![]() |
|Download Files|
![]() ![]() ![]() ![]() ![]() Next: 4.1.4 Stencil test Up: 4.1 Per-Fragment Operations Previous: 4.1.2 Scissor test
4.1.3 Alpha testThis step applies only in RGBA mode. In color index mode, proceed to the next step. The alpha test discards a fragment conditional on the outcome of a comparison between the incoming fragment's alpha value and a constant value. The comparison is enabled or disabled with the generic Enable and Disable commands using the symbolic constant ALPHA_TEST. When disabled, it is as if the comparison always passes. The test is controlled with
void AlphaFunc ( enum func, clampf ref ) ;
func is a symbolic constant indicating
the alpha test function; ref is a reference value.
ref is clamped to lie in The required state consists of the floating-point reference value, an eight-valued integer indicating the comparison function, and a bit indicating if the comparison is enabled or disabled. The initial state is for the reference value to be 0 and the function to be ALWAYS. Initially, the alpha test is disabled.
David Blythe Sat Mar 29 02:23:21 PST 1997
|