DX10 cards support 512(ATI) or 1024(Nvidia) vertex shader constants in
GL. The dx9 DXCapsViewer shows that dx10 windows drivers only claim
256 constants on Windows, so we can and should do the same.
Internally we want to store some extra data, like ffp_valid. One of the later
patches also stores the format desc in the declaration elements, instead of
the current WINED3DDECLTYPE.
Comparing gl_shaders against NULL after potentially dereferencing it a few
lines earlier probably confuses Coverity. Checking num_gl_shaders instead
should avoid this.
A number of considerations contribute to this:
1) The shader backend knows best which shader(s) it needs. GLSL needs
both, arb only one
2) The shader backend may pass some parameters to the compilation
code(e.g. which pixel format fixup to use)
3) The structures used in (2) are different in vs and ps, so a
baseshader::Compile won't work
4) The structures in (2) are wined3d-private structures, so
having a public method in the vtable won't work(its a bad idea
anyway).
Generating the shader ID and parts of the shader prolog and epilog was
done by the common vertexshader.c / pixelshader.c, which is ugly.
This patch doesn't get rid of all the uglyness, somewhen we'll still
have to sort out the relationship of [arb|glsl]_generate_shader and
[arb|glsl]_generate_declarations.
The GL_ARB_vertex_program extension does not define a standard value for
output texture coordinates. This makes problems when using vertex
shaders with fixed function fragment processing because fffp divides the
texture coords by its .w component. This means that gl shaders have to
write to the .w component of texture coords. Direct3D shaders however
do not.
If an attribute has type D3DDECLTYPE_D3DCOLOR, the red and blue channels
are swizzled in the shader. Since the attribute is stored in the vertex
declaration and not the vertex shader, it can change by setting a new
vertex declaration. If this happens, we have to recompile the shader
with the swizzling of that specific attribute turned on or off.