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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_QUAD_STRIP;
GLubyte val;
int bits, max, i;
GLboolean failed;
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);
failed = GL_FALSE;
printf("Testing GL_INCR...\n");
for (i = 1; i < max+10; i++) {
int expected = (i > max) ? max : i;
glBegin(prim);
glVertex2f(0, 0); glVertex2f(10, 0);
glVertex2f(0, 10); glVertex2f(10, 10);
glEnd();
glReadPixels(0, 0, 1, 1, GL_STENCIL_INDEX, GL_UNSIGNED_BYTE, &val);
if (val != expected) {
printf( "Failed GL_INCR test on iteration #%u "
"(got %u, expected %u)\n", i, val, expected );
failed = GL_TRUE;
}
}
if ( !failed ) printf("OK!\n");
/* test GL_INCR_WRAP_EXT (wrap around) */
glClear(GL_STENCIL_BUFFER_BIT);
glStencilOp(GL_KEEP, GL_KEEP, GL_INCR_WRAP_EXT);
failed = GL_FALSE;
printf("Testing GL_INCR_WRAP_EXT...\n");
for (i = 1; i < max+10; i++) {
int expected = i % (max + 1);
glBegin(prim);
glVertex2f(0, 0); glVertex2f(10, 0);
glVertex2f(0, 10); glVertex2f(10, 10);
glEnd();
glReadPixels(0, 0, 1, 1, GL_STENCIL_INDEX, GL_UNSIGNED_BYTE, &val);
if (val != expected) {
printf( "Failed GL_INCR_WRAP test on iteration #%u "
"(got %u, expected %u)\n", i, val, expected );
failed = GL_TRUE;
}
}
if ( !failed ) printf("OK!\n");
glClearStencil(max);
/* test GL_INCR (saturation) */
glClear(GL_STENCIL_BUFFER_BIT);
glStencilOp(GL_KEEP, GL_KEEP, GL_DECR);
failed = GL_FALSE;
printf("Testing GL_DECR...\n");
for (i = max-1; i > -10; i--) {
int expected = (i < 0) ? 0 : i;
glBegin(prim);
glVertex2f(0, 0); glVertex2f(10, 0);
glVertex2f(0, 10); glVertex2f(10, 10);
glEnd();
glReadPixels(0, 0, 1, 1, GL_STENCIL_INDEX, GL_UNSIGNED_BYTE, &val);
if (val != expected) {
printf( "Failed GL_DECR test on iteration #%u "
"(got %u, expected %u)\n", max - i, val, expected );
failed = GL_TRUE;
}
}
if ( !failed ) printf("OK!\n");
/* test GL_INCR_WRAP_EXT (wrap-around) */
glClear(GL_STENCIL_BUFFER_BIT);
glStencilOp(GL_KEEP, GL_KEEP, GL_DECR_WRAP_EXT);
failed = GL_FALSE;
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, 0); glVertex2f(10, 0);
glVertex2f(0, 10); glVertex2f(10, 10);
glEnd();
glReadPixels(0, 0, 1, 1, GL_STENCIL_INDEX, GL_UNSIGNED_BYTE, &val);
if (val != expected) {
printf( "Failed GL_DECR_WRAP test on iteration #%u "
"(got %u, expected %u)\n", max - i, val, expected );
failed = GL_TRUE;
}
}
if ( !failed ) 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 )
{
const char * ver_str;
float version;
printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
printf("GL_VERSION = %s\n", (char *) glGetString(GL_VERSION));
/* Check for both the extension string and GL version 1.4 on the
* outside chance that some silly vendor exports version 1.4 but doesn't
* export the extension string. The stencil-wrap modes are a required
* part of GL 1.4.
*/
ver_str = glGetString( GL_VERSION );
version = (ver_str == NULL) ? 1.0 : atof( ver_str );
if ( !glutExtensionSupported("GL_EXT_stencil_wrap")
&& (version < 1.4) ) {
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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