progs/trivial/tex-quads.c

   1 /**
   2  * Draw a series of quads, each with a different texture.
   3  */
   4
   5 #include <stdio.h>
   6 #include <string.h>
   7 #include <stdlib.h>
   8 #include <GL/glew.h>
   9 #include <GL/glut.h>
  10
  11 #define NUM_TEX 10
  12
  13 static GLint Win = 0;
  14 static GLuint Tex[NUM_TEX];
  15
  16
  17 static void Init(void)
  18 {
  19    int i;
  20
  21    fprintf(stderr, "GL_RENDERER   = %s\n", (char *) glGetString(GL_RENDERER));
  22    fflush(stderr);
  23
  24    glGenTextures(NUM_TEX, Tex);
  25
  26    for (i = 0; i < NUM_TEX; i++) {
  27       glBindTexture(GL_TEXTURE_2D, Tex[i]);
  28
  29       glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
  30       glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
  31       glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
  32       glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
  33       glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
  34    }
  35 }
  36
  37
  38 static void Reshape(int width, int height)
  39 {
  40    float ar = (float) width / height;
  41    glViewport(0, 0, width, height);
  42    glMatrixMode(GL_PROJECTION);
  43    glLoadIdentity();
  44    glOrtho(-ar, ar, -1.0, 1.0, -1.0, 1.0);
  45    glMatrixMode(GL_MODELVIEW);
  46 }
  47
  48
  49 static void Key(unsigned char key, int x, int y)
  50 {
  51    if (key == 27) {
  52       glDeleteTextures(NUM_TEX, Tex);
  53       glutDestroyWindow(Win);
  54       exit(1);
  55    }
  56    glutPostRedisplay();
  57 }
  58
  59
  60 static void Draw(void)
  61 {
  62    GLubyte tex[16][16][4];
  63    int t, i, j;
  64
  65    for (t = 0; t < NUM_TEX; t++) {
  66
  67       for (i = 0; i < 16; i++) {
  68          for (j = 0; j < 16; j++) {
  69             if (i < t) {
  70                /* red row */
  71                tex[i][j][0] = 255;
  72                tex[i][j][1] = 0;
  73                tex[i][j][2] = 0;
  74                tex[i][j][3] = 255;
  75             }
  76             else if ((i + j) & 1) {
  77                tex[i][j][0] = 128;
  78                tex[i][j][1] = 128;
  79                tex[i][j][2] = 128;
  80                tex[i][j][3] = 255;
  81             }
  82             else {
  83                tex[i][j][0] = 255;
  84                tex[i][j][1] = 255;
  85                tex[i][j][2] = 255;
  86                tex[i][j][3] = 255;
  87             }
  88          }
  89       }
  90
  91       glBindTexture(GL_TEXTURE_2D, Tex[t]);
  92       glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 16, 16, 0,
  93                    GL_RGBA, GL_UNSIGNED_BYTE, tex);
  94    }
  95
  96    glEnable(GL_TEXTURE_2D);
  97
  98    glClear(GL_COLOR_BUFFER_BIT);
  99
 100    for (i = 0; i < NUM_TEX; i++) {
 101
 102       glBindTexture(GL_TEXTURE_2D, Tex[i]);
 103
 104       glPushMatrix();
 105       glTranslatef(-4.0 + i, 0, 0);
 106       glScalef(0.5, 0.5, 1.0);
 107
 108       glBegin(GL_QUADS);
 109       glTexCoord2f(1,0);
 110       glVertex3f( 0.9, -0.9, 0.0);
 111       glTexCoord2f(1,1);
 112       glVertex3f( 0.9,  0.9, 0.0);
 113       glTexCoord2f(0,1);
 114       glVertex3f(-0.9,  0.9, 0.0);
 115       glTexCoord2f(0,0);
 116       glVertex3f(-0.9,  -0.9, 0.0);
 117       glEnd();
 118
 119       glPopMatrix();
 120    }
 121
 122
 123    glutSwapBuffers();
 124 }
 125
 126
 127 int main(int argc, char **argv)
 128 {
 129    glutInit(&argc, argv);
 130    glutInitWindowSize(900, 200);
 131    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
 132    Win = glutCreateWindow(*argv);
 133    if (!Win) {
 134       exit(1);
 135    }
 136    glewInit();
 137    Init();
 138    glutReshapeFunc(Reshape);
 139    glutKeyboardFunc(Key);
 140    glutDisplayFunc(Draw);
 141    glutMainLoop();
 142    return 0;
 143 }