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    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(0.5, 0.5);      glVertex2f(9.5, 0.5);
  37       glEnd();
  38
  39       glReadPixels(0, 0, 1, 1, GL_STENCIL_INDEX, GL_UNSIGNED_BYTE, &val);
  40       if (val != expected) {
  41          printf( "Failed GL_INCR test on iteration #%u "
  42                  "(got %u, expected %u)\n", i, val, expected );
  43          failed = GL_TRUE;
  44       }
  45    }
  46
  47    if ( !failed ) printf("OK!\n");
  48
  49
  50    /* test GL_INCR_WRAP_EXT (wrap around) */
  51    glClear(GL_STENCIL_BUFFER_BIT);
  52    glStencilOp(GL_KEEP, GL_KEEP, GL_INCR_WRAP_EXT);
  53    failed = GL_FALSE;
  54    printf("Testing GL_INCR_WRAP_EXT...\n");
  55    for (i = 1; i < max+10; i++) {
  56       int expected = i % (max + 1);
  57       glBegin(prim);
  58       glVertex2f(0.5, 0.5);      glVertex2f(9.5, 0.5);
  59       glEnd();
  60       glReadPixels(0, 0, 1, 1, GL_STENCIL_INDEX, GL_UNSIGNED_BYTE, &val);
  61       if (val != expected) {
  62          printf( "Failed GL_INCR_WRAP test on iteration #%u "
  63                  "(got %u, expected %u)\n", i, val, expected );
  64          failed = GL_TRUE;
  65       }
  66    }
  67    if ( !failed ) printf("OK!\n");
  68
  69    glClearStencil(max);
  70
  71    /* test GL_INCR (saturation) */
  72    glClear(GL_STENCIL_BUFFER_BIT);
  73    glStencilOp(GL_KEEP, GL_KEEP, GL_DECR);
  74    failed = GL_FALSE;
  75    printf("Testing GL_DECR...\n");
  76    for (i = max-1; i > -10; i--) {
  77       int expected = (i < 0) ? 0 : i;
  78       glBegin(prim);
  79       glVertex2f(0.5, 0.5);      glVertex2f(9.5, 0.5);
  80       glEnd();
  81       glReadPixels(0, 0, 1, 1, GL_STENCIL_INDEX, GL_UNSIGNED_BYTE, &val);
  82       if (val != expected) {
  83          printf( "Failed GL_DECR test on iteration #%u "
  84                  "(got %u, expected %u)\n", max - i, val, expected );
  85          failed = GL_TRUE;
  86       }
  87    }
  88    if ( !failed ) printf("OK!\n");
  89
  90    /* test GL_INCR_WRAP_EXT (wrap-around) */
  91    glClear(GL_STENCIL_BUFFER_BIT);
  92    glStencilOp(GL_KEEP, GL_KEEP, GL_DECR_WRAP_EXT);
  93    failed = GL_FALSE;
  94    printf("Testing GL_DECR_WRAP_EXT...\n");
  95    for (i = max-1; i > -10; i--) {
  96       int expected = (i < 0) ? max + i + 1: i;
  97       glBegin(prim);
  98       glVertex2f(0.5, 0.5);      glVertex2f(9.5, 0.5);
  99       glEnd();
 100       glReadPixels(0, 0, 1, 1, GL_STENCIL_INDEX, GL_UNSIGNED_BYTE, &val);
 101       if (val != expected) {
 102          printf( "Failed GL_DECR_WRAP test on iteration #%u "
 103                  "(got %u, expected %u)\n", max - i, val, expected );
 104          failed = GL_TRUE;
 105       }
 106    }
 107    if ( !failed ) printf("OK!\n");
 108
 109    glDisable(GL_STENCIL_TEST);
 110 }
 111
 112
 113 static void Display( void )
 114 {
 115    glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
 116
 117    RunTest();
 118
 119    glutSwapBuffers();
 120 }
 121
 122
 123 static void Reshape( int width, int height )
 124 {
 125    glViewport( 0, 0, width, height );
 126    glMatrixMode( GL_PROJECTION );
 127    glLoadIdentity();
 128    glOrtho(0, width, 0, height, -1, 1);
 129    glMatrixMode( GL_MODELVIEW );
 130    glLoadIdentity();
 131 }
 132
 133
 134 static void Key( unsigned char key, int x, int y )
 135 {
 136    (void) x;
 137    (void) y;
 138    switch (key) {
 139       case 27:
 140          exit(0);
 141          break;
 142    }
 143    glutPostRedisplay();
 144 }
 145
 146
 147 static void Init( void )
 148 {
 149    const char * ver_str;
 150    float        version;
 151
 152    printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
 153    printf("GL_VERSION = %s\n", (char *) glGetString(GL_VERSION));
 154
 155
 156    /* Check for both the extension string and GL version 1.4 on the
 157     * outside chance that some silly vendor exports version 1.4 but doesn't
 158     * export the extension string.  The stencil-wrap modes are a required
 159     * part of GL 1.4.
 160     */
 161
 162    ver_str = glGetString( GL_VERSION );
 163    version = (ver_str == NULL) ? 1.0 : strtof( ver_str, NULL );
 164
 165    if ( !glutExtensionSupported("GL_EXT_stencil_wrap")
 166         && (version < 1.4) ) {
 167       printf("Sorry, GL_EXT_stencil_wrap not supported.\n");
 168       exit(1);
 169    }
 170 }
 171
 172
 173 int main( int argc, char *argv[] )
 174 {
 175    glutInit( &argc, argv );
 176    glutInitWindowPosition( 0, 0 );
 177    glutInitWindowSize( 400, 400 );
 178    glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE | GLUT_STENCIL );
 179    glutCreateWindow(argv[0]);
 180    glutReshapeFunc( Reshape );
 181    glutKeyboardFunc( Key );
 182    glutDisplayFunc( Display );
 183    Init();
 184    glutMainLoop();
 185    return 0;
 186 }