110 lines
3.8 KiB
Markdown
110 lines
3.8 KiB
Markdown
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## PBR Refrection（有问题）
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```
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//input anteriorChamberDepth 贴图 使用HeightMap
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//input radius
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//input mask 贴图
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//input texcoord
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//input n 折射率比值
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//input frontNormalW 贴图float3(0,0,1) Local=>World
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// 角膜区域突起的模型 height = max(-positionL.z – eyeIrisDepth, 0.0);
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// 球形模型 Plot[Max[1.0 - 18.4 * r * r, 0.0], {r, 0, 0.3}]
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float height = anteriorChamberDepth ;//* saturate( 1.0 - 18.4 * radius * radius );
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float3 normalW=Parameters.WorldNormal;
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float3 viewW= mul(float3(0,0,1),(float3x3)View.ViewToTranslatedWorld);//CameraViewToTranslatedWorld
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// refractedW
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float w = n * dot( normalW, viewW );
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float k = sqrt( 1.0 + ( w - n ) * ( w + n ) );
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float3 refractedW = ( w - k ) * normalW - n * viewW;
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refractedW=-normalize(refractedW);
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//float3 frontNormalW=mul(float(0,0,1),float(3x3)GetPrimitiveData(Parameters.PrimitiveId).LocalToWorld) * -1;
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float cosAlpha = dot(frontNormalW, refractedW);
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float dist = height / cosAlpha;
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float3 offsetW = dist * refractedW;
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float2 offsetL = mul(offsetW, (float3x2)GetPrimitiveData(Parameters.PrimitiveId).WorldToLocal);
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texcoord += float2(mask, -mask) * offsetL;
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return texcoord;
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```
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### 原始代码
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```
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// 角膜区域突起的模型
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// Alternatively, use a displacement map
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// height = max(-positionL.z – eyeIrisDepth, 0.0);
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// 球形模型
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// Plot[Max[1.0 - 18.4 * r * r, 0.0], {r, 0, 0.3}]
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height = anteriorChamberDepth * saturate( 1.0 - 18.4 * radius * radius );
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// refractedW
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float w = n * dot( normalW, viewW );
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float k = sqrt( 1.0 + ( w - n ) * ( w + n ) );
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float3 refractedW = ( w - k ) * normalW - n * viewW;
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float cosAlpha = dot(frontNormalW, -refractedW);
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float dist = height / cosAlpha;
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float3 offsetW = dist * refractedW;
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float2 offsetL = mul(offsetW, (float3x2) worldInverse);
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texcoord += float2(mask, -mask) * offsetL;
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```
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## Matcap反射效果
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```
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float2 CalcMatcapUV(FMaterialPixelParameters Parameters,float3 normalTexture)
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{
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float3 ViewVector=Parameters.CameraVector * -1;
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float3 ViewSpaceRightVector=normalize(cross(ViewVector , mul( float3(0.0,1.0,0.0) , ResolvedView.ViewToTranslatedWorld )));
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float3 ViewSpaceUpVector=cross(ViewVector ,ViewSpaceRightVector);
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float3x3 Matrix=float3x3(
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ViewSpaceRightVector.x,ViewSpaceUpVector.x,ViewVector.x,
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ViewSpaceRightVector.y,ViewSpaceUpVector.y,ViewVector.y,
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ViewSpaceRightVector.z,ViewSpaceUpVector.z,ViewVector.z
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);
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float3 ZeroOneNormal=mul(normalize(Parameters.WorldNormal+normalTexture),Matrix)*0.5+0.5;
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return float2(ZeroOneNormal.x,ZeroOneNormal.y*-1);
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}
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```
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### 这个不太行
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```
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//input normalTexture 法线贴图
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float3 TangentWS=Parameters.TangentToWorld[0];
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float3 NormalWS=Parameters.TangentToWorld[2];
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float3 BinormalWS=cross(NormalWS, TangentWS);
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float3 worldNormal;
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worldNormal.x = dot(float3(TangentWS.x,BinormalWS.x,NormalWS.x), normalTexture);
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worldNormal.y = dot(float3(TangentWS.y,BinormalWS.y,NormalWS.y), normalTexture);
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worldNormal.z = dot(float3(TangentWS.z,BinormalWS.z,NormalWS.z), normalTexture);
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worldNormal = normalize(worldNormal);
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float3 e = normalize(GetWorldPosition(Parameters) - ResolvedView.WorldCameraOrigin);
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float3 reflectVector = reflect(e, worldNormal);
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float3 reflectVectorVS = normalize(mul(reflectVector,ResolvedView.TranslatedWorldToView));
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float m = 2.82842712474619 * sqrt(reflectVectorVS.z + 1.0);
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float2 cap = reflectVectorVS.xy / m + 0.5;
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cap=cap*0.5 + 0.5;
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return cap;
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```
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## 高光贴图位置调整
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```
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//input float2 LeftUp,LeftDown,RightUp,RightDown;
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float3 viewW = mul(float3(0,0,1),(float3x3)View.ViewToTranslatedWorld);
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float3 viewL = mul(viewW, (float3x2)GetPrimitiveData(Parameters.PrimitiveId).WorldToLocal);
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float2 viewL2D = normalize(viewL.xy);
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float2 Left=lerp(LeftUp,LeftDown,viewL2D.y);
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float2 Right=lerp(RightUp,RightDown,viewL2D.y);
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return lerp(Left,Right,viewL2D.x);
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```
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## 焦散
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- dot(Parameters.WorldNormal,View.DirectionalLightDirection);
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- Fresnel
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乘以焦散Mask即可
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