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#ifndef UNITY_ATMOSPHERIC_SCATTERING_INCLUDED
#define UNITY_ATMOSPHERIC_SCATTERING_INCLUDED
#include "ShaderLibrary/VolumeRendering.hlsl"
#include "AtmosphericScattering.cs.hlsl"
#include "../SkyVariables.hlsl"
#include "../../ShaderVariables.hlsl"
#ifdef VOLUMETRIC_LIGHTING_ENABLED
TEXTURE3D(_VBufferLighting);
#endif
CBUFFER_START(AtmosphericScattering)
float _AtmosphericScatteringType;
// Common
float _FogColorMode;
float4 _FogColorDensity; // color in rgb, density in alpha
float4 _MipFogParameters;
// Linear fog
float4 _LinearFogParameters;
// Exp fog
float4 _ExpFogParameters;
CBUFFER_END
#define _MipFogNear _MipFogParameters.x
#define _MipFogFar _MipFogParameters.y
#define _MipFogMaxMip _MipFogParameters.z
#define _FogDensity _FogColorDensity.w
#define _FogColor _FogColorDensity
#define _LinearFogStart _LinearFogParameters.x
#define _LinearFogEnd _LinearFogParameters.y
#define _LinearFogOneOverRange _LinearFogParameters.z
#define _ExpFogDistance _ExpFogParameters.x
float3 GetFogColor(PositionInputs posInput)
{
if (_FogColorMode == FOGCOLORMODE_CONSTANT_COLOR)
{
return _FogColor.rgb;
}
else if (_FogColorMode == FOGCOLORMODE_SKY_COLOR)
{
// Based on Uncharted 4 "Mip Sky Fog" trick: http://advances.realtimerendering.com/other/2016/naughty_dog/NaughtyDog_TechArt_Final.pdf
float mipLevel = (1.0 - _MipFogMaxMip * saturate((posInput.linearDepth - _MipFogNear) / (_MipFogFar - _MipFogNear))) * _SkyTextureMipCount;
float3 dir = normalize(posInput.positionWS - GetPrimaryCameraPosition());
return SampleSkyTexture(dir, mipLevel).rgb;
}
else // Should not be possible.
return float3(0.0, 0.0, 0.0);
}
// Returns fog color in rgb and fog factor in alpha.
float4 EvaluateAtmosphericScattering(PositionInputs posInput)
{
#ifdef VOLUMETRIC_LIGHTING_ENABLED
return SampleInScatteredRadianceAndTransmittance(TEXTURE3D_PARAM(_VBufferLighting, s_linear_clamp_sampler),
posInput.positionNDC, posInput.linearDepth,
_VBufferResolutionAndScale.zw,
_VBufferDepthEncodingParams);
#endif
float3 fogColor; float fogFactor;
if (_AtmosphericScatteringType == FOGTYPE_EXPONENTIAL)
{
fogColor = GetFogColor(posInput);
fogFactor = _FogDensity * (1.0f - TransmittanceHomogeneousMedium(1.0f / _ExpFogDistance, posInput.linearDepth));
}
else if (_AtmosphericScatteringType == FOGTYPE_LINEAR)
{
fogColor = GetFogColor(posInput);
fogFactor = _FogDensity * saturate((posInput.linearDepth - _LinearFogStart) * _LinearFogOneOverRange);
return float4(fogColor, fogFactor);
}
else // NONE
{
return float4(0.0, 0.0, 0.0, 0.0);
}
return float4(fogColor * fogFactor, fogFactor); // Premultiplied alpha
}
#endif