HP Workstation zx2000 HP OpenGL Implementation Guide for HP-UX 11.X (IPF versi - Page 14

overview of OpenGL 3D texture program fragments This program draws four layers in the base MIPmap level, and a diagonal slice through the base MIPmap level. /* Allocate texture levels separately, then concat to get 3D texture */ GLubyte texture1[TEXTURE_WIDTH][TEXTURE_HEIGHT][4]; GLubyte texture2[TEXTURE_WIDTH][TEXTURE_HEIGHT][4]; GLubyte texture3[TEXTURE_WIDTH][TEXTURE_HEIGHT][4]; GLubyte texture4[TEXTURE_WIDTH][TEXTURE_HEIGHT][4]; GLubyte textureConcat[TEXTURE_DEPTH][TEXTURE_WIDTH][TEXTURE_HEIGHT][4]; /* The checkerPattern procedure fills a texture of width and height with a period of Checker_period alternating between firstColor and secondColor, Texture should be declared prior to calling checkerPattern. */ static void checkerPattern(int width, int height, GLubyte *firstColor, GLubyte *secondColor, GLubyte *texture, int Checker_period) { int int GLubyte texelX, texelY; index, fromIndex; *p = texture; index = 0; for (texelY = 0; texelY < height; texelY++) { for (texelX = 0; texelX < width; texelX++) { if (((texelX/Checker_period)% 2) ^ ((texelY/Checker_period)% 2)) { *p++ = firstColor[0]; /* red */ *p++ = firstColor[1]; /* green */ *p++ = firstColor[2]; /* blue */ *p++ = firstColor[3]; /* alpha */ } else { *p++ = secondColor[0]; /* red */ *p++ = secondColor[1]; /* green */ *p++ = secondColor[2]; /* blue */ *p++ = secondColor[3]; /* alpha */ } } } GLubyte blackRGBA[] = {0.0, 0.0, 0.0, 255.0}; GLubyte whiteRGBA[] = {255.0, 255.0, 255.0, 255.0}; GLubyte redRGBA[] = {255.0, 0.0, 0.0, 255.0}; GLubyte greenRGBA[] = {0.0, 255.0, 0.0, 255.0}; GLubyte blueRGBA[] = {0.0, 0.0, 255.0, 255.0}; GLubyte yellowRGBA[]= {255.0, 255.0, 0.0, 255.0}; 1-10 OpenGL implementation guide