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-rw-r--r--progs/tests/zreaddraw.c12
1 files changed, 12 insertions, 0 deletions
diff --git a/progs/tests/zreaddraw.c b/progs/tests/zreaddraw.c
index 8839e10836..0821d5fb35 100644
--- a/progs/tests/zreaddraw.c
+++ b/progs/tests/zreaddraw.c
@@ -12,6 +12,7 @@
#include <GL/glut.h>
static GLint WinWidth = 500, WinHeight = 500;
+static GLboolean Invert = GL_FALSE;
static void Display(void)
@@ -50,7 +51,15 @@ static void Display(void)
glPixelZoom(4.0, 4.0);
glColor4f(1, 0, 0, 0);
glWindowPos2i(100, 0);
+ if (Invert) {
+ glPixelTransferf(GL_DEPTH_SCALE, -1.0);
+ glPixelTransferf(GL_DEPTH_BIAS, 1.0);
+ }
glDrawPixels(100, 100, GL_DEPTH_COMPONENT, GL_FLOAT, depth);
+ if (Invert) {
+ glPixelTransferf(GL_DEPTH_SCALE, 1.0);
+ glPixelTransferf(GL_DEPTH_BIAS, 0.0);
+ }
glDisable(GL_DEPTH_TEST);
@@ -77,6 +86,9 @@ static void Key(unsigned char key, int x, int y)
(void) x;
(void) y;
switch (key) {
+ case 'i':
+ Invert = !Invert;
+ break;
case 27:
exit(0);
break;