It's not available in OpenGL ES and officially it's not supported on OpenGL 3.0/3.1.
Fallback to old depth range code if there is no method to disable depth clipping.
It's more important to have correct clipping than to have accurate depth values.
Inaccurate depth values can be fixed by slow depth.
In TimeSplitters: Future Perfect, PerfQuery is used to detect
the visibility of lights and draw coronas. 25 points are drawn
for each light. However, the returned count was incorrectly
being divided by four leading to dim coronas.
Using 4x antialiasing was a workaround because of a bug where
antialiasing multiplied the PerfQuery results. This commit
fixes that bug too (but only for OpenGL).
Note: It's not 100% perfect, as some of the GPU capablities leak into the
pixel shader UID.
Currently our UIDs don't get exported, so there is no issue. But someone
might want to fix this in the future.
As much as possible, the asserts have been moved out of the GetUID
function. But there are some places where asserts depend on variables
that aren't stored in the shader UID.
Jules Blok
Lioncash
hthh
degasus
Scott Mansell
Pierre Bourdon