float GetInverseTilingScale()
{
#ifdef _PER_PIXEL_DISPLACEMENT_TILING_SCALE
return rcp(0.5 * abs(_BaseColorMap_ST.x) + 0.5 * abs(_BaseColorMap_ST.y)); // TODO: precompute
return rcp(0.5 * abs(_BaseColorMap_ST.x) + 0.5 * abs(_BaseColorMap_ST.y)); // TODO: precompute
#else
return 1;
#endif
{
bool ppdEnable = false;
bool isPlanar = false;
bool isTriplanar = false;
#if defined(_PER_PIXEL_DISPLACEMENT) && defined(_HEIGHTMAP)
// These variables are known at the compile time.
bool isPlanar = layerTexCoord.base.mappingType == UV_MAPPING_PLANAR;
bool isTriplanar = layerTexCoord.base.mappingType == UV_MAPPING_TRIPLANAR;
#if defined(_PER_PIXEL_DISPLACEMENT) && defined(_HEIGHTMAP)
// All variable are compile time value
ppdEnable = true;
isPlanar = layerTexCoord.base.mappingType == UV_MAPPING_PLANAR;
isTriplanar = layerTexCoord.base.mappingType == UV_MAPPING_TRIPLANAR;
#endif
// See comment in layered version for details
float2 worldScales = isPlanar ? float2(_TexWorldScale, rcp(_TexWorldScale)) : 1; // TODO: precompute
float2 invPrimScale = isPlanar ? 1 : rcp(float2(_PPDPrimitiveLength, _PPDPrimitiveWidth)); // TODO: precompute
float maxHeight = GetMaxDisplacement() * GetInverseTilingScale() * worldScales.x;
float2 minUvSize = GetMinUvSize(layerTexCoord);
float lod = ComputeTextureLOD(minUvSize);
if (ppdEnable)
{
// See comment in layered version for details
float2 worldScales = isPlanar ? float2(_TexWorldScale, rcp(_TexWorldScale)) : 1; // TODO: precompute
float2 invPrimScale = isPlanar ? 1 : rcp(float2(_PPDPrimitiveLength, _PPDPrimitiveWidth)); // TODO: precompute
float maxHeight = GetMaxDisplacement() * GetInverseTilingScale() * worldScales.x;
float2 minUvSize = GetMinUvSize(layerTexCoord);
float lod = ComputeTextureLOD(minUvSize);
PerPixelHeightDisplacementParam ppdParam;
PerPixelHeightDisplacementParam ppdParam;
float height; // final height processed
float NdotV;
float height; // final height processed
float NdotV;
// planar/triplanar
float2 uvXZ;
float2 uvXY;
float2 uvZY;
GetTriplanarCoordinate(V, uvXZ, uvXY, uvZY);
// planar/triplanar
float2 uvXZ;
float2 uvXY;
float2 uvZY;
GetTriplanarCoordinate(V, uvXZ, uvXY, uvZY);
// TODO: support object space planar/triplanar ?
// TODO: support object space planar/triplanar ?
// We need to calculate the texture space direction. It depends on the mapping.
if (isTriplanar)
{
float3 viewDirTS;
float planeHeight;
int numSteps;
// We need to calculate the texture space direction. It depends on the mapping.
if (isTriplanar)
{
float3 viewDirTS;
float planeHeight;
int numSteps;
// Perform a POM in each direction and modify appropriate texture coordinate
ppdParam.uv = layerTexCoord.base.uvZY;
viewDirTS = float3(V.x > 0.0 ? uvZY : -uvZY, V.x);
numSteps = (int)lerp(_PPDMaxSamples, _PPDMinSamples, viewDirTS.z);
float2 offsetZY = ParallaxOcclusionMapping(lod, _PPDLodThreshold, numSteps, viewDirTS, maxHeight, ppdParam, planeHeight);
// Perform a POM in each direction and modify appropriate texture coordinate
ppdParam.uv = layerTexCoord.base.uvZY;
viewDirTS = float3(V.x > 0.0 ? uvZY : -uvZY, V.x);
numSteps = (int)lerp(_PPDMaxSamples, _PPDMinSamples, viewDirTS.z);
float2 offsetZY = ParallaxOcclusionMapping(lod, _PPDLodThreshold, numSteps, viewDirTS, maxHeight, ppdParam, planeHeight);
// Apply offset to all triplanar UVSet
layerTexCoord.base.uvZY += offsetZY;
layerTexCoord.details.uvZY += offsetZY;
height = layerTexCoord.triplanarWeights.x * planeHeight;
// Apply offset to all triplanar UVSet
layerTexCoord.base.uvZY += offsetZY;
layerTexCoord.details.uvZY += offsetZY;
height = layerTexCoord.triplanarWeights.x * planeHeight;
ppdParam.uv = layerTexCoord.base.uvXZ;
viewDirTS = float3(V.y > 0.0 ? uvXZ : -uvXZ, V.y);
numSteps = (int)lerp(_PPDMaxSamples, _PPDMinSamples, viewDirTS.z);
float2 offsetXZ = ParallaxOcclusionMapping(lod, _PPDLodThreshold, numSteps, viewDirTS, maxHeight, ppdParam, planeHeight);
ppdParam.uv = layerTexCoord.base.uvXZ;
viewDirTS = float3(V.y > 0.0 ? uvXZ : -uvXZ, V.y);
numSteps = (int)lerp(_PPDMaxSamples, _PPDMinSamples, viewDirTS.z);
float2 offsetXZ = ParallaxOcclusionMapping(lod, _PPDLodThreshold, numSteps, viewDirTS, maxHeight, ppdParam, planeHeight);
layerTexCoord.base.uvXZ += offsetXZ;
layerTexCoord.details.uvXZ += offsetXZ;
height += layerTexCoord.triplanarWeights.y * planeHeight;
ppdParam.uv = layerTexCoord.base.uvXY;
viewDirTS = float3(V.z > 0.0 ? uvXY : -uvXY, V.z);
numSteps = (int)lerp(_PPDMaxSamples, _PPDMinSamples, viewDirTS.z);
float2 offsetXY = ParallaxOcclusionMapping(lod, _PPDLodThreshold, numSteps, viewDirTS, maxHeight, ppdParam, planeHeight);
layerTexCoord.base.uvXY += offsetXY;
layerTexCoord.details.uvXY += offsetXY;
height += layerTexCoord.triplanarWeights.z * planeHeight;
layerTexCoord.base.uvXZ += offsetXZ;
layerTexCoord.details.uvXZ += offsetXZ;
height += layerTexCoord.triplanarWeights.y * planeHeight;
NdotV = 1; // TODO.
}
else
{
ppdParam.uv = layerTexCoord.base.uv; // For planar it is uv too, not uvXZ
ppdParam.uv = layerTexCoord.base.uvXY;
viewDirTS = float3(V.z > 0.0 ? uvXY : -uvXY, V.z);
numSteps = (int)lerp(_PPDMaxSamples, _PPDMinSamples, viewDirTS.z);
float2 offsetXY = ParallaxOcclusionMapping(lod, _PPDLodThreshold, numSteps, viewDirTS, maxHeight, ppdParam, planeHeight);
// Note: The TBN is not normalize as it is based on mikkt. We should normalize it, but POM is always use on simple enough surfarce that mean it is not required (save 2 normalize). Tag: SURFACE_GRADIENT
float3 viewDirTS = isPlanar ? float3(uvXZ, V.y) : TransformWorldToTangent(V, input.worldToTangent);
viewDirTS *= GetInverseObjectScale().xzy; // Switch from Y-up to Z-up
layerTexCoord.base.uvXY += offsetXY;
layerTexCoord.details.uvXY += offsetXY;
height += layerTexCoord.triplanarWeights.z * planeHeight;
NdotV = viewDirTS.z;
NdotV = 1; // TODO.
}
else
{
ppdParam.uv = layerTexCoord.base.uv; // For planar it is uv too, not uvXZ
// Transform the view vector into the UV space.
float2 uvSpaceScale = invPrimScale * _BaseColorMap_ST.xy;
float3 viewDirUV = normalize(float3(viewDirTS.xy * uvSpaceScale, viewDirTS.z / maxHeight));
// Note: The TBN is not normalize as it is based on mikkt. We should normalize it, but POM is always use on simple enough surfarce that mean it is not required (save 2 normalize). Tag: SURFACE_GRADIENT
float3 viewDirTS = isPlanar ? float3(uvXZ, V.y) : TransformWorldToTangent(V, input.worldToTangent);
viewDirTS *= GetInverseObjectScale().xzy; // Switch from Y-up to Z-up
float unitAngle = saturate(FastACos(viewDirUV.z) * INV_HALF_PI); // TODO: optimize
int numSteps = (int)lerp(_PPDMinSamples, _PPDMaxSamples, unitAngle);
NdotV = viewDirTS.z;
// POM uses a normalized view vector in the UV space to intersect the heightmap within a 1x1x1 box.
float2 offset = ParallaxOcclusionMapping(lod, _PPDLodThreshold, numSteps, viewDirUV, 1, ppdParam, height);
// Transform the view vector into the UV space.
float2 uvSpaceScale = invPrimScale * _BaseColorMap_ST.xy;
float3 viewDirUV = normalize(float3(viewDirTS.xy * uvSpaceScale, viewDirTS.z / maxHeight));
// Apply offset to all UVSet0 / planar
layerTexCoord.base.uv += offset;
layerTexCoord.details.uv += isPlanar ? offset : _UVDetailsMappingMask.x * offset; // Only apply offset if details map use UVSet0 _UVDetailsMappingMask.x will be 1 in this case, else 0
}
float unitAngle = saturate(FastACos(viewDirUV.z) * INV_HALF_PI); // TODO: optimize
int numSteps = (int)lerp(_PPDMinSamples, _PPDMaxSamples, unitAngle);
maxHeight *= worldScales.y;
// POM uses a normalized view vector in the UV space to intersect the heightmap within a 1x1x1 box.
float2 offset = ParallaxOcclusionMapping(lod, _PPDLodThreshold, numSteps, viewDirUV, 1, ppdParam, height);
// Since POM "pushes" geometry inwards (rather than extrude it), { height = height - 1 }.
// Since the result is used as a 'depthOffsetVS', it needs to be positive, so we flip the sign.
float verticalDisplacement = maxHeight - height * maxHeight;
return verticalDisplacement / NdotV;
// Apply offset to all UVSet0 / planar
layerTexCoord.base.uv += offset;
layerTexCoord.details.uv += isPlanar ? offset : _UVDetailsMappingMask.x * offset; // Only apply offset if details map use UVSet0 _UVDetailsMappingMask.x will be 1 in this case, else 0
maxHeight *= worldScales.y;
// Since POM "pushes" geometry inwards (rather than extrude it), { height = height - 1 }.
// Since the result is used as a 'depthOffsetVS', it needs to be positive, so we flip the sign.
float verticalDisplacement = maxHeight - height * maxHeight;
return verticalDisplacement / NdotV;
#else
#endif
}
// Calculate displacement for per vertex displacement mapping
Evgenii Golubev
7 年前