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Diffstat (limited to 'progs/trivial/quad-offset-factor.c')
-rw-r--r--progs/trivial/quad-offset-factor.c23
1 files changed, 6 insertions, 17 deletions
diff --git a/progs/trivial/quad-offset-factor.c b/progs/trivial/quad-offset-factor.c
index 861d3461c0..90943d908f 100644
--- a/progs/trivial/quad-offset-factor.c
+++ b/progs/trivial/quad-offset-factor.c
@@ -27,11 +27,6 @@
#include <stdlib.h>
#include <GL/glut.h>
-
-#define CI_OFFSET_1 16
-#define CI_OFFSET_2 32
-
-
GLenum doubleBuffer;
static void Init(void)
@@ -45,7 +40,6 @@ static void Init(void)
static void Reshape(int width, int height)
{
-
glViewport(0, 0, (GLint)width, (GLint)height);
glMatrixMode(GL_PROJECTION);
@@ -56,7 +50,6 @@ static void Reshape(int width, int height)
static void Key(unsigned char key, int x, int y)
{
-
switch (key) {
case 27:
exit(1);
@@ -75,7 +68,6 @@ static void quad( float half )
glVertex3f(-half/9.0, half/9.0, -25.0 - half);
glVertex3f(-half/9.0, -half/9.0, -25.0 - half);
glEnd();
-
}
static void Draw(void)
@@ -83,27 +75,24 @@ static void Draw(void)
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glEnable(GL_DEPTH_TEST);
-
-
+ /* red: offset back */
glEnable(GL_POLYGON_OFFSET_FILL);
glPolygonOffset(1, 0);
-
glColor3f(1,0,0);
quad(9);
+ /* green: no offset */
glDisable(GL_POLYGON_OFFSET_FILL);
glColor3f(0,1,0);
quad(6);
-
+ /* black: offset zero, should not be visible because of z test */
glEnable(GL_POLYGON_OFFSET_FILL);
glPolygonOffset(0, 0);
-
- /* Black - should not be visible
- */
glColor3f(0,0,0);
quad(6);
+ /* blue: offset forward */
glEnable(GL_POLYGON_OFFSET_FILL);
glPolygonOffset(-1, 0);
glColor3f(0,0,1);
@@ -149,7 +138,7 @@ int main(int argc, char **argv)
glutInitWindowPosition(0, 0); glutInitWindowSize( 250, 250);
- type = GLUT_RGB | GLUT_DEPTH;
+ type = GLUT_RGB | GLUT_ALPHA | GLUT_DEPTH;
type |= (doubleBuffer) ? GLUT_DOUBLE : GLUT_SINGLE;
glutInitDisplayMode(type);
@@ -163,5 +152,5 @@ int main(int argc, char **argv)
glutKeyboardFunc(Key);
glutDisplayFunc(Draw);
glutMainLoop();
- return 0;
+ return 0;
}