Fog, Depth, and Shading Mode Changes

When D3DRS_SHADEMODE is set for flat shading during clipping and triangle rasterization, attributes with D3DDECLUSAGE_COLOR are interpolated as flat shaded. If any components of a register are declared with a color semantic but other components of the same register are given different semantics, flat shading interpolation (linear vs. flat) will be undefined on the components in that register without a color semantic.

If fog rendering is desired, vs_3_0 and ps_3_0 shaders must implement fog. No fog calculations are done outside of the shaders. There is no fog register in vs_3_0 and additional semantics D3DDECLUSAGE_FOG (for fog blend factor computed per vertex) and D3DDECLUSAGE_DEPTH"/> (for passing in a depth value to the pixel shader to compute the fog blend factor) have been added.

Texture stage state D3DTSS_TEXCOORDINDEX is ignored when using pixel shader 3.0.

간략하게 요약하자면

Shader 3.0 에서 Fog 연산은 Default 옵션은 아니고

D3DDECLUSAGE_FOG 를 추가해서 사용하거나

PixelShader 에서 직접 연산 처리를 해줘야 한다.