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96 行
3.0 KiB
96 行
3.0 KiB
float4 GetTessellationFactors(float3 p0, float3 p1, float3 p2, float3 n0, float3 n1, float3 n2)
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{
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float maxDisplacement = GetMaxDisplacement();
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bool frustumCulled = WorldViewFrustumCull(p0, p1, p2, maxDisplacement, (float4[4])unity_CameraWorldClipPlanes);
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bool faceCull = false;
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#if !(defined(_DOUBLESIDED) || defined(_DOUBLESIDED_LIGHTING_FLIP) || defined(_DOUBLESIDED_LIGHTING_MIRROR))
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// TODO: Handle inverse culling (for mirror)!
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if (_TessellationBackFaceCullEpsilon > -0.99) // Is backface culling enabled ?
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{
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faceCull = BackFaceCullTriangle(p0, p1, p2, _TessellationBackFaceCullEpsilon, _WorldSpaceCameraPos);
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}
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#endif
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if (frustumCulled || faceCull)
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{
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// Settings factor to 0 will kill the triangle
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return float4(0.0, 0.0, 0.0, 0.0);
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}
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float3 tessFactor = float3(1.0, 1.0, 1.0);
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// Aaptive screen space tessellation
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if (_TessellationFactorTriangleSize > 0.0)
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{
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// return a value between 0 and 1
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tessFactor *= GetScreenSpaceTessFactor( p0, p1, p2, GetWorldToHClipMatrix(), _ScreenParams, _TessellationFactorTriangleSize);
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}
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// Distance based tessellation
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if (_TessellationFactorMaxDistance > 0.0)
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{
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float3 distFactor = GetDistanceBasedTessFactor(p0, p1, p2, _WorldSpaceCameraPos, _TessellationFactorMinDistance, _TessellationFactorMaxDistance);
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// We square the disance factor as it allow a better percptual descrease of vertex density.
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tessFactor *= distFactor * distFactor;
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}
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tessFactor *= _TessellationFactor;
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// TessFactor below 1.0 have no effect. At 0 it kill the triangle, so clamp it to 1.0
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tessFactor.xyz = float3(max(1.0, tessFactor.x), max(1.0, tessFactor.y), max(1.0, tessFactor.z));
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return CalcTriEdgeTessFactors(tessFactor);
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}
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// tessellationFactors
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// x - 1->2 edge
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// y - 2->0 edge
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// z - 0->1 edge
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// w - inside tessellation factor
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float3 GetTessellationDisplacement(VaryingsMeshToDS input)
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{
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// This call will work for both LayeredLit and Lit shader
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LayerTexCoord layerTexCoord;
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GetLayerTexCoord(
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#ifdef VARYINGS_DS_NEED_TEXCOORD0
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input.texCoord0,
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#else
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float2(0.0, 0.0),
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#endif
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#ifdef VARYINGS_DS_NEED_TEXCOORD1
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input.texCoord1,
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#else
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float2(0.0, 0.0),
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#endif
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#ifdef VARYINGS_DS_NEED_TEXCOORD2
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input.texCoord2,
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#else
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float2(0.0, 0.0),
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#endif
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#ifdef VARYINGS_DS_NEED_TEXCOORD3
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input.texCoord3,
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#else
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float2(0.0, 0.0),
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#endif
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input.positionWS,
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input.normalWS,
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layerTexCoord);
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// http://www.sebastiansylvan.com/post/the-problem-with-tessellation-in-directx-11/
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float lod = 0.0;
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float4 vertexColor = float4(0.0, 0.0, 0.0, 0.0);
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#ifdef VARYINGS_DS_NEED_COLOR
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vertexColor = input.color;
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#endif
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float height = ComputePerVertexDisplacement(layerTexCoord, vertexColor, lod);
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float3 displ = height * input.normalWS;
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// Applying scaling of the object if requested
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#ifdef _TESSELLATION_OBJECT_SCALE
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displ *= input.objectScale;
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#endif
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return displ;
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}
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