDS */ 84 { 0, 0, 0, 85 /* vertex shader */ 86 "varying vec2 v_texCoord;\n" 87 "\n" 88 "void main()\n" 89 "{\n" 90 " gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;\n" 91 " v_texCoord = vec2(gl_MultiTexCoord0);\n" 92 "}", 93 /* fragment shader */ 94 "varying vec2 v_texCoord;\n" 95 "\n" 96 "void main()\n" 97 "{\n" 98 " vec4 color;\n" 99 " vec2 delta;\n" 100 " float dist;\n" 101 "\n" 102 " delta = vec2(0.5, 0.5) - v_texCoord;\n" 103 " dist = dot(delta, delta);\n" 104 "\n" 105 " color.r = v_texCoord.x;\n" 106 " color.g = v_texCoord.x * v_texCoord.y;\n" 107 " color.b = v_texCoord.y;\n" 108 " color.a = 1.0 - (dist * 4.0);\n" 109 " gl_FragColor = color;\n" 110 "}" 111 }, 112 }; 113 114 static PFNGLATTACHOBJECTARBPROC glAttachObjectARB; 115 static PFNGLCOMPILESHADERARBPROC glCompileShaderARB; 116 static PFNGLCREATEPROGRAMOBJECTARBPROC glCreateProgramObjectARB; 117 static PFNGLCREATESHADEROBJECTARBPROC glCreateShaderObjectARB; 118 static PFNGLDELETEOBJECTARBPROC glDeleteObjectARB; 119 static PFNGLGETINFOLOGARBPROC glGetInfoLogARB; 120 static PFNGLGETOBJECTPARAMETERIVARBPROC glGetObjectParameterivARB; 121 static PFNGLGETUNIFORMLOCATIONARBPROC glGetUniformLocationARB; 122 static PFNGLLINKPROGRAMARBPROC glLinkProgramARB; 123 static PFNGLSHADERSOURCEARBPROC glShaderSourceARB; 124 static PFNGLUNIFORM1IARBPROC glUniform1iARB; 125 static PFNGLUSEPROGRAMOBJECTARBPROC glUseProgramObjectARB; 126 127 static SDL_bool CompileShader(GLhandleARB shader, const char *source) 128 { 129 GLint status = 0; 130 131 glShaderSourceARB(shader, 1, &source, NULL); 132 glCompileShaderARB(shader); 133 glGetObjectParameterivARB(shader, GL_OBJECT_COMPILE_STATUS_ARB, &status); 134 if (status == 0) { 135 GLint length = 0; 136 char *info; 137 138 glGetObjectParameterivARB(shader, GL_OBJECT_INFO_LOG_LENGTH_ARB, &length); 139 info = (char *) SDL_malloc(length + 1); 140 if (!info) { 141 SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Out of memory!"); 142 } else { 143 glGetInfoLogARB(shader, length, NULL, info); 144 SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Failed to compile shader:\n%s\n%s", source, info); 145 SDL_free(info); 146 } 147 return SDL_FALSE; 148 } else { 149 return SDL_TRUE; 150 } 151 } 152 153 static SDL_bool LinkProgram(ShaderData *data) 154 { 155 GLint status = 0; 156 157 glAttachObjectARB(data->program, data->vert_shader); 158 glAttachObjectARB(data->program, data->frag_shader); 159 glLinkProgramARB(data->program); 160 161 glGetObjectParameterivARB(data->program, GL_OBJECT_LINK_STATUS_ARB, &status); 162 if (status == 0) { 163 GLint length = 0; 164 char *info; 165 166 glGetObjectParameterivARB(data->program, GL_OBJECT_INFO_LOG_LENGTH_ARB, &length); 167 info = (char *) SDL_malloc(length + 1); 168 if (!info) { 169 SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Out of memory!"); 170 } else { 171 glGetInfoLogARB(data->program, length, NULL, info); 172 SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Failed to link program:\n%s", info); 173 SDL_free(info); 174 } 175 return SDL_FALSE; 176 } else { 177 return SDL_TRUE; 178 } 179 } 180 181 static SDL_bool CompileShaderProgram(ShaderData *data) 182 { 183 const int num_tmus_bound = 4; 184 int i; 185 GLint location; 186 187 glGetError(); 188 189 /* Create one program object to rule them all */ 190 data->program = glCreateProgramObjectARB(); 191 192 /* Create the vertex shader */ 193 data->vert_shader = glCreateShaderObjectARB(GL_VERTEX_SHADER_ARB); 194 if (!CompileShader(data->vert_shader, data->vert_source)) { 195 return SDL_FALSE; 196 } 197 198 /* Create the fragment shader */ 199 data->frag_shader = glCreateShaderObjectARB(GL_FRAGMENT_SHADER_ARB); 200 if (!CompileShader(data->frag_shader, data->frag_source)) { 201 return SDL_FALSE; 202 } 203 204 /* ... and in the darkness bind them */ 205 if (!LinkProgram(data)) { 206 return SDL_FALSE; 207 } 208 209 /* Set up some uniform variables */ 210 glUseProgramObjectARB(data->program); 211 for (i = 0; i < num_tmus_bound; ++i) { 212 char tex_name[5]; 213 SDL_snprintf(tex_name, SDL_arraysize(tex_name), "tex%d", i); 214 location = glGetUniformLocationARB(data->program, tex_name); 215 if (location >= 0) { 216 glUniform1iARB(location, i); 217 } 218 } 219 glUseProgramObjectARB(0); 220 221 return (glGetError() == GL_NO_ERROR) ? SDL_TRUE : SDL_FALSE; 222 } 223 224 static void DestroyShaderProgram(ShaderData *data) 225 { 226 if (shaders_supported) { 227 glDeleteObjectARB(data->vert_shader); 228 glDeleteObjectARB(data->frag_shader); 229 glDeleteObjectARB(data->program); 230 } 231 } 232 233 static SDL_bool InitShaders() 234 { 235 int i; 236 237 /* Check for shader support */ 238 shaders_supported = SDL_FALSE; 239 if (SDL_GL_ExtensionSupported("GL_ARB_shader_objects") && 240 SDL_GL_ExtensionSupported("GL_ARB_shading_language_100") && 241 SDL_GL_ExtensionSupported("GL_ARB_vertex_shader") && 242 SDL_GL_ExtensionSupported("GL_ARB_fragment_shader")) { 243 glAttachObjectARB = (PFNGLATTACHOBJECTARBPROC) SDL_GL_GetProcAddress("glAttachObjectARB"); 244 glCompileShaderARB = (PFNGLCOMPILESHADERARBPROC) SDL_GL_GetProcAddress("glCompileShaderARB"); 245 glCreateProgramObjectARB = (PFNGLCREATEPROGRAMOBJECTARBPROC) SDL_GL_GetProcAddress("glCreateProgramObjectARB"); 246 glCreateShaderObjectARB = (PFNGLCREATESHADEROBJECTARBPROC) SDL_GL_GetProcAddress("glCreateShaderObjectARB"); 247 glDeleteObjectARB = (PFNGLDELETEOBJECTARBPROC) SDL_GL_GetProcAddress("glDeleteObjectARB"); 248 glGetInfoLogARB = (PFNGLGETINFOLOGARBPROC) SDL_GL_GetProcAddress("glGetInfoLogARB"); 249 glGetObjectParameterivARB = (PFNGLGETOBJECTPARAMETERIVARBPROC) SDL_GL_GetProcAddress("glGetObjectParameterivARB"); 250 glGetUniformLocationARB = (PFNGLGETUNIFORMLOCATIONARBPROC) SDL_GL_GetProcAddress("glGetUniformLocationARB"); 251 glLinkProgramARB = (PFNGLLINKPROGRAMARBPROC) SDL_GL_GetProcAddress("glLinkProgramARB"); 252 glShaderSourceARB = (PFNGLSHADERSOURCEARBPROC) SDL_GL_GetProcAddress("glShaderSourceARB"); 253 glUniform1iARB = (PFNGLUNIFORM1IARBPROC) SDL_GL_GetProcAddress("glUniform1iARB"); 254 glUseProgramObjectARB = (PFNGLUSEPROGRAMOBJECTARBPROC) SDL_GL_GetProcAddress("glUseProgramObjectARB"); 255 if (glAttachObjectARB && 256 glCompileShaderARB && 257 glCreateProgramObjectARB && 258 glCreateShaderObjectARB && 259 glDeleteObjectARB && 260 glGetInfoLogARB && 261 glGetObjectParameterivARB && 262 glGetUniformLocationARB && 263 glLinkProgramARB && 264 glShaderSourceARB && 265 glUniform1iARB && 266 glUseProgramObjectARB) { 267 shaders_supported = SDL_TRUE; 268 } 269 } 270 271 if (!shaders_supported) { 272 return SDL_FALSE; 273 } 274 275 /* Compile all the shaders */ 276 for (i = 0; i < NUM_SHADERS; ++i) { 277 if (!CompileShaderProgram(&shaders[i])) { 278 SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Unable to compile shader!\n"); 279 return SDL_FALSE; 280 } 281 } 282 283 /* We're done! */ 284 return SDL_TRUE; 285 } 286 287 static void QuitShaders() 288 { 289 int i; 290 291 for (i = 0; i < NUM_SHADERS; ++i) { 292 DestroyShaderProgram(&shaders[i]); 293 } 294 } 295 296 /* Quick utility function for texture creation */ 297 static int 298 power_of_two(int input) 299 { 300 int value = 1; 301 302 while (value < input) { 303 value <<= 1; 304 } 305 return value; 306 } 307 308 GLuint 309 SDL_GL_LoadTexture(SDL_Surface * surface, GLfloat * texcoord) 310 { 311 GLuint texture; 312 int w, h; 313 SDL_Surface *image; 314 SDL_Rect area; 315 SDL_BlendMode saved_mode; 316 317 /* Use the surface width and height expanded to powers of 2 */ 318 w = power_of_two(surface->w); 319 h = power_of_two(surface->h); 320 texcoord[0] = 0.0f; /* Min X */ 321 texcoord[1] = 0.0f; /* Min Y */ 322 texcoord[2] = (GLfloat) surface->w / w; /* Max X */ 323 texcoord[3] = (GLfloat) surface->h / h; /* Max Y */ 324 325 image = SDL_CreateRGBSurface(SDL_SWSURFACE, w, h, 32, 326 #if SDL_BYTEORDER == SDL_LIL_ENDIAN /* OpenGL RGBA masks */ 327 0x000000FF, 328 0x0000FF00, 0x00FF0000, 0xFF000000 329 #else 330 0xFF000000, 331 0x00FF0000, 0x0000FF00, 0x000000FF 332 #endif 333 ); 334 if (image == NULL) { 335 return 0; 336 } 337 338 /* Save the alpha blending attributes */ 339 SDL_GetSurfaceBlendMode(surface, &saved_mode); 340 SDL_SetSurfaceBlendMode(surface, SDL_BLENDMODE_NONE); 341 342 /* Copy the surface into the GL texture image */ 343 area.x = 0; 344 area.y = 0; 345 area.w = surface->w; 346 area.h = surface->h; 347 SDL_BlitSurface(surface, &area, image, &area); 348 349 /* Restore the alpha blending attributes */ 350 SDL_SetSurfaceBlendMode(surface, saved_mode); 351 352 /* Create an OpenGL texture for the image */ 353 glGenTextures(1, &texture); 354 glBindTexture(GL_TEXTURE_2D, texture); 355 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); 356 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); 357 glTexImage2D(GL_TEXTURE_2D, 358 0, 359 GL_RGBA, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, image->pixels); 360 SDL_FreeSurface(image); /* No longer needed */ 361 362 return texture; 363 } 364 365 /* A general OpenGL initialization function. Sets all of the initial parameters. */ 366 void InitGL(int Width, int Height) /* We call this right after our OpenGL window is created. */ 367 { 368 GLdouble aspect; 369 370 glViewport(0, 0, Width, Height); 371 glClearColor(0.0f, 0.0f, 0.0f, 0.0f); /* This Will Clear The Background Color To Black */ 372 glClearDepth(1.0); /* Enables Clearing Of The Depth Buffer */ 373 glDepthFunc(GL_LESS); /* The Type Of Depth Test To Do */ 374 glEnable(GL_DEPTH_TEST); /* Enables Depth Testing */ 375 glShadeModel(GL_SMOOTH); /* Enables Smooth Color Shading */ 376 377 glMatrixMode(GL_PROJECTION); 378 glLoadIdentity(); /* Reset The Projection Matrix */ 379 380 aspect = (GLdouble)Width / Height; 381 glOrtho(-3.0, 3.0, -3.0 / aspect, 3.0 / aspect, 0.0, 1.0); 382 383 glMatrixMode(GL_MODELVIEW); 384 } 385 386 /* The main drawing function. */ 387 void DrawGLScene(SDL_Window *window, GLuint texture, GLfloat * texcoord) 388 { 389 /* Texture coordinate lookup, to make it simple */ 390 enum { 391 MINX, 392 MINY, 393 MAXX, 394 MAXY 395 }; 396 397 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); /* Clear The Screen And The Depth Buffer */ 398 glLoadIdentity(); /* Reset The View */ 399 400 glTranslatef(-1.5f,0.0f,0.0f); /* Move Left 1.5 Units */ 401 402 /* draw a triangle (in smooth coloring mode) */ 403 glBegin(GL_POLYGON); /* start drawing a polygon */ 404 glColor3f(1.0f,0.0f,0.0f); /* Set The Color To Red */ 405 glVertex3f( 0.0f, 1.0f, 0.0f); /* Top */ 406 glColor3f(0.0f,1.0f,0.0f); /* Set The Color To Green */ 407 glVertex3f( 1.0f,-1.0f, 0.0f); /* Bottom Right */ 408 glColor3f(0.0f,0.0f,1.0f); /* Set The Color To Blue */ 409 glVertex3f(-1.0f,-1.0f, 0.0f); /* Bottom Left */ 410 glEnd(); /* we're done with the polygon (smooth color interpolation) */ 411 412 glTranslatef(3.0f,0.0f,0.0f); /* Move Right 3 Units */ 413 414 /* Enable blending */ 415 glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE); 416 glEnable(GL_BLEND); 417 glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); 418 419 /* draw a textured square (quadrilateral) */ 420 glEnable(GL_TEXTURE_2D); 421 glBindTexture(GL_TEXTURE_2D, texture); 422 glColor3f(1.0f,1.0f,1.0f); 423 if (shaders_supported) { 424 glUseProgramObjectARB(shaders[current_shader].program); 425 } 426 427 glBegin(GL_QUADS); /* start drawing a polygon (4 sided) */ 428 glTexCoord2f(texcoord[MINX], texcoord[MINY]); 429 glVertex3f(-1.0f, 1.0f, 0.0f); /* Top Left */ 430 glTexCoord2f(texcoord[MAXX], texcoord[MINY]); 431 glVertex3f( 1.0f, 1.0f, 0.0f); /* Top Right */ 432 glTexCoord2f(texcoord[MAXX], texcoord[MAXY]); 433 glVertex3f( 1.0f,-1.0f, 0.0f); /* Bottom Right */ 434 glTexCoord2f(texcoord[MINX], texcoord[MAXY]); 435 glVertex3f(-1.0f,-1.0f, 0.0f); /* Bottom Left */ 436 glEnd(); /* done with the polygon */ 437 438 if (shaders_supported) { 439 glUseProgramObjectARB(0); 440 } 441 glDisable(GL_TEXTURE_2D); 442 443 /* swap buffers to display, since we're double buffered. */ 444 SDL_GL_SwapWindow(window); 445 } 446 447 int main(int argc, char **argv) 448 { 449 int done; 450 SDL_Window *window; 451 SDL_Surface *surface; 452 GLuint texture; 453 GLfloat texcoords[4]; 454 455 /* Enable standard application logging */ 456 SDL_LogSetPriority(SDL_LOG_CATEGORY_APPLICATION, SDL_LOG_PRIORITY_INFO); 457 458 /* Initialize SDL for video output */ 459 if ( SDL_Init(SDL_INIT_VIDEO) < 0 ) { 460 SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Unable to initialize SDL: %s\n", SDL_GetError()); 461 exit(1); 462 } 463 464 /* Create a 640x480 OpenGL screen */ 465 window = SDL_CreateWindow( "Shader Demo", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 640, 480, SDL_WINDOW_OPENGL ); 466 if ( !window ) { 467 SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Unable to create OpenGL window: %s\n", SDL_GetError()); 468 SDL_Quit(); 469 exit(2); 470 } 471 472 if ( !SDL_GL_CreateContext(window)) { 473 SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Unable to create OpenGL context: %s\n", SDL_GetError()); 474 SDL_Quit(); 475 exit(2); 476 } 477 478 surface = SDL_LoadBMP("icon.bmp"); 479 if ( ! surface ) { 480 SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Unable to load icon.bmp: %s\n", SDL_GetError()); 481 SDL_Quit(); 482 exit(3); 483 } 484 texture = SDL_GL_LoadTexture(surface, texcoords); 485 SDL_FreeSurface(surface); 486 487 /* Loop, drawing and checking events */ 488 InitGL(640, 480); 489 if (InitShaders()) { 490 SDL_Log("Shaders supported, press SPACE to cycle them.\n"); 491 } else { 492 SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Shaders not supported!\n"); 493 } 494 done = 0; 495 while ( ! done ) { 496 DrawGLScene(window, texture, texcoords); 497 498 /* This could go in a separate function */ 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 523 main(int argc, char *argv[]) 524 { 525 SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "No OpenGL support on this system\n"); 526 return 1; 527 } 528 529 #endif /* HAVE_OPENGL */ 530 531 /* vi: set ts=4 sw=4 expandtab: */