The fog settings do not depend on wether the shader writes to oFog or not,
instead they depend on the FOGVERTEXMODE and FOGTABLEMODE settings, and if a
vertex shader is bound at all.
It works the same way as with the fixed function, and having a vertex shader
is the same as using pretransformed vertices, just that the fog coord comes
from the shader instead of the specular color:
FOGTABLEMODE != NONE: The Z coord is used, oFog is ignored
FOGTABLEMODE == NONE, with VS: oFog is used
FOGTABLEMODE == NONE, no VS, XYZ: Z is used
FOGTABLEMODE == NONE, no VS, XYZRHW: diffuse color is used
This allows us to drop the load time conversion and the clear
readback hack and replaces it with a color fixup in the fixed
function pipeline replacement.
Based on a patch by Stefan Dösinger. This is more flexible, and allows
the shader backend implementation to be simpler, since it doesn't have
to know about specific formats. The next patch makes use of this.
GL_ATI_envmap_bumpmap provides two things: Signed V8U8 pixel formats,
and bump mapping. The extension is only supported on fglrx, and this
driver also supports GL_ARB_fragment_program. Thus the bump mapping
code is never used on any driver out there. Furthermore, if it is
used, it tends to crash the driver
The signed pixel format is used, as it can be used by pixel shaders or
the ARBfp replacement. However, the format is broken in fglrx, and
negative values are clamped to 0.0. This results in test
failures. WineD3D has an alternative codepath using scale+bias to
enable V8U8 using a standard signed RGB which works correctly on
fglrx.
This is the prefered format of many codecs, and for some codecs this
is the only supported output format. As usual I try to handle all the
conversion in the GPU and keep the CPU involvement minimal to gain the
full performance of PBO transfers.
GL_ARB_fragment_program and GL_ATI_fragment_shader can disable
projected textures properly, and they can also handle
D3DTTFF_PROJECTED | D3DTTFF_COUNT3 properly.
There's no need to do that with the nvts and opengl ffp fixed function
fragment pipeline, it's perfectly well defined in GL which one takes
effect. This removes a few more troubles when switching between
shaders and arbfp.
If a format is not supported natively by opengl, a shader may be able
to convert it. Up to now, CheckDeviceFormat had magic knowldge which
GL extensions lead to which supported format. This patch adds
functions that allow CheckDeviceFormat to ask the actual
implementation for its capabilities.
Henri Verbeet