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/* Test GL_EXT_stencil_wrap extension.
* This is by no means complete, just a quick check.
*
* Brian Paul 30 October 2002
*/
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <GL/glut.h>
static void RunTest(void)
{
const GLenum prim = GL_LINES;
GLubyte val;
int bits, max, i;
glGetIntegerv(GL_STENCIL_BITS, &bits);
max = (1 << bits) - 1;
glClearStencil(0);
glEnable(GL_STENCIL_TEST);
glStencilFunc(GL_ALWAYS, 0, ~0);
/* test GL_INCR (saturation) */
glClear(GL_STENCIL_BUFFER_BIT);
glStencilOp(GL_KEEP, GL_KEEP, GL_INCR);
printf("Testing GL_INCR...\n");
for (i = 1; i < max+10; i++) {
int expected = (i > max) ? max : i;
glBegin(prim);
glVertex2f(0.5, 0.5); glVertex2f(9.5, 0.5);
glEnd();
glReadPixels(0, 0, 1, 1, GL_STENCIL_INDEX, GL_UNSIGNED_BYTE, &val);
assert(val == expected);
}
printf("OK!\n");
/* test GL_INCR_WRAP_EXT (wrap around) */
glClear(GL_STENCIL_BUFFER_BIT);
glStencilOp(GL_KEEP, GL_KEEP, GL_INCR_WRAP_EXT);
printf("Testing GL_INCR_WRAP_EXT...\n");
for (i = 1; i < max+10; i++) {
int expected = i % (max + 1);
glBegin(prim);
glVertex2f(0.5, 0.5); glVertex2f(9.5, 0.5);
glEnd();
glReadPixels(0, 0, 1, 1, GL_STENCIL_INDEX, GL_UNSIGNED_BYTE, &val);
assert(val == expected);
}
printf("OK!\n");
glClearStencil(max);
/* test GL_INCR (saturation) */
glClear(GL_STENCIL_BUFFER_BIT);
glStencilOp(GL_KEEP, GL_KEEP, GL_DECR);
printf("Testing GL_DECR...\n");
for (i = max-1; i > -10; i--) {
int expected = (i < 0) ? 0 : i;
glBegin(prim);
glVertex2f(0.5, 0.5); glVertex2f(9.5, 0.5);
glEnd();
glReadPixels(0, 0, 1, 1, GL_STENCIL_INDEX, GL_UNSIGNED_BYTE, &val);
assert(val == expected);
}
printf("OK!\n");
/* test GL_INCR_WRAP_EXT (wrap-around) */
glClear(GL_STENCIL_BUFFER_BIT);
glStencilOp(GL_KEEP, GL_KEEP, GL_DECR_WRAP_EXT);
printf("Testing GL_DECR_WRAP_EXT...\n");
for (i = max-1; i > -10; i--) {
int expected = (i < 0) ? max + i + 1: i;
glBegin(prim);
glVertex2f(0.5, 0.5); glVertex2f(9.5, 0.5);
glEnd();
glReadPixels(0, 0, 1, 1, GL_STENCIL_INDEX, GL_UNSIGNED_BYTE, &val);
assert(val == expected);
}
printf("OK!\n");
glDisable(GL_STENCIL_TEST);
}
static void Display( void )
{
glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
RunTest();
glutSwapBuffers();
}
static void Reshape( int width, int height )
{
glViewport( 0, 0, width, height );
glMatrixMode( GL_PROJECTION );
glLoadIdentity();
glOrtho(0, width, 0, height, -1, 1);
glMatrixMode( GL_MODELVIEW );
glLoadIdentity();
}
static void Key( unsigned char key, int x, int y )
{
(void) x;
(void) y;
switch (key) {
case 27:
exit(0);
break;
}
glutPostRedisplay();
}
static void Init( void )
{
printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
printf("GL_VERSION = %s\n", (char *) glGetString(GL_VERSION));
if (!glutExtensionSupported("GL_EXT_stencil_wrap")) {
printf("Sorry, GL_EXT_stencil_wrap not supported.\n");
exit(1);
}
}
int main( int argc, char *argv[] )
{
glutInit( &argc, argv );
glutInitWindowPosition( 0, 0 );
glutInitWindowSize( 400, 400 );
glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE | GLUT_STENCIL );
glutCreateWindow(argv[0]);
glutReshapeFunc( Reshape );
glutKeyboardFunc( Key );
glutDisplayFunc( Display );
Init();
glutMainLoop();
return 0;
}
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