progs/tests/seccolor.c

   1 /*
   2  * Exercise GL_EXT_secondary_color
   3  */
   4
   5
   6 #define GL_GLEXT_PROTOTYPES
   7 #include <stdio.h>
   8 #include <stdlib.h>
   9 #include <math.h>
  10 #include <GL/glut.h>
  11
  12 static int Width = 600;
  13 static int Height = 200;
  14 static GLfloat Near = 5.0, Far = 25.0;
  15
  16
  17 static void Display( void )
  18 {
  19    GLfloat t;
  20
  21    glClearColor(0.2, 0.2, 0.8, 0);
  22    glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
  23
  24    for (t = 0.0; t <= 1.0; t += 0.25) {
  25       GLfloat x =  t * 10.0 - 5.0;
  26       GLfloat g = t;
  27
  28       /* top row: untextured */
  29       glColor3f(1, 0, 0);
  30       glPushMatrix();
  31          glTranslatef(x, 1.2, 0);
  32 #if defined(GL_EXT_secondary_color)
  33          glSecondaryColor3fEXT(0, g, 0);
  34 #endif
  35          glBegin(GL_POLYGON);
  36          glVertex2f(-1, -1);
  37          glVertex2f( 1, -1);
  38          glVertex2f( 1,  1);
  39          glVertex2f(-1,  1);
  40          glEnd();
  41       glPopMatrix();
  42
  43       /* bottom row: textured */
  44       glColor3f(1, 1, 1);
  45       glEnable(GL_TEXTURE_2D);
  46       glPushMatrix();
  47          glTranslatef(x, -1.2, 0);
  48 #if defined(GL_EXT_secondary_color)
  49          glSecondaryColor3fEXT(0, g, 0);
  50 #endif
  51          glBegin(GL_POLYGON);
  52          glTexCoord2f(0, 0);  glVertex2f(-1, -1);
  53          glTexCoord2f(1, 0);  glVertex2f( 1, -1);
  54          glTexCoord2f(1, 1);  glVertex2f( 1,  1);
  55          glTexCoord2f(0, 1);  glVertex2f(-1,  1);
  56          glEnd();
  57       glPopMatrix();
  58       glDisable(GL_TEXTURE_2D);
  59    }
  60    glutSwapBuffers();
  61 }
  62
  63
  64 static void Reshape( int width, int height )
  65 {
  66    GLfloat ar = (float) width / (float) height;
  67    Width = width;
  68    Height = height;
  69    glViewport( 0, 0, width, height );
  70    glMatrixMode( GL_PROJECTION );
  71    glLoadIdentity();
  72    glFrustum( -ar, ar, -1.0, 1.0, Near, Far );
  73    glMatrixMode( GL_MODELVIEW );
  74    glLoadIdentity();
  75    glTranslatef( 0.0, 0.0, -15.0 );
  76 }
  77
  78
  79 static void Key( unsigned char key, int x, int y )
  80 {
  81    (void) x;
  82    (void) y;
  83    switch (key) {
  84       case 27:
  85          exit(0);
  86          break;
  87    }
  88    glutPostRedisplay();
  89 }
  90
  91
  92 static void Init( void )
  93 {
  94    GLubyte image[4*4][3];
  95    GLint i;
  96    if (!glutExtensionSupported("GL_EXT_secondary_color")) {
  97       printf("Sorry, this program requires GL_EXT_secondary_color\n");
  98       exit(1);
  99    }
 100
 101    /* setup red texture with one back texel */
 102    for (i = 0; i < 4*4; i++) {
 103       if (i == 0) {
 104          image[i][0] = 0;
 105          image[i][1] = 0;
 106          image[i][2] = 0;
 107       }
 108       else {
 109          image[i][0] = 255;
 110          image[i][1] = 0;
 111          image[i][2] = 0;
 112       }
 113    }
 114    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, 4, 4, 0,
 115                 GL_RGB, GL_UNSIGNED_BYTE, image);
 116    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
 117    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
 118    glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
 119
 120 #if defined(GL_EXT_secondary_color)
 121    glEnable(GL_COLOR_SUM_EXT);
 122 #endif
 123    glLightModeli(GL_LIGHT_MODEL_COLOR_CONTROL, GL_SEPARATE_SPECULAR_COLOR);
 124
 125    printf("Squares should be colored from red -> orange -> yellow.\n");
 126    printf("Top row is untextured.\n");
 127    printf("Bottom row is textured (red texture with one black texel).\n");
 128    printf("Rows should be identical, except for lower-left texel.\n");
 129 }
 130
 131
 132 int main( int argc, char *argv[] )
 133 {
 134    glutInit( &argc, argv );
 135    glutInitWindowPosition( 0, 0 );
 136    glutInitWindowSize( Width, Height );
 137    glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE );
 138    glutCreateWindow(argv[0]);
 139    glutReshapeFunc( Reshape );
 140    glutKeyboardFunc( Key );
 141    glutDisplayFunc( Display );
 142    Init();
 143    glutMainLoop();
 144    return 0;
 145 }