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107 行
4.3 KiB
107 行
4.3 KiB
#ifndef UNITY_ATMOSPHERIC_SCATTERING_INCLUDED
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#define UNITY_ATMOSPHERIC_SCATTERING_INCLUDED
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#include "CoreRP/ShaderLibrary/VolumeRendering.hlsl"
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#include "CoreRP/ShaderLibrary/Filtering.hlsl"
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#include "AtmosphericScattering.cs.hlsl"
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#include "../SkyVariables.hlsl"
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#include "../../ShaderVariables.hlsl"
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#include "../../Lighting/Volumetrics/VBuffer.hlsl"
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#if (SHADEROPTIONS_VOLUMETRIC_LIGHTING_PRESET != 0)
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TEXTURE3D(_VBufferLighting);
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#endif
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CBUFFER_START(AtmosphericScattering)
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int _AtmosphericScatteringType;
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// Common
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float _FogColorMode;
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float4 _FogColorDensity; // color in rgb, density in alpha
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float4 _MipFogParameters;
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// Linear fog
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float4 _LinearFogParameters;
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// Exp fog
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float4 _ExpFogParameters;
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CBUFFER_END
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#define _MipFogNear _MipFogParameters.x
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#define _MipFogFar _MipFogParameters.y
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#define _MipFogMaxMip _MipFogParameters.z
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#define _FogDensity _FogColorDensity.w
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#define _FogColor _FogColorDensity
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#define _LinearFogStart _LinearFogParameters.x
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#define _LinearFogOneOverRange _LinearFogParameters.y
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#define _LinearFogHeightEnd _LinearFogParameters.z
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#define _LinearFogHeightOneOverRange _LinearFogParameters.w
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#define _ExpFogDistance _ExpFogParameters.x
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#define _ExpFogBaseHeight _ExpFogParameters.y
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#define _ExpFogHeightAttenuation _ExpFogParameters.z
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float3 GetFogColor(PositionInputs posInput)
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{
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if (_FogColorMode == FOGCOLORMODE_CONSTANT_COLOR)
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{
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return _FogColor.rgb;
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}
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else if (_FogColorMode == FOGCOLORMODE_SKY_COLOR)
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{
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// Based on Uncharted 4 "Mip Sky Fog" trick: http://advances.realtimerendering.com/other/2016/naughty_dog/NaughtyDog_TechArt_Final.pdf
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float mipLevel = (1.0 - _MipFogMaxMip * saturate((posInput.linearDepth - _MipFogNear) / (_MipFogFar - _MipFogNear))) * _SkyTextureMipCount;
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float3 dir = -GetWorldSpaceNormalizeViewDir(posInput.positionWS);
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return SampleSkyTexture(dir, mipLevel).rgb;
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}
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else // Should not be possible.
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return float3(0.0, 0.0, 0.0);
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}
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// Returns fog color in rgb and fog factor in alpha.
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float4 EvaluateAtmosphericScattering(PositionInputs posInput)
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{
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float3 fogColor = 0;
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float fogFactor = 0;
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switch (_AtmosphericScatteringType)
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{
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case FOGTYPE_LINEAR:
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{
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fogColor = GetFogColor(posInput);
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fogFactor = _FogDensity * saturate((posInput.linearDepth - _LinearFogStart) * _LinearFogOneOverRange) * saturate((_LinearFogHeightEnd - GetAbsolutePositionWS(posInput.positionWS).y) * _LinearFogHeightOneOverRange);
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break;
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}
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case FOGTYPE_EXPONENTIAL:
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{
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fogColor = GetFogColor(posInput);
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float distance = length(GetWorldSpaceViewDir(posInput.positionWS));
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float fogHeight = max(0.0, GetAbsolutePositionWS(posInput.positionWS).y - _ExpFogBaseHeight);
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fogFactor = _FogDensity * TransmittanceHomogeneousMedium(_ExpFogHeightAttenuation, fogHeight) * (1.0f - TransmittanceHomogeneousMedium(1.0f / _ExpFogDistance, distance));
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break;
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}
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case FOGTYPE_VOLUMETRIC:
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{
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#if (SHADEROPTIONS_VOLUMETRIC_LIGHTING_PRESET != 0)
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float4 volFog = SampleVolumetricLighting(TEXTURE3D_PARAM(_VBufferLighting, s_linear_clamp_sampler),
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posInput.positionNDC,
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posInput.linearDepth,
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_VBufferResolution,
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_VBufferSliceCount.xy,
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_VBufferUvScaleAndLimit.xy,
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_VBufferUvScaleAndLimit.zw,
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_VBufferDepthEncodingParams,
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_VBufferDepthDecodingParams,
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true, true);
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fogFactor = 1 - volFog.a; // Opacity from transmittance
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fogColor = volFog.rgb * min(rcp(fogFactor), FLT_MAX); // Un-premultiply, clamp to avoid (0 * INF = NaN)
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#endif
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break;
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}
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}
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return float4(fogColor, fogFactor);
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}
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#endif
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