progs/tests/stencilwrap.c

   1 /* Test GL_EXT_stencil_wrap extension.
   2  * This is by no means complete, just a quick check.
   3  *
   4  * Brian Paul  30 October 2002
   5  */
   6
   7 #include <assert.h>
   8 #include <stdio.h>
   9 #include <stdlib.h>
  10 #include <math.h>
  11 #include <GL/glut.h>
  12
  13
  14 static void RunTest(void)
  15 {
  16    const GLenum prim = GL_LINES;
  17    GLubyte val;
  18    int bits, max, i;
  19
  20    glGetIntegerv(GL_STENCIL_BITS, &bits);
  21    max = (1 << bits) - 1;
  22
  23    glClearStencil(0);
  24    glEnable(GL_STENCIL_TEST);
  25    glStencilFunc(GL_ALWAYS, 0, ~0);
  26
  27    /* test GL_INCR (saturation) */
  28    glClear(GL_STENCIL_BUFFER_BIT);
  29    glStencilOp(GL_KEEP, GL_KEEP, GL_INCR);
  30    printf("Testing GL_INCR...\n");
  31    for (i = 1; i < max+10; i++) {
  32       int expected = (i > max) ? max : i;
  33       glBegin(prim);
  34       glVertex2f(0.5, 0.5);      glVertex2f(9.5, 0.5);
  35       glEnd();
  36       glReadPixels(0, 0, 1, 1, GL_STENCIL_INDEX, GL_UNSIGNED_BYTE, &val);
  37       assert(val == expected);
  38    }
  39    printf("OK!\n");
  40
  41    /* test GL_INCR_WRAP_EXT (wrap around) */
  42    glClear(GL_STENCIL_BUFFER_BIT);
  43    glStencilOp(GL_KEEP, GL_KEEP, GL_INCR_WRAP_EXT);
  44    printf("Testing GL_INCR_WRAP_EXT...\n");
  45    for (i = 1; i < max+10; i++) {
  46       int expected = i % (max + 1);
  47       glBegin(prim);
  48       glVertex2f(0.5, 0.5);      glVertex2f(9.5, 0.5);
  49       glEnd();
  50       glReadPixels(0, 0, 1, 1, GL_STENCIL_INDEX, GL_UNSIGNED_BYTE, &val);
  51       assert(val == expected);
  52    }
  53    printf("OK!\n");
  54
  55    glClearStencil(max);
  56
  57    /* test GL_INCR (saturation) */
  58    glClear(GL_STENCIL_BUFFER_BIT);
  59    glStencilOp(GL_KEEP, GL_KEEP, GL_DECR);
  60    printf("Testing GL_DECR...\n");
  61    for (i = max-1; i > -10; i--) {
  62       int expected = (i < 0) ? 0 : i;
  63       glBegin(prim);
  64       glVertex2f(0.5, 0.5);      glVertex2f(9.5, 0.5);
  65       glEnd();
  66       glReadPixels(0, 0, 1, 1, GL_STENCIL_INDEX, GL_UNSIGNED_BYTE, &val);
  67       assert(val == expected);
  68    }
  69    printf("OK!\n");
  70
  71    /* test GL_INCR_WRAP_EXT (wrap-around) */
  72    glClear(GL_STENCIL_BUFFER_BIT);
  73    glStencilOp(GL_KEEP, GL_KEEP, GL_DECR_WRAP_EXT);
  74    printf("Testing GL_DECR_WRAP_EXT...\n");
  75    for (i = max-1; i > -10; i--) {
  76       int expected = (i < 0) ? max + i + 1: i;
  77       glBegin(prim);
  78       glVertex2f(0.5, 0.5);      glVertex2f(9.5, 0.5);
  79       glEnd();
  80       glReadPixels(0, 0, 1, 1, GL_STENCIL_INDEX, GL_UNSIGNED_BYTE, &val);
  81       assert(val == expected);
  82    }
  83    printf("OK!\n");
  84
  85    glDisable(GL_STENCIL_TEST);
  86 }
  87
  88
  89 static void Display( void )
  90 {
  91    glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
  92
  93    RunTest();
  94
  95    glutSwapBuffers();
  96 }
  97
  98
  99 static void Reshape( int width, int height )
 100 {
 101    glViewport( 0, 0, width, height );
 102    glMatrixMode( GL_PROJECTION );
 103    glLoadIdentity();
 104    glOrtho(0, width, 0, height, -1, 1);
 105    glMatrixMode( GL_MODELVIEW );
 106    glLoadIdentity();
 107 }
 108
 109
 110 static void Key( unsigned char key, int x, int y )
 111 {
 112    (void) x;
 113    (void) y;
 114    switch (key) {
 115       case 27:
 116          exit(0);
 117          break;
 118    }
 119    glutPostRedisplay();
 120 }
 121
 122
 123 static void Init( void )
 124 {
 125    printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
 126    printf("GL_VERSION = %s\n", (char *) glGetString(GL_VERSION));
 127    if (!glutExtensionSupported("GL_EXT_stencil_wrap")) {
 128       printf("Sorry, GL_EXT_stencil_wrap not supported.\n");
 129       exit(1);
 130    }
 131 }
 132
 133
 134 int main( int argc, char *argv[] )
 135 {
 136    glutInit( &argc, argv );
 137    glutInitWindowPosition( 0, 0 );
 138    glutInitWindowSize( 400, 400 );
 139    glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE | GLUT_STENCIL );
 140    glutCreateWindow(argv[0]);
 141    glutReshapeFunc( Reshape );
 142    glutKeyboardFunc( Key );
 143    glutDisplayFunc( Display );
 144    Init();
 145    glutMainLoop();
 146    return 0;
 147 }