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_QUAD_STRIP;
  17    GLubyte val;
  18    int bits, max, i;
  19    GLboolean failed;
  20
  21    glGetIntegerv(GL_STENCIL_BITS, &bits);
  22    max = (1 << bits) - 1;
  23
  24    glClearStencil(0);
  25    glEnable(GL_STENCIL_TEST);
  26    glStencilFunc(GL_ALWAYS, 0, ~0);
  27
  28    /* test GL_INCR (saturation) */
  29    glClear(GL_STENCIL_BUFFER_BIT);
  30    glStencilOp(GL_KEEP, GL_KEEP, GL_INCR);
  31    failed = GL_FALSE;
  32    printf("Testing GL_INCR...\n");
  33    for (i = 1; i < max+10; i++) {
  34       int expected = (i > max) ? max : i;
  35       glBegin(prim);
  36       glVertex2f(0, 0);      glVertex2f(10, 0);
  37       glVertex2f(0, 10);      glVertex2f(10, 10);
  38       glEnd();
  39
  40       glReadPixels(0, 0, 1, 1, GL_STENCIL_INDEX, GL_UNSIGNED_BYTE, &val);
  41       if (val != expected) {
  42          printf( "Failed GL_INCR test on iteration #%u "
  43                  "(got %u, expected %u)\n", i, val, expected );
  44          failed = GL_TRUE;
  45       }
  46    }
  47
  48    if ( !failed ) printf("OK!\n");
  49
  50
  51    /* test GL_INCR_WRAP_EXT (wrap around) */
  52    glClear(GL_STENCIL_BUFFER_BIT);
  53    glStencilOp(GL_KEEP, GL_KEEP, GL_INCR_WRAP_EXT);
  54    failed = GL_FALSE;
  55    printf("Testing GL_INCR_WRAP_EXT...\n");
  56    for (i = 1; i < max+10; i++) {
  57       int expected = i % (max + 1);
  58       glBegin(prim);
  59       glVertex2f(0, 0);      glVertex2f(10, 0);
  60       glVertex2f(0, 10);      glVertex2f(10, 10);
  61       glEnd();
  62       glReadPixels(0, 0, 1, 1, GL_STENCIL_INDEX, GL_UNSIGNED_BYTE, &val);
  63       if (val != expected) {
  64          printf( "Failed GL_INCR_WRAP test on iteration #%u "
  65                  "(got %u, expected %u)\n", i, val, expected );
  66          failed = GL_TRUE;
  67       }
  68    }
  69    if ( !failed ) printf("OK!\n");
  70
  71    glClearStencil(max);
  72
  73    /* test GL_INCR (saturation) */
  74    glClear(GL_STENCIL_BUFFER_BIT);
  75    glStencilOp(GL_KEEP, GL_KEEP, GL_DECR);
  76    failed = GL_FALSE;
  77    printf("Testing GL_DECR...\n");
  78    for (i = max-1; i > -10; i--) {
  79       int expected = (i < 0) ? 0 : i;
  80       glBegin(prim);
  81       glVertex2f(0, 0);      glVertex2f(10, 0);
  82       glVertex2f(0, 10);      glVertex2f(10, 10);
  83       glEnd();
  84       glReadPixels(0, 0, 1, 1, GL_STENCIL_INDEX, GL_UNSIGNED_BYTE, &val);
  85       if (val != expected) {
  86          printf( "Failed GL_DECR test on iteration #%u "
  87                  "(got %u, expected %u)\n", max - i, val, expected );
  88          failed = GL_TRUE;
  89       }
  90    }
  91    if ( !failed ) printf("OK!\n");
  92
  93    /* test GL_INCR_WRAP_EXT (wrap-around) */
  94    glClear(GL_STENCIL_BUFFER_BIT);
  95    glStencilOp(GL_KEEP, GL_KEEP, GL_DECR_WRAP_EXT);
  96    failed = GL_FALSE;
  97    printf("Testing GL_DECR_WRAP_EXT...\n");
  98    for (i = max-1; i > -10; i--) {
  99       int expected = (i < 0) ? max + i + 1: i;
 100       glBegin(prim);
 101       glVertex2f(0, 0);      glVertex2f(10, 0);
 102       glVertex2f(0, 10);      glVertex2f(10, 10);
 103       glEnd();
 104       glReadPixels(0, 0, 1, 1, GL_STENCIL_INDEX, GL_UNSIGNED_BYTE, &val);
 105       if (val != expected) {
 106          printf( "Failed GL_DECR_WRAP test on iteration #%u "
 107                  "(got %u, expected %u)\n", max - i, val, expected );
 108          failed = GL_TRUE;
 109       }
 110    }
 111    if ( !failed ) printf("OK!\n");
 112
 113    glDisable(GL_STENCIL_TEST);
 114 }
 115
 116
 117 static void Display( void )
 118 {
 119    glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
 120
 121    RunTest();
 122
 123    glutSwapBuffers();
 124 }
 125
 126
 127 static void Reshape( int width, int height )
 128 {
 129    glViewport( 0, 0, width, height );
 130    glMatrixMode( GL_PROJECTION );
 131    glLoadIdentity();
 132    glOrtho(0, width, 0, height, -1, 1);
 133    glMatrixMode( GL_MODELVIEW );
 134    glLoadIdentity();
 135 }
 136
 137
 138 static void Key( unsigned char key, int x, int y )
 139 {
 140    (void) x;
 141    (void) y;
 142    switch (key) {
 143       case 27:
 144          exit(0);
 145          break;
 146    }
 147    glutPostRedisplay();
 148 }
 149
 150
 151 static void Init( void )
 152 {
 153    const char * ver_str;
 154    float        version;
 155
 156    printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
 157    printf("GL_VERSION = %s\n", (char *) glGetString(GL_VERSION));
 158
 159
 160    /* Check for both the extension string and GL version 1.4 on the
 161     * outside chance that some silly vendor exports version 1.4 but doesn't
 162     * export the extension string.  The stencil-wrap modes are a required
 163     * part of GL 1.4.
 164     */
 165
 166    ver_str = glGetString( GL_VERSION );
 167    version = (ver_str == NULL) ? 1.0 : strtof( ver_str, NULL );
 168
 169    if ( !glutExtensionSupported("GL_EXT_stencil_wrap")
 170         && (version < 1.4) ) {
 171       printf("Sorry, GL_EXT_stencil_wrap not supported.\n");
 172       exit(1);
 173    }
 174 }
 175
 176
 177 int main( int argc, char *argv[] )
 178 {
 179    glutInit( &argc, argv );
 180    glutInitWindowPosition( 0, 0 );
 181    glutInitWindowSize( 400, 400 );
 182    glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE | GLUT_STENCIL );
 183    glutCreateWindow(argv[0]);
 184    glutReshapeFunc( Reshape );
 185    glutKeyboardFunc( Key );
 186    glutDisplayFunc( Display );
 187    Init();
 188    glutMainLoop();
 189    return 0;
 190 }