/***************************************************************************** * file: v11.c * status: 09-may-2001, pfk. * function: Example of texture mapping. ****************************************************************************/ #include #include #include /* Size and position of output window. */ #define WINSIZE_X 500 /* width in pixels */ #define WINSIZE_Y 500 /* height in pixels */ #define WINPOS_X 100 /* position of left */ #define WINPOS_Y 100 /* upper corner */ /* Array of unsigned bytes to hold texture image: * minimum image size is 64x64, * both sizes must be power of 2, not necessarily the same power. */ static int texImageWidth, texImageHeight; static GLubyte *texImage; /* ptr to 3-dimensional array: texImage[texImageWidth][texImageHeight][4] with four bytes per pixel */ /**************************************************************************** * Get texture image from pgm- or ppm-file. * Format of input file: * - line containing ascii file type, e.g. strings 'P5' or 'P6' * - optional ascii comment lines starting with '#' * - ascii line containing horizontal and vertical size separated by space * - ascii line containing number '255' * - binary pixel values: single byte per pixel with grayscale if type P5 (pgm) * - triples of bytes with RGB values if type P6 (ppm) ***************************************************************************/ void getImageFromFile (void) { #define inputLineLength 81 int i, j; int byteValue, intensityLevels; char inputLine[inputLineLength], typeOfFile[3]; FILE *f = fopen ("mickey.ppm", "r"); if (f == NULL) /* check if file exists */ { fprintf (stderr, "\nERROR: Failed to open file 'mickey.ppm'.\n"); exit (1); } /* Get file type. */ do fgets (inputLine, inputLineLength-1, f); while (inputLine[0] == '#'); typeOfFile[0] = inputLine[0]; typeOfFile[1] = inputLine[1]; typeOfFile[2] = '\0'; printf (" file type: %s\n", typeOfFile); /* Get horizontal en vertical size. */ do fgets (inputLine, inputLineLength-1, f); while (inputLine[0] == '#'); sscanf (inputLine, "%d %d", &texImageWidth, &texImageHeight); printf (" horizontal: %d\n", texImageWidth); printf (" vertical: %d\n", texImageHeight); /* Allocate array that will contain the texture image. */ texImage = (GLubyte *) malloc (texImageWidth*texImageHeight*4*sizeof(GLubyte)); /* Get number with maximum number of shades. */ do fgets (inputLine, inputLineLength-1, f); while (inputLine[0] == '#'); sscanf (inputLine, "%d", &intensityLevels); printf (" int levels: %d\n", intensityLevels); /* Copy binary pixel values into texture image array. */ for (i = texImageHeight-1; i >= 0; i--) { for (j = 0; j < texImageWidth; j++) { int position = (i*texImageWidth+j)*4; /* read and store RGB or grayscale values*/ byteValue = getc (f); /* R-value or grayscale value */ texImage[position] = (GLubyte) byteValue; if (typeOfFile[1] == '6') byteValue = getc (f); /* G-value if file type = R6 */ texImage[position+1] = (GLubyte) byteValue; if (typeOfFile[1] == '6') byteValue = getc (f); /* B-value if file type = R6 */ texImage[position+2] = (GLubyte) byteValue; /* alpha-value */ texImage[position+3] = (GLubyte) 255; } } } /**************************************************************************** * Create texture image and do set-up for texture mapping. ***************************************************************************/ void progInit (void) { glClearColor (0.8, 0.8, 0.0, 0.0); glShadeModel (GL_FLAT); /* flat shading */ glEnable (GL_DEPTH_TEST); /* use depth buffer */ getImageFromFile (); /* set pixel storage mode to byte alignment, since data * are stored in GLubyte texImage[][][] */ glPixelStorei (GL_UNPACK_ALIGNMENT, 1); /* 2D texture mapping */ /* set wrap parameter for coordinates s and t to repeat */ glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT); glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT); /* set texture minifying and magnification to choose texture element * nearest to center of pixel being textured */ glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); /* specify 2D texture image */ glTexImage2D (GL_TEXTURE_2D, 0, 4, texImageWidth, texImageHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, texImage); } /**************************************************************************** * Display textured objects: * three four-sided polygons with the same 2D texture applied (cube), * one four-sided polygon with part of the same 2D texture applied. ***************************************************************************/ void progDisplay (void) { glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); /* enable 2D texture mapping */ glEnable (GL_TEXTURE_2D); /* set texture environment variables */ glTexEnvf (GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL); glBegin (GL_QUADS); /* 2D texture image and corresponding object coordinate */ glTexCoord2f (0.0, 0.0); glVertex3f (-2.2, -1.0, 0.0); glTexCoord2f (0.0, 1.0); glVertex3f (-2.2, 1.0, 0.0); glTexCoord2f (1.0, 1.0); glVertex3f ( 1.0, 1.0, 0.0); glTexCoord2f (1.0, 0.0); glVertex3f ( 1.0, -1.0, 0.0); glTexCoord2f (0.0, 0.0); glVertex3f ( 1.0, -1.0, 0.0); glTexCoord2f (0.0, 1.0); glVertex3f ( 1.0, 1.0, 0.0); glTexCoord2f (1.0, 1.0); glVertex3f ( 2.4, 1.8, -1.4); glTexCoord2f (1.0, 0.0); glVertex3f ( 2.4, -0.2, -1.4); glTexCoord2f (0.0, 0.0); glVertex3f (-2.2, 1.0, 0.0); glTexCoord2f (0.0, 1.0); glVertex3f (-0.8, 1.8, -1.4); glTexCoord2f (1.0, 1.0); glVertex3f ( 2.4, 1.8, -1.4); glTexCoord2f (1.0, 0.0); glVertex3f ( 1.0, 1.0, 0.0); glTexCoord2f (0.5, 0.4); glVertex3f (-1.0, 1.8, 0.0); glTexCoord2f (0.5, 0.9); glVertex3f (-1.0, 2.6, 0.0); glTexCoord2f (1.0, 0.9); glVertex3f ( 0.3, 2.6, 0.0); glTexCoord2f (1.0, 0.4); glVertex3f ( 0.3, 1.8, 0.0); glEnd (); /* disable 2D texture mapping */ glDisable (GL_TEXTURE_2D); glFlush (); } /**************************************************************************** * Reshape handling. ***************************************************************************/ void progReshape (int w, int h) { glViewport (0, 0, (GLsizei) w, (GLsizei) h); glMatrixMode (GL_PROJECTION); glLoadIdentity (); gluPerspective (60.0, (GLfloat) w/(GLfloat) h, 1.0, 10.0); glMatrixMode (GL_MODELVIEW); glLoadIdentity (); glTranslatef ( 0.3, -0.8, -3.6); } /**************************************************************************** * Keyboard handling. ***************************************************************************/ void progKeyboard (unsigned char key, int x, int y) { switch (key) { case 'q': exit(0); break; case 27: exit(0); break; default: break; } } /**************************************************************************** * Main program. ***************************************************************************/ int main (int argc, char** argv) { glutInit (&argc, argv); glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH); glutInitWindowSize (WINSIZE_X, WINSIZE_Y); glutInitWindowPosition (WINPOS_X, WINPOS_Y); glutCreateWindow (argv[0]); progInit (); glutDisplayFunc (progDisplay); glutReshapeFunc (progReshape); glutKeyboardFunc (progKeyboard); glutMainLoop (); return 0; }