Accidentally staged half of the commits

source/VisTrace.cpp

@@ -810,6 +810,30 @@ LUA_FUNCTION(Material_Roughness)
 	return 0;
 }
 
+LUA_FUNCTION(Material_Anisotropy)
+{
+	LUA->CheckType(1, BSDFMaterial::id);
+	LUA->CheckType(2, Type::Number);
+
+	BSDFMaterial* pMat = LUA->GetUserType<BSDFMaterial>(1, BSDFMaterial::id);
+	// While anisotropy can be mapped -1 to 1
+	// with rotation it makes more sense to have it 0-1 (easily stored in a texture) and use rotation to change the direction
+	// This is also how blender's principled BSDF node does it
+	pMat->anisotropy = glm::clamp(LUA->GetNumber(2), 0., 1. - kMinGGXAlpha);
+	pMat->anisotropyOverriden = true;
+	return 0;
+}
+LUA_FUNCTION(Material_AnisotropicRotation)
+{
+	LUA->CheckType(1, BSDFMaterial::id);
+	LUA->CheckType(2, Type::Number);
+
+	BSDFMaterial* pMat = LUA->GetUserType<BSDFMaterial>(1, BSDFMaterial::id);
+	pMat->anisotropicRotation = glm::clamp(LUA->GetNumber(2), 0., 1.) * 2. * glm::pi<double>();
+	pMat->anisotropicRotationOverriden = true;
+	return 0;
+}
+
 LUA_FUNCTION(Material_IoR)
 {
 	LUA->CheckType(1, BSDFMaterial::id);
@@ -1516,6 +1540,8 @@ GMOD_MODULE_OPEN()
 
 		PUSH_C_FUNC(Material, Metalness);
 		PUSH_C_FUNC(Material, Roughness);
+		PUSH_C_FUNC(Material, Anisotropy);
+		PUSH_C_FUNC(Material, AnisotropicRotation);
 
 		PUSH_C_FUNC(Material, IoR);
 

source/libraries/BSDF.cpp

@@ -1,12 +1,11 @@
 #include "BSDF.h"
 
 #include "glm/ext/scalar_constants.hpp"
+#include "glm/gtx/rotate_vector.hpp"
 
 using namespace glm;
 using namespace VisTrace;
 
-static const float kMinGGXAlpha = 0.0064f;
-
 int BSDFMaterial::id = -1;
 
 void BSDFMaterial::PrepShadingData(const vec3& hitColour, float hitMetalness, float hitRoughness)
@@ -801,13 +800,13 @@ bool SampleSpecularTransmission(
 }
 #pragma endregion
 
-inline vec3 to_local(const vec3& T, const vec3& B, const vec3& N, const vec3& v)
+inline vec3 to_local(const BSDFMaterial& data, const vec3& T, const vec3& B, const vec3& N, const vec3& v)
 {
-	return vec3(dot(v, T), dot(v, B), dot(v, N));
+	return vec3(dot(v, rotate(T, data.anisotropicRotation, N)), dot(v, rotate(B, data.anisotropicRotation, N)), dot(v, N));
 }
-inline vec3 from_local(const vec3& T, const vec3& B, const vec3& N, const vec3& v)
+inline vec3 from_local(const BSDFMaterial& data, const vec3& T, const vec3& B, const vec3& N, const vec3& v)
 {
-	return T * v.x + B * v.y + N * v.z;
+	return rotate(T, data.anisotropicRotation, N) * v.x + rotate(B, data.anisotropicRotation, N) * v.y + N * v.z;
 }
 
 bool SampleBSDF(
@@ -823,7 +822,7 @@ bool SampleBSDF(
 	float lobeSelect = sg->GetFloat();
 
 	const bool entering = dot(incidentWorld, normal) >= 0.f;
-	const vec3 incident = entering ? to_local(tangent, binormal, normal, incidentWorld) : to_local(-tangent, -binormal, -normal, incidentWorld);
+	const vec3 incident = entering ? to_local(data, tangent, binormal, normal, incidentWorld) : to_local(data, -tangent, -binormal, -normal, incidentWorld);
 
 	if (lobeSelect < pDiffuse) {
 		if (!SampleDiffuse(data, incident, sg, result.lobe, result.scattered, result.weight, result.pdf)) return false;
@@ -863,7 +862,7 @@ bool SampleBSDF(
 		if (pSpecTrans > 0.f) result.pdf += pSpecTrans * EvalSpecularTransmissionPDF(data, incident, result.scattered, entering);
 	}
 
-	result.scattered = entering ? from_local(tangent, binormal, normal, result.scattered) : from_local(-tangent, -binormal, -normal, result.scattered);
+	result.scattered = entering ? from_local(data, tangent, binormal, normal, result.scattered) : from_local(data, -tangent, -binormal, -normal, result.scattered);
 	return true;
 }
 
@@ -878,11 +877,11 @@ vec3 EvalBSDF(
 
 	const bool entering = dot(incidentWorld, normal) >= 0.f;
 	const vec3 incident = entering ?
-		to_local(tangent, binormal, normal, incidentWorld) :
-		to_local(-tangent, -binormal, -normal, incidentWorld);
+		to_local(data, tangent, binormal, normal, incidentWorld) :
+		to_local(data, -tangent, -binormal, -normal, incidentWorld);
 	const vec3 scattered = entering ?
-		to_local(tangent, binormal, normal, scatteredWorld) :
-		to_local(-tangent, -binormal, -normal, scatteredWorld);
+		to_local(data, tangent, binormal, normal, scatteredWorld) :
+		to_local(data, -tangent, -binormal, -normal, scatteredWorld);
 
 	vec3 result{ 0, 0, 0 };
 	if (pDiffuse > 0.f)
@@ -909,11 +908,11 @@ float EvalPDF(
 
 	const bool entering = dot(incidentWorld, normal) >= 0.f;
 	const vec3 incident = entering ?
-		to_local(tangent, binormal, normal, incidentWorld) :
-		to_local(-tangent, -binormal, -normal, incidentWorld);
+		to_local(data, tangent, binormal, normal, incidentWorld) :
+		to_local(data, -tangent, -binormal, -normal, incidentWorld);
 	const vec3 scattered = entering ?
-		to_local(tangent, binormal, normal, scatteredWorld) :
-		to_local(-tangent, -binormal, -normal, scatteredWorld);
+		to_local(data, tangent, binormal, normal, scatteredWorld) :
+		to_local(data, -tangent, -binormal, -normal, scatteredWorld);
 
 	float pdf = 0.f;
 	if (pDiffuse > 0.f)

source/libraries/BSDF.h

@@ -4,6 +4,8 @@
 
 #include "vistrace/ISampler.h"
 
+constexpr float kMinGGXAlpha = 0.0064f;
+
 // Most significant bit of each nibble reserved 
 enum class LobeType : uint8_t
 {
@@ -78,6 +80,8 @@ struct BSDFMaterial
 
 	bool anisotropyOverriden = false;
 	float anisotropy = 0.f;
+	bool anisotropicRotationOverriden = false;
+	float anisotropicRotation = 0.f;
 
 	float diffuseTransmission = 0.f;
 	float specularTransmission = 0.f;