您最多选择25个主题
主题必须以中文或者字母或数字开头，可以包含连字符 (-)，并且长度不得超过35个字符
226 行
8.7 KiB
226 行
8.7 KiB
#ifndef UNITY_COMMON_MATERIAL_INCLUDED
|
|
#define UNITY_COMMON_MATERIAL_INCLUDED
|
|
|
|
//-----------------------------------------------------------------------------
|
|
// Helper functions for roughness
|
|
//-----------------------------------------------------------------------------
|
|
|
|
real PerceptualRoughnessToRoughness(real perceptualRoughness)
|
|
{
|
|
return perceptualRoughness * perceptualRoughness;
|
|
}
|
|
|
|
real RoughnessToPerceptualRoughness(real roughness)
|
|
{
|
|
return sqrt(roughness);
|
|
}
|
|
|
|
real PerceptualSmoothnessToRoughness(real perceptualSmoothness)
|
|
{
|
|
return (1.0 - perceptualSmoothness) * (1.0 - perceptualSmoothness);
|
|
}
|
|
|
|
real PerceptualSmoothnessToPerceptualRoughness(real perceptualSmoothness)
|
|
{
|
|
return (1.0 - perceptualSmoothness);
|
|
}
|
|
|
|
// Using roughness values of 0 leads to INFs and NANs. The only sensible place to use the roughness
|
|
// value of 0 is IBL, so we do not modify the perceptual roughness which is used to select the MIP map level.
|
|
// Note: making the constant too small results in aliasing.
|
|
real ClampRoughnessForAnalyticalLights(real roughness)
|
|
{
|
|
return max(roughness, 1.0 / 1024.0);
|
|
}
|
|
|
|
void ConvertAnisotropyToRoughness(real perceptualRoughness, real anisotropy, out real roughnessT, out real roughnessB)
|
|
{
|
|
real roughness = PerceptualRoughnessToRoughness(perceptualRoughness);
|
|
|
|
// Use the parametrization of Sony Imageworks.
|
|
// Ref: Revisiting Physically Based Shading at Imageworks, p. 15.
|
|
roughnessT = roughness * (1 + anisotropy);
|
|
roughnessB = roughness * (1 - anisotropy);
|
|
}
|
|
|
|
void ConvertRoughnessToAnisotropy(real roughnessT, real roughnessB, out real anisotropy)
|
|
{
|
|
anisotropy = ((roughnessT - roughnessB) / (roughnessT + roughnessB + 0.0001));
|
|
}
|
|
|
|
// Same as ConvertAnisotropyToRoughness but
|
|
// roughnessT and roughnessB are clamped, and are meant to be used with punctual and directional lights.
|
|
void ConvertAnisotropyToClampRoughness(real perceptualRoughness, real anisotropy, out real roughnessT, out real roughnessB)
|
|
{
|
|
ConvertAnisotropyToRoughness(perceptualRoughness, anisotropy, roughnessT, roughnessB);
|
|
|
|
roughnessT = ClampRoughnessForAnalyticalLights(roughnessT);
|
|
roughnessB = ClampRoughnessForAnalyticalLights(roughnessB);
|
|
}
|
|
|
|
// Use with stack BRDF (clear coat / coat)
|
|
real RoughnessToVariance(real roughness)
|
|
{
|
|
return 2.0 / Sq(roughness) - 2.0;
|
|
}
|
|
|
|
real VarianceToRoughness(real variance)
|
|
{
|
|
return sqrt(2.0 / (variance + 2.0));
|
|
}
|
|
|
|
float FilterPerceptualSmoothness(float perceptualSmoothness, float variance, float threshold)
|
|
{
|
|
float roughness = PerceptualSmoothnessToRoughness(perceptualSmoothness);
|
|
float squaredRoughness = saturate(roughness * roughness + min(2.0 * variance, threshold * threshold)); // threshold can be really low, square the value for easier control
|
|
|
|
return 1.0 - RoughnessToPerceptualRoughness(sqrt(squaredRoughness));
|
|
}
|
|
|
|
// Reference: Error Reduction and Simplification for Shading Anti-Aliasing
|
|
// Specular antialiasing for geometry-induced normal (and NDF) variations: Tokuyoshi / Kaplanyan et al.'s method.
|
|
// This is the deferred approximation, which works reasonably well so we keep it for forward too for now.
|
|
// screenSpaceVariance should be at most 0.5^2 = 0.25, as that corresponds to considering
|
|
// a gaussian pixel reconstruction kernel with a standard deviation of 0.5 of a pixel, thus 2 sigma covering the whole pixel.
|
|
float GeometricFilterVariance(float3 geometricNormalWS, float screenSpaceVariance)
|
|
{
|
|
float3 deltaU = ddx(geometricNormalWS);
|
|
float3 deltaV = ddy(geometricNormalWS);
|
|
|
|
return screenSpaceVariance * (dot(deltaU, deltaU) + dot(deltaV, deltaV));
|
|
}
|
|
|
|
float GeometricFilterPerceptualSmoothness(float perceptualSmoothness, float3 geometricNormalWS, float screenSpaceVariance, float threshold)
|
|
{
|
|
float variance = GeometricFilterVariance(geometricNormalWS, screenSpaceVariance);
|
|
return FilterPerceptualSmoothness(perceptualSmoothness, variance, threshold);
|
|
}
|
|
|
|
// Normal map filtering based on The Order : 1886 SIGGRAPH course notes implementation.
|
|
// Basically Toksvig with an intermediate single vMF lobe induced dispersion (Han et al. 2007)
|
|
//
|
|
// This returns 2 times the variance of the induced "mesoNDF" lobe (an NDF induced from a section of
|
|
// the normal map) from the level 0 mip normals covered by the "current texel".
|
|
//
|
|
// avgNormalLength gives the dispersion information for the covered normals.
|
|
//
|
|
// Note that hw filtering on the normal map should be trilinear to be conservative, while anisotropic
|
|
// risk underfiltering. Could also compute average normal on the fly with a proper normal map format,
|
|
// like Toksvig.
|
|
float TextureFilteringVariance(float avgNormalLength)
|
|
{
|
|
if (avgNormalLength < 1.0)
|
|
{
|
|
float avgNormLen2 = avgNormalLength * avgNormalLength;
|
|
float kappa = (3.0 * avgNormalLength - avgNormalLength * avgNormLen2) / (1.0 - avgNormLen2);
|
|
|
|
// Relationship between gaussian lobe and vMF lobe is 2 * variance = 1 / (2 * kappa) = roughness^2
|
|
// so to get variance we must use variance = 1 / (4 * kappa)
|
|
return 0.25 * kappa;
|
|
}
|
|
|
|
return 0.0f;
|
|
}
|
|
|
|
float TextureFilterPerceptualSmoothness(float perceptualSmoothness, float avgNormalLength, float threshold)
|
|
{
|
|
float variance = TextureFilteringVariance(avgNormalLength);
|
|
return FilterPerceptualSmoothness(perceptualSmoothness, variance, threshold);
|
|
}
|
|
|
|
// ----------------------------------------------------------------------------
|
|
// Helper for Disney parametrization
|
|
// ----------------------------------------------------------------------------
|
|
|
|
float3 ComputeDiffuseColor(float3 baseColor, float metallic)
|
|
{
|
|
return baseColor * (1.0 - metallic);
|
|
}
|
|
|
|
float3 ComputeFresnel0(float3 baseColor, float metallic, float dielectricF0)
|
|
{
|
|
return lerp(dielectricF0.xxx, baseColor, metallic);
|
|
}
|
|
|
|
// ----------------------------------------------------------------------------
|
|
// Helper for normal blending
|
|
// ----------------------------------------------------------------------------
|
|
|
|
// ref https://www.gamedev.net/topic/678043-how-to-blend-world-space-normals/#entry5287707
|
|
// assume compositing in world space
|
|
// Note: Using vtxNormal = real3(0, 0, 1) give the BlendNormalRNM formulation.
|
|
// TODO: Untested
|
|
real3 BlendNormalWorldspaceRNM(real3 n1, real3 n2, real3 vtxNormal)
|
|
{
|
|
// Build the shortest-arc quaternion
|
|
real4 q = real4(cross(vtxNormal, n2), dot(vtxNormal, n2) + 1.0) / sqrt(2.0 * (dot(vtxNormal, n2) + 1));
|
|
|
|
// Rotate the normal
|
|
return n1 * (q.w * q.w - dot(q.xyz, q.xyz)) + 2 * q.xyz * dot(q.xyz, n1) + 2 * q.w * cross(q.xyz, n1);
|
|
}
|
|
|
|
// ref http://blog.selfshadow.com/publications/blending-in-detail/
|
|
// ref https://gist.github.com/selfshadow/8048308
|
|
// Reoriented Normal Mapping
|
|
// Blending when n1 and n2 are already 'unpacked' and normalised
|
|
// assume compositing in tangent space
|
|
real3 BlendNormalRNM(real3 n1, real3 n2)
|
|
{
|
|
real3 t = n1.xyz + real3(0.0, 0.0, 1.0);
|
|
real3 u = n2.xyz * real3(-1.0, -1.0, 1.0);
|
|
real3 r = (t / t.z) * dot(t, u) - u;
|
|
return r;
|
|
}
|
|
|
|
// assume compositing in tangent space
|
|
real3 BlendNormal(real3 n1, real3 n2)
|
|
{
|
|
return normalize(real3(n1.xy * n2.z + n2.xy * n1.z, n1.z * n2.z));
|
|
}
|
|
|
|
// ----------------------------------------------------------------------------
|
|
// Helper for triplanar
|
|
// ----------------------------------------------------------------------------
|
|
|
|
// Ref: http://http.developer.nvidia.com/GPUGems3/gpugems3_ch01.html / http://www.slideshare.net/icastano/cascades-demo-secrets
|
|
real3 ComputeTriplanarWeights(real3 normal)
|
|
{
|
|
// Determine the blend weights for the 3 planar projections.
|
|
real3 blendWeights = abs(normal);
|
|
// Tighten up the blending zone
|
|
blendWeights = (blendWeights - 0.2);
|
|
blendWeights = blendWeights * blendWeights * blendWeights; // pow(blendWeights, 3);
|
|
// Force weights to sum to 1.0 (very important!)
|
|
blendWeights = max(blendWeights, real3(0.0, 0.0, 0.0));
|
|
blendWeights /= dot(blendWeights, 1.0);
|
|
|
|
return blendWeights;
|
|
}
|
|
|
|
// Planar/Triplanar convention for Unity in world space
|
|
void GetTriplanarCoordinate(float3 position, out float2 uvXZ, out float2 uvXY, out float2 uvZY)
|
|
{
|
|
// Caution: This must follow the same rule as what is use for SurfaceGradient triplanar
|
|
// TODO: Currently the normal mapping looks wrong without SURFACE_GRADIENT option because we don't handle corretly the tangent space
|
|
uvXZ = float2(position.z, position.x);
|
|
uvXY = float2(position.x, position.y);
|
|
uvZY = float2(position.z, position.y);
|
|
}
|
|
|
|
// ----------------------------------------------------------------------------
|
|
// Helper for detail map operation
|
|
// ----------------------------------------------------------------------------
|
|
|
|
real LerpWhiteTo(real b, real t)
|
|
{
|
|
real oneMinusT = 1.0 - t;
|
|
return oneMinusT + b * t;
|
|
}
|
|
|
|
real3 LerpWhiteTo(real3 b, real t)
|
|
{
|
|
real oneMinusT = 1.0 - t;
|
|
return real3(oneMinusT, oneMinusT, oneMinusT) + b * t;
|
|
}
|
|
|
|
#endif // UNITY_COMMON_MATERIAL_INCLUDED
|