View Full Version : Overlapping 32bit transparent images.

10-10-2006, 12:32 AM
Hi All,

I am trying to draw 2 transparent bitmaps (with alpha channel) on a gradient background.

When I draw the first using glDrawPixels I got the perfect result: transparent pixels leave the gradient background pass through.

When I draw the second one it correcty blend with the background but not with the first bitmap.

Is it a known limitation or am I missing something?

Thanks a lot,


10-10-2006, 01:30 AM
Pictures speak a thousand words. A screen shot would be very useful.

10-10-2006, 03:25 AM
glDrawPixels uses the z-value of the last glRasterPos call to generate depth informations. Make sure you have depth test disabled.

10-10-2006, 03:46 AM
Yes, yes, yes, Relic. Disabling GL_DEPTH_TEST solved the problem.

As an italian, I owe a pizza!

Thanks again,