// - _ENABLE_FOG_ON_TRANSPARENT if fog is enable on transparent surface
//-----------------------------------------------------------------------------
// ApplyBlendMode function
//-----------------------------------------------------------------------------
float4 ApplyBlendMode(float3 diffuseLighting, float3 specularLighting, float opacity)
{
// ref: http://advances.realtimerendering.com/other/2016/naughty_dog/NaughtyDog_TechArt_Final.pdf
// Lit transparent object should have reflection and tramission.
// Transmission when not using "rough refraction mode" (with fetch in preblured background) is handled with blend mode.
// However reflection should not be affected by blend mode. For example a glass should still display reflection and not lose the highlight when blend
// This is the purpose of following function, "Cancel" the blend mode effect on the specular lighting but not on the diffuse lighting
#ifdef _BLENDMODE_PRESERVE_SPECULAR_LIGHTING
// In the case of _BLENDMODE_ALPHA the code should be float4(diffuseLighting + (specularLighting / max(opacity, 0.01)), opacity)
// However this have precision issue when reaching 0, so we change the blend mode and apply src * src_a inside the shader instead
#if defined(_BLENDMODE_ADD) || defined(_BLENDMODE_ALPHA)
return float4(diffuseLighting * opacity + specularLighting, opacity);
#else // defined(_BLENDMODE_MULTIPLY) || defined(_BLENDMODE_PRE_MULTIPLY)
return float4(diffuseLighting + specularLighting, opacity);
#endif
#else
#if defined(_BLENDMODE_ADD) || defined(_BLENDMODE_ALPHA)
return float4((diffuseLighting + specularLighting) * opacity, opacity);
#else // defined(_BLENDMODE_MULTIPLY) || defined(_BLENDMODE_PRE_MULTIPLY)
return float4(diffuseLighting + specularLighting, opacity);
#endif
#endif
}
float4 ApplyBlendMode(float3 color, float opacity)
{
return ApplyBlendMode(color, float3(0.0, 0.0, 0.0), opacity);
}
//-----------------------------------------------------------------------------
// This must be call after ApplyBlendMode to work correctly
float4 EvaluateAtmosphericScattering(PositionInputs posInput, float4 inputColor)
{
float4 result = inputColor;
#if defined(_BLENDMODE_ALPHA)
// Regular alpha blend only need a lerp to work
result.rgb = lerp(result.rgb, fog.rgb, fog.a);
// Regular alpha blend need to multiply fog color by opacity (as we do src * src_a inside the shader)
result.rgb = lerp(result.rgb, fog.rgb * result.a , fog.a);
#elif defined(_BLENDMODE_ADD)
// For additive, we just need to fade to black with fog density (black + background == background color == fog color)
result.rgb = result.rgb * (1.0 - fog.a);
// For Pre-Multiplied Alpha Blend, we need to multiply fog color by src alpha to match regular alpha blending formula.
result.rgb = lerp(result.rgb, fog.rgb * result.a, fog.a);
#endif
#else
// Evaluation of fog for opaque objects is currently done in a full screen pass independent from any material parameters.
// but this funtction is called in generic forward shader code so we need it to be neutral in this case.
sebastienlagarde
7 年前