View Full Version : excuse me OpenGL gurus

11-07-2001, 12:55 AM
if you look at the specification of glClear()
function, then there is a statement which reads exactly like this ---

"Alpha function, blend function, logical operation, stenciling, texture mapping, and depth buffering are ignored by glClear."

What is the meaning of this statement.??
Can it be verified ? How??

11-07-2001, 01:10 AM
An example. If you enable alpha test, you can reject fragments based on it's alpha value. Say you decide to reject fragments with alpha less than 0.5. Now, if you set the clear color to (1, 1, 1, 0.1), the alpha value of the clear color will be 0.1 which is less than 0.5. So, one can ask him/herself, will all fragments generated by glClear be rejected becasue of the alpha function? No it won't, becuse the specifications says that the alpha function is ignored.

Same thing for the other stuff.