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Tutorials MySQL & C, C++ How to do Texture Mapping in OpenGL?? – A sample example. - tutorial advance
Tutorials MySQL & C, C++ How to do Texture Mapping in OpenGL?? – A sample example. - tutorial advance
How to do Texture Mapping in OpenGL?? – A sample example.
destination source:https://www.programming-techniques.com/2012/01/how-to-do-texture-mapping-in-opengl-a-sample-example.html
Texture mapping is the process of applying colors from an image to an object created in OpenGL. A simple example would be, applying a brick image onto a square which makes the square look like an original wall.
OpenGL supports four basic texture map types. 1D, 2D, 3D and cube map textures. The following code is an example of a 2D texture mapping, which provides a basic usage of textures.
Note: To run this code on your machine, make a bitmap image (64 x 64) and name it floor.bmp . Keep this image in the same folder where your exe file is located. If you are Code::Blocks user, then compiling from IDE results in Error, it says that it couldn’t found the Image. So just compile it and run the exe file which is inside debug or release folder. Visual Studio user can directly run this program without even including <windows.h> but Code::Blocks user must include <windows.h>.
Source Code:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 | #include <windows.h> //for Code::Blocks user #include <GL/glut.h> #include <stdio.h> #include <gl\gl.h> #include <gl\glu.h> #include <stdlib.h> GLuint texture[2]; struct Image { unsigned long sizeX; unsigned long sizeY; char *data; }; typedef struct Image Image; #define checkImageWidth 64 #define checkImageHeight 64 GLubyte checkImage[checkImageWidth][checkImageHeight][3]; void makeCheckImage(void){ int i, j, c; for (i = 0; i < checkImageWidth; i++) { for (j = 0; j < checkImageHeight; j++) { c = ((((i&0x8)==0)^((j&0x8)==0)))*255; checkImage[i][j][0] = (GLubyte) c; checkImage[i][j][1] = (GLubyte) c; checkImage[i][j][2] = (GLubyte) c; } } } int ImageLoad(char *filename, Image *image) { FILE *file; unsigned long size; // size of the image in bytes. unsigned long i; // standard counter. unsigned short int planes; // number of planes in image (must be 1) unsigned short int bpp; // number of bits per pixel (must be 24) char temp; // temporary color storage for bgr-rgb conversion. // make sure the file is there. if ((file = fopen(filename, "rb"))==NULL){ printf("File Not Found : %s\n",filename); return 0; } // seek through the bmp header, up to the width/height: fseek(file, 18, SEEK_CUR); // read the width if ((i = fread(&image->sizeX, 4, 1, file)) != 1) { printf("Error reading width from %s.\n", filename); return 0; } //printf("Width of %s: %lu\n", filename, image->sizeX); // read the height if ((i = fread(&image->sizeY, 4, 1, file)) != 1) { printf("Error reading height from %s.\n", filename); return 0; } //printf("Height of %s: %lu\n", filename, image->sizeY); // calculate the size (assuming 24 bits or 3 bytes per pixel). size = image->sizeX * image->sizeY * 3; // read the planes if ((fread(&planes, 2, 1, file)) != 1) { printf("Error reading planes from %s.\n", filename); return 0; } if (planes != 1) { printf("Planes from %s is not 1: %u\n", filename, planes); return 0; } // read the bitsperpixel if ((i = fread(&bpp, 2, 1, file)) != 1) { printf("Error reading bpp from %s.\n", filename); return 0; } if (bpp != 24) { printf("Bpp from %s is not 24: %u\n", filename, bpp); return 0; } // seek past the rest of the bitmap header. fseek(file, 24, SEEK_CUR); // read the data. image->data = (char *) malloc(size); if (image->data == NULL) { printf("Error allocating memory for color-corrected image data"); return 0; } if ((i = fread(image->data, size, 1, file)) != 1) { printf("Error reading image data from %s.\n", filename); return 0; } for (i=0;i<size;i+=3) { // reverse all of the colors. (bgr -> rgb) temp = image->data[i]; image->data[i] = image->data[i+2]; image->data[i+2] = temp; } // we're done. return 1; } Image * loadTexture(){ Image *image1; // allocate space for texture image1 = (Image *) malloc(sizeof(Image)); if (image1 == NULL) { printf("Error allocating space for image"); exit(0); } if (!ImageLoad("floor.bmp", image1)) { exit(1); } return image1; } void myinit(void) { glClearColor (0.5, 0.5, 0.5, 0.0); glEnable(GL_DEPTH_TEST); glDepthFunc(GL_LESS); Image *image1 = loadTexture(); if(image1 == NULL){ printf("Image was not returned from loadTexture\n"); exit(0); } makeCheckImage(); glPixelStorei(GL_UNPACK_ALIGNMENT, 1); // Create Texture glGenTextures(2, texture); glBindTexture(GL_TEXTURE_2D, texture[0]); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR); //scale linearly when image bigger than texture glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR); //scale linearly when image smalled than texture glTexImage2D(GL_TEXTURE_2D, 0, 3, image1->sizeX, image1->sizeY, 0, GL_RGB, GL_UNSIGNED_BYTE, image1->data); glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL); glBindTexture(GL_TEXTURE_2D, texture[1]); glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP); glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP); glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL); glTexImage2D(GL_TEXTURE_2D, 0, 3, checkImageWidth, checkImageHeight, 0, GL_RGB, GL_UNSIGNED_BYTE,&checkImage[0][0][0]); glEnable(GL_TEXTURE_2D); glShadeModel(GL_FLAT); } void display(void){ glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glBindTexture(GL_TEXTURE_2D, texture[1]); glutSolidTeapot(1.0); glBindTexture(GL_TEXTURE_2D, texture[0]); glBegin(GL_QUADS); glTexCoord2f(0.0, 0.0); glVertex3f(1.0, -1.0, 0.0); glTexCoord2f(1.0, 0.0); glVertex3f(1.0, 1.0, 0.0); glTexCoord2f(1.0, 1.0); glVertex3f(2.41421, 1.0, -1.41421); glTexCoord2f(0.0, 1.0); glVertex3f(2.41421, -1.0, -1.41421); glEnd(); glutSwapBuffers(); } void myReshape(int w, int h){ glViewport(0, 0, w, h); glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluPerspective(60.0, 1.0*(GLfloat)w/(GLfloat)h, 1.0, 30.0); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glTranslatef(0.0, 0.0, -3.6); } void keyboard (unsigned char key, int x, int y){ switch (key) { case 27: // “esc” on keyboard exit(0); break; default: // “a” on keyboard break; } } int main(int argc, char** argv) { glutInit(&argc, argv); glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH); glutCreateWindow("Texture Mapping - Programming Techniques"); myinit(); glutReshapeFunc (myReshape); glutDisplayFunc(display); glutKeyboardFunc(keyboard); glutMainLoop(); return 0; } |
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