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#ifndef UNITY_COMMON_MATERIAL_INCLUDED
#define UNITY_COMMON_MATERIAL_INCLUDED
//-----------------------------------------------------------------------------
// Helper function for anisotropy
//-----------------------------------------------------------------------------
void ConvertAnisotropyToRoughness(float roughness, float anisotropy, out float roughnessT, out float roughnessB)
{
// Use the parametrization of Sony Imageworks.
// Ref: Revisiting Physically Based Shading at Imageworks, p. 15.
roughnessT = roughness * (1 + anisotropy);
roughnessB = roughness * (1 - anisotropy);
}
//-----------------------------------------------------------------------------
// Helper function for perceptual roughness
//-----------------------------------------------------------------------------
float PerceptualRoughnessToRoughness(float perceptualRoughness)
{
return perceptualRoughness * perceptualRoughness;
}
float RoughnessToPerceptualRoughness(float roughness)
{
return sqrt(roughness);
}
float PerceptualSmoothnessToRoughness(float perceptualSmoothness)
{
return (1.0 - perceptualSmoothness) * (1.0 - perceptualSmoothness);
}
float PerceptualSmoothnessToPerceptualRoughness(float perceptualSmoothness)
{
return (1.0 - perceptualSmoothness);
}
// ----------------------------------------------------------------------------
// Parallax mapping
// ----------------------------------------------------------------------------
// ref https://www.gamedev.net/topic/678043-how-to-blend-world-space-normals/#entry5287707
// assume compositing in world space
// Note: Using vtxNormal = float3(0, 0, 1) give the BlendNormalRNM formulation.
// TODO: Untested
float3 BlendNormalWorldspaceRNM(float3 n1, float3 n2, float3 vtxNormal)
{
// Build the shortest-arc quaternion
float4 q = float4(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
float3 BlendNormalRNM(float3 n1, float3 n2)
{
float3 t = n1.xyz + float3(0.0, 0.0, 1.0);
float3 u = n2.xyz * float3(-1.0, -1.0, 1.0);
float3 r = (t / t.z) * dot(t, u) - u;
return r;
}
// assume compositing in tangent space
float3 BlendNormal(float3 n1, float3 n2)
{
return normalize(float3(n1.xy * n2.z + n2.xy * n1.z, n1.z * n2.z));
}
// Ref: http://http.developer.nvidia.com/GPUGems3/gpugems3_ch01.html / http://www.slideshare.net/icastano/cascades-demo-secrets
float3 ComputeTriplanarWeights(float3 normal)
{
// Determine the blend weights for the 3 planar projections.
float3 blendWeights = abs(normal);
// Tighten up the blending zone
blendWeights = (blendWeights - 0.2) * 7.0;
blendWeights = blendWeights * blendWeights * blendWeights; // pow(blendWeights, 3);
// Force weights to sum to 1.0 (very important!)
blendWeights = max(blendWeights, float3(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);
}
float LerpWhiteTo(float b, float t)
{
float oneMinusT = 1.0 - t;
return oneMinusT + b * t;
}
float3 LerpWhiteTo(float3 b, float t)
{
float oneMinusT = 1.0 - t;
return float3(oneMinusT, oneMinusT, oneMinusT) + b * t;
}
// ----------------------------------------------------------------------------
// SSS/Transmittance
// ----------------------------------------------------------------------------
// Computes the fraction of light passing through the object.
// Evaluate Int{0, inf}{2 * Pi * r * R(sqrt(r^2 + d^2))}, where R is the diffusion profile.
// Note: 'volumeAlbedo' should be premultiplied by 0.25.
// Ref: Approximate Reflectance Profiles for Efficient Subsurface Scattering by Pixar (BSSRDF only).
float3 ComputeTransmittanceDisney(float3 S, float3 volumeAlbedo, float thickness, float radiusScale)
{
// Thickness and SSS radius are decoupled for artists.
// In theory, we should modify the thickness by the inverse of the radius scale of the profile.
// thickness /= radiusScale;
#if 0
float3 expOneThird = exp(((-1.0 / 3.0) * thickness) * S);
#else
// Help the compiler.
float k = (-1.0 / 3.0) * LOG2_E;
float3 p = (k * thickness) * S;
float3 expOneThird = exp2(p);
#endif
// Premultiply & optimize: T = (1/4 * A) * (e^(-t * S) + 3 * e^(-1/3 * t * S))
return volumeAlbedo * (expOneThird * expOneThird * expOneThird + 3 * expOneThird);
}
// Evaluates transmittance for a linear combination of two normalized 2D Gaussians.
// Ref: Real-Time Realistic Skin Translucency (2010), equation 9 (modified).
// Note: 'volumeAlbedo' should be premultiplied by 0.25, correspondingly 'lerpWeight' by 4,
// and 'halfRcpVariance1' should be prescaled by (0.1 * SssConstants.SSS_BASIC_DISTANCE_SCALE)^2.
float3 ComputeTransmittanceJimenez(float3 halfRcpVariance1, float lerpWeight1,
float3 halfRcpVariance2, float lerpWeight2,
float3 volumeAlbedo, float thickness, float radiusScale)
{
// Thickness and SSS radius are decoupled for artists.
// In theory, we should modify the thickness by the inverse of the radius scale of the profile.
// thickness /= radiusScale;
float t2 = thickness * thickness;
// T = A * lerp(exp(-t2 * halfRcpVariance1), exp(-t2 * halfRcpVariance2), lerpWeight2)
return volumeAlbedo * (exp(-t2 * halfRcpVariance1) * lerpWeight1 + exp(-t2 * halfRcpVariance2) * lerpWeight2);
}
// Ref: Steve McAuley - Energy-Conserving Wrapped Diffuse
float ComputeWrappedDiffuseLighting(float NdotL, float w)
{
return saturate((NdotL + w) / ((1 + w) * (1 + w)));
}
// In order to support subsurface scattering, we need to know which pixels have an SSS material.
// It can be accomplished by reading the stencil buffer.
// A faster solution (which avoids an extra texture fetch) is to simply make sure that
// all pixels which belong to an SSS material are not black (those that don't always are).
float3 TagLightingForSSS(float3 subsurfaceLighting)
{
subsurfaceLighting.r = max(subsurfaceLighting.r, HFLT_MIN);
return subsurfaceLighting;
}
// See TagLightingForSSS() for details.
bool TestLightingForSSS(float3 subsurfaceLighting)
{
return subsurfaceLighting.r > 0;
}
// MACRO from Legacy Untiy
// Transforms 2D UV by scale/bias property
#define TRANSFORM_TEX(tex, name) ((tex.xy) * name##_ST.xy + name##_ST.zw)
#define GET_TEXELSIZE_NAME(name) (name##_TexelSize)
#endif // UNITY_COMMON_MATERIAL_INCLUDED