I sometimes disable depth buffer writing via glDepthMask(GL_FALSE) during the alpha rendering of a frame. That works perfectly fine on some GPUs (like the Motorola Droid's PowerVR), but on the HTC EVO ...
I am doing a GL multi-pass rendering app for iOS. The first pass renders to a depth buffer texture. The second pass uses the values in the depth buffer to control the application of a fragment shader. ...
Shadow mapping uses the depth buffer to calculate where shadows should be drawn. My problem is that I'd like some semi transparent textured quads to cast shadows - for example billboarded trees. As ...