Overwiew
NV04_DX5_TEXTURED_TRIANGLE -> NV04_CONTEXT_SURFACES_3D -> COLOR & ZETA -buffers in FB mem.
Buffers
Z (24 bit)- and stencil(8bit) buffer share the same space. Color buffer is in separate mem space.
To do a clear of a buffer the driver sets up the NV04_SURFACE (format = Y32, source, destin = offset of buffer), then draws an NV04_GDI_RECTANGLE_TEXT (op=srccopy).
To clear Z-buffer, fill_value = 0xffffff00, pattern0,1 = 0x77777777. For stencil buffer fill_value = 0x000000ff, pattern0,1 = 0x88888888. For both, fill_value = 0xffffffff, no patterns used.
Fog
Enable BLEND_FOG, set FOG_COLOR to ecessary color. Then set SPECULAR alpha component to the vertex color weight in fog equation. Fog weights should be computed by sofware.