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-rw-r--r--progs/trivial/tri-z-eq.c14
1 files changed, 11 insertions, 3 deletions
diff --git a/progs/trivial/tri-z-eq.c b/progs/trivial/tri-z-eq.c
index b81c992f7d..195e8a26f6 100644
--- a/progs/trivial/tri-z-eq.c
+++ b/progs/trivial/tri-z-eq.c
@@ -69,6 +69,8 @@ static void Key(unsigned char key, int x, int y)
static void Draw(void)
{
+ float z = 1.0;
+
glClearColor(0.0, 0.0, 1.0, 0.0);
glClearDepth(1.0);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
@@ -77,15 +79,21 @@ static void Draw(void)
glBegin(GL_TRIANGLES);
glColor3f(0,0,.7);
- glVertex3f( 0.9, -0.9, 1.0);
+ glVertex3f( 0.9, -0.9, z);
glColor3f(.8,0,0);
- glVertex3f( 0.9, 0.9, 1.0);
+ glVertex3f( 0.9, 0.9, z);
glColor3f(0,.9,0);
- glVertex3f(-0.9, 0.0, 1.0);
+ glVertex3f(-0.9, 0.0, z);
glEnd();
glFlush();
+ {
+ GLfloat z;
+ glReadPixels(125, 125, 1, 1, GL_DEPTH_COMPONENT, GL_FLOAT, &z);
+ printf("Z at (125, 125) = %f\n", z);
+ }
+
if (doubleBuffer) {
glutSwapBuffers();
}