178 lines
8.1 KiB
HLSL
178 lines
8.1 KiB
HLSL
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#if defined(SHADER_API_XBOXONE) || defined(SHADER_API_PSSL)
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// AMD recommand this value for GCN http://amd-dev.wpengine.netdna-cdn.com/wordpress/media/2013/05/GCNPerformanceTweets.pdf
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#define MAX_TESSELLATION_FACTORS 15.0
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#else
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#define MAX_TESSELLATION_FACTORS 64.0
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#endif
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float4 GetTessellationFactors(float3 p0, float3 p1, float3 p2, float3 n0, float3 n1, float3 n2, float3 inputTessellationFactors)
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{
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float maxDisplacement = GetMaxDisplacement();
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// For tessellation we want to process tessellation factor always from the point of view of the camera (to be consistent and avoid Z-fight).
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// For the culling part however we want to use the current view (shadow view).
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// Thus the following code play with both.
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float frustumEps = -maxDisplacement; // "-" Expected parameter for CullTriangleEdgesFrustum
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#if !defined(SCENESELECTIONPASS) && !defined(SCENEPICKINGPASS)
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// TODO: the only reason I test the near plane here is that I am not sure that the product of other tessellation factors
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// (such as screen-space/distance-based) results in the tessellation factor of 1 for the geometry behind the near plane.
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// If that is the case (and, IMHO, it should be), we shouldn't have to test the near plane here.
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bool4 frustumCullEdgesMainView = CullFullTriangleAndEdgesFrustum(p0, p1, p2, frustumEps, _FrustumPlanes, 5); // Do not test the far plane
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#else
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// During the scene picking pass, we have no access to camera frustum planes
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bool4 frustumCullEdgesMainView = false;
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#endif
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#if defined(SHADERPASS) && (SHADERPASS != SHADERPASS_SHADOWS)
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bool frustumCullCurrView = frustumCullEdgesMainView.w;
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#else
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bool frustumCullCurrView = CullTriangleFrustum(p0, p1, p2, frustumEps, _ShadowFrustumPlanes, 4); // Do not test near/far planes
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#endif
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bool faceCull = false;
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#if !defined(_DOUBLESIDED_ON) && !defined(SCENESELECTIONPASS) && !defined(SCENEPICKINGPASS)
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if (_TessellationBackFaceCullEpsilon > -1.0) // Is back-face culling enabled ?
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{
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// Handle transform mirroring (like negative scaling)
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// Note: We don't need to handle handness of view matrix here as the backface is perform in worldspace
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// note2: When we have an orthogonal matrix (cascade shadow map), we need to use the direction of the light.
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// Otherwise we use only p0 instead of the mean of P0, p1,p2 to save ALU as with tessellated geomerty it is rarely needed and user can still control _TessellationBackFaceCullEpsilon.
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float winding = unity_WorldTransformParams.w;
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faceCull = CullTriangleBackFaceView(p0, p1, p2, _TessellationBackFaceCullEpsilon, GetWorldSpaceNormalizeViewDir(p0), winding); // Use shadow view
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}
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#endif
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if (frustumCullCurrView || faceCull)
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{
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// Settings factor to 0 will kill the triangle
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return 0;
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}
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// For performance reasons, we choose not to tessellate outside of the main camera view
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// (we perform this test both during the regular scene rendering and the shadow pass).
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// For edges not visible from the main view, our goal is to set the tessellation factor to 1.
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// In this case, we set the tessellation factor to 0 here.
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// That way, all scaling of this tessellation factor will still result in 0.
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// Before we call CalcTriTessFactorsFromEdgeTessFactors(), all factors are clamped by max(f, 1),
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// which achieves the desired effect.
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float3 edgeTessFactors = float3(frustumCullEdgesMainView.x ? 0 : 1, frustumCullEdgesMainView.y ? 0 : 1, frustumCullEdgesMainView.z ? 0 : 1);
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// Adaptive 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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// Warning: '_ViewProjMatrix' can be the viewproj matrix of the light when we render shadows, that's why we use _CameraViewProjMatrix instead
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edgeTessFactors *= GetScreenSpaceTessFactor(p0, p1, p2, _CameraViewProjMatrix, _ScreenSize, _TessellationFactorTriangleSize); // Use primary camera view
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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, GetPrimaryCameraPosition(), _TessellationFactorMinDistance, _TessellationFactorMaxDistance); // Use primary camera view
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// We square the disance factor as it allow a better percptual descrease of vertex density.
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edgeTessFactors *= distFactor * distFactor;
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}
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edgeTessFactors *= inputTessellationFactors * _GlobalTessellationFactorMultiplier;
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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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edgeTessFactors = max(edgeTessFactors, float3(1.0, 1.0, 1.0));
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return CalcTriTessFactorsFromEdgeTessFactors(edgeTessFactors);
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}
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struct TessellationFactors
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{
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float edge[3] : SV_TessFactor;
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float inside : SV_InsideTessFactor;
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};
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TessellationFactors HullConstant(InputPatch<PackedVaryingsToDS, 3> input)
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{
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UNITY_SETUP_INSTANCE_ID(input[0].vmesh);
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VaryingsToDS varying0 = UnpackVaryingsToDS(input[0]);
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VaryingsToDS varying1 = UnpackVaryingsToDS(input[1]);
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VaryingsToDS varying2 = UnpackVaryingsToDS(input[2]);
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float3 p0 = varying0.vmesh.positionRWS;
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float3 p1 = varying1.vmesh.positionRWS;
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float3 p2 = varying2.vmesh.positionRWS;
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float3 n0 = varying0.vmesh.normalWS;
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float3 n1 = varying1.vmesh.normalWS;
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float3 n2 = varying2.vmesh.normalWS;
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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 (calculate as mean of three in GetTessellationFactors())
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float3 inputTessellationFactors;
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// TessellatinFactor is evaluate in vertex shader
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inputTessellationFactors.x = 0.5 * (varying1.vmesh.tessellationFactor + varying2.vmesh.tessellationFactor);
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inputTessellationFactors.y = 0.5 * (varying2.vmesh.tessellationFactor + varying0.vmesh.tessellationFactor);
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inputTessellationFactors.z = 0.5 * (varying0.vmesh.tessellationFactor + varying1.vmesh.tessellationFactor);
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float4 tf = GetTessellationFactors(p0, p1, p2, n0, n1, n2, inputTessellationFactors);
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TessellationFactors output;
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output.edge[0] = min(tf.x, MAX_TESSELLATION_FACTORS);
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output.edge[1] = min(tf.y, MAX_TESSELLATION_FACTORS);
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output.edge[2] = min(tf.z, MAX_TESSELLATION_FACTORS);
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output.inside = min(tf.w, MAX_TESSELLATION_FACTORS);
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return output;
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}
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// ref: http://reedbeta.com/blog/tess-quick-ref/
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[maxtessfactor(MAX_TESSELLATION_FACTORS)]
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[domain("tri")]
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[partitioning("fractional_odd")]
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[outputtopology("triangle_cw")]
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[patchconstantfunc("HullConstant")]
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[outputcontrolpoints(3)]
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PackedVaryingsToDS Hull(InputPatch<PackedVaryingsToDS, 3> input, uint id : SV_OutputControlPointID)
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{
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// Pass-through
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return input[id];
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}
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[domain("tri")]
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PackedVaryingsToPS Domain(TessellationFactors tessFactors, const OutputPatch<PackedVaryingsToDS, 3> input, float3 baryCoords : SV_DomainLocation)
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{
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UNITY_SETUP_INSTANCE_ID(input[0].vmesh);
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VaryingsToDS varying0 = UnpackVaryingsToDS(input[0]);
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VaryingsToDS varying1 = UnpackVaryingsToDS(input[1]);
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VaryingsToDS varying2 = UnpackVaryingsToDS(input[2]);
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VaryingsToDS varying = InterpolateWithBaryCoordsToDS(varying0, varying1, varying2, baryCoords);
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// We have Phong tessellation in all case where we don't have displacement only
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#ifdef _TESSELLATION_PHONG
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float3 p0 = varying0.vmesh.positionRWS;
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float3 p1 = varying1.vmesh.positionRWS;
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float3 p2 = varying2.vmesh.positionRWS;
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float3 n0 = varying0.vmesh.normalWS;
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float3 n1 = varying1.vmesh.normalWS;
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float3 n2 = varying2.vmesh.normalWS;
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varying.vmesh.positionRWS = PhongTessellation( varying.vmesh.positionRWS,
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p0, p1, p2, n0, n1, n2,
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baryCoords, _TessellationShapeFactor);
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#endif
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#ifdef VARYINGS_DS_NEED_POSITIONPREDISPLACEMENT
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varying.vmesh.positionPredisplacementRWS = varying.vmesh.positionRWS;
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#endif
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#ifdef HAVE_TESSELLATION_MODIFICATION
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varying.vmesh = ApplyTessellationModification(varying.vmesh, _TimeParameters.xyz);
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#endif
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return VertTesselation(varying);
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}
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