material compiler: Precomputed V and H squared dots with tangents

Known bug: some of the emitters in staircase scene are black because they have normals wrong way around or vertex order inverted (so they are recognized as backfacing) and so NdotV is negative in irr_bsdf_cos_generate()

Author: Crisspl

include/irr/builtin/material_compiler/glsl/common.glsl

@@ -7,7 +7,6 @@
 	#error "You need to define 'vec3 irr_glsl_MC_getNormalizedWorldSpaceV()', 'vec3 irr_glsl_MC_getNormalizedWorldSpaceN()' , 'irr_glsl_MC_getWorldSpacePosition()', 'instr_t irr_glsl_MC_fetchInstr(in uint)', 'prefetch_instr_t irr_glsl_MC_fetchPrefetchInstr(in uint)', 'bsdf_data_t irr_glsl_MC_fetchBSDFData(in uint)' functions above"
 #endif
 
-#include <irr/builtin/glsl/bxdf/common.glsl>
 #include <irr/builtin/glsl/math/functions.glsl>
 #include <irr/builtin/glsl/format/decode.glsl>
 
@@ -201,28 +200,30 @@ bool op_isDiffuse(in uint op)
 #include <irr/builtin/glsl/bump_mapping/utils.glsl>
 
 //irr_glsl_BSDFAnisotropicParams currBSDFParams;
-irr_glsl_AnisotropicViewSurfaceInteraction currInteraction;
+MC_interaction_t currInteraction;
 reg_t registers[REG_COUNT];
 
 void updateLightSampleAfterNormalChange(inout irr_glsl_LightSample out_s)
 {
-	out_s.TdotL = dot(currInteraction.T, out_s.L);
-	out_s.BdotL = dot(currInteraction.B, out_s.L);
-	out_s.NdotL = dot(currInteraction.isotropic.N, out_s.L);
+	out_s.TdotL = dot(currInteraction.inner.T, out_s.L);
+	out_s.BdotL = dot(currInteraction.inner.B, out_s.L);
+	out_s.NdotL = dot(currInteraction.inner.isotropic.N, out_s.L);
 	out_s.NdotL2 = out_s.NdotL*out_s.NdotL;
 }
-void updateMicrofacetCacheAfterNormalChange(in irr_glsl_LightSample s, inout irr_glsl_AnisotropicMicrofacetCache out_microfacet)
+void updateMicrofacetCacheAfterNormalChange(in irr_glsl_LightSample s, inout MC_microfacet_t out_microfacet)
 {
 	const float NdotL = s.NdotL;
-	const float NdotV = currInteraction.isotropic.NdotV;
+	const float NdotV = currInteraction.inner.isotropic.NdotV;
 
 	const float LplusV_rcplen = inversesqrt(2.0 + 2.0 * s.VdotL);
 
-	out_microfacet.isotropic.NdotH = (NdotL + NdotV) * LplusV_rcplen;
-	out_microfacet.isotropic.NdotH2 = out_microfacet.isotropic.NdotH * out_microfacet.isotropic.NdotH;
+	out_microfacet.inner.isotropic.NdotH = (NdotL + NdotV) * LplusV_rcplen;
+	out_microfacet.inner.isotropic.NdotH2 = out_microfacet.inner.isotropic.NdotH * out_microfacet.inner.isotropic.NdotH;
+
+	out_microfacet.inner.TdotH = (currInteraction.inner.TdotV + s.TdotL) * LplusV_rcplen;
+	out_microfacet.inner.BdotH = (currInteraction.inner.BdotV + s.BdotL) * LplusV_rcplen;
 
-	out_microfacet.TdotH = (currInteraction.TdotV + s.TdotL) * LplusV_rcplen;
-	out_microfacet.BdotH = (currInteraction.BdotV + s.BdotL) * LplusV_rcplen;
+	finalizeMicrofacet(out_microfacet);
 }
 
 vec3 textureOrRGBconst(in uvec2 data, in bool texPresenceFlag)
@@ -341,7 +342,8 @@ mat2x4 instr_fetchSrcRegs(in instr_t i)
 void setCurrInteraction(in vec3 N, in vec3 V, in vec3 pos)
 {
 	irr_glsl_IsotropicViewSurfaceInteraction interaction = irr_glsl_calcFragmentShaderSurfaceInteractionFromViewVector(V, pos, N);
-	currInteraction = irr_glsl_calcAnisotropicInteraction(interaction);
+	currInteraction.inner = irr_glsl_calcAnisotropicInteraction(interaction);
+	finalizeInteraction(currInteraction);
 }
 void setCurrInteraction(in MC_precomputed_t precomp)
 {
@@ -387,7 +389,7 @@ bxdf_eval_t instr_execute_cos_eval_COATING(in instr_t instr, in mat2x4 srcs, in
 
 	// TODO include thickness_sigma in diffuse weight computation: exp(sigma_thickness * freePath)
 	// freePath = ( sqrt(refract_compute_NdotT2(NdotL2, rcpOrientedEta2)) + sqrt(refract_compute_NdotT2(NdotV2, rcpOrientedEta2)) )
-	vec3 fresnelNdotV = irr_glsl_fresnel_dielectric_frontface_only(eta, max(currInteraction.isotropic.NdotV, 0.0));
+	vec3 fresnelNdotV = irr_glsl_fresnel_dielectric_frontface_only(eta, max(currInteraction.inner.isotropic.NdotV, 0.0));
 	vec3 wd = irr_glsl_diffuseFresnelCorrectionFactor(eta, eta2) * (vec3(1.0) - fresnelNdotV) * (vec3(1.0) - irr_glsl_fresnel_dielectric_frontface_only(eta, s.NdotL));
 
 	bxdf_eval_t coat = srcs[0].xyz;
@@ -513,13 +515,13 @@ void runNormalPrecompStream(in instr_stream_t stream, in mat2 dUV, in MC_precomp
 		vec2 dh = readReg2(srcreg);
 
 		writeReg(dstreg,
-			irr_glsl_perturbNormal_derivativeMap(currInteraction.isotropic.N, dh, currInteraction.isotropic.V.dPosdScreen, dUV)
+			irr_glsl_perturbNormal_derivativeMap(currInteraction.inner.isotropic.N, dh, currInteraction.inner.isotropic.V.dPosdScreen, dUV)
 		);
 	}
 }
 
 #ifdef GEN_CHOICE_STREAM
-void instr_eval_and_pdf_execute(in instr_t instr, in MC_precomputed_t precomp, in irr_glsl_LightSample s, in irr_glsl_AnisotropicMicrofacetCache _microfacet, in bool skip)
+void instr_eval_and_pdf_execute(in instr_t instr, in MC_precomputed_t precomp, in irr_glsl_LightSample s, in MC_microfacet_t _microfacet, in bool skip)
 {
 	const uint op = instr_getOpcode(instr);
 	const bool is_bxdf = op_isBXDF(op);
@@ -533,7 +535,7 @@ void instr_eval_and_pdf_execute(in instr_t instr, in MC_precomputed_t precomp, i
 	bsdf_data_t bsdf_data;
 	mat2x3 ior;
 	mat2x3 ior2;
-	irr_glsl_AnisotropicMicrofacetCache microfacet;
+	MC_microfacet_t microfacet;
 
 	const bool run = !skip;
 
@@ -545,7 +547,7 @@ void instr_eval_and_pdf_execute(in instr_t instr, in MC_precomputed_t precomp, i
 		params = instr_getParameters(instr, bsdf_data);
 	}
 
-	const float NdotV = irr_glsl_conditionalAbsOrMax(is_bsdf, currInteraction.isotropic.NdotV, 0.0);
+	const float NdotV = irr_glsl_conditionalAbsOrMax(is_bsdf, currInteraction.inner.isotropic.NdotV, 0.0);
 
 	vec3 eval = vec3(0.0);
 	float pdf = 0.0;
@@ -584,29 +586,30 @@ void instr_eval_and_pdf_execute(in instr_t instr, in MC_precomputed_t precomp, i
 			bool is_valid = true;
 			bool refraction = false;
 #ifdef OP_DIELECTRIC
-			if (op == OP_DIELECTRIC && irr_glsl_isTransmissionPath(currInteraction.isotropic.NdotV, s.NdotL))
+			if (op == OP_DIELECTRIC && irr_glsl_isTransmissionPath(currInteraction.inner.isotropic.NdotV, s.NdotL))
 			{
-				irr_glsl_calcAnisotropicMicrofacetCache(microfacet, true, currInteraction.isotropic.V.dir, s.L, currInteraction.T, currInteraction.B, currInteraction.isotropic.N, s.NdotL, s.VdotL, eta, rcp_eta);
+				irr_glsl_calcAnisotropicMicrofacetCache(microfacet.inner, true, currInteraction.inner.isotropic.V.dir, s.L, currInteraction.inner.T, currInteraction.inner.B, currInteraction.inner.isotropic.N, s.NdotL, s.VdotL, eta, rcp_eta);
+				finalizeMicrofacet(microfacet);
 				refraction = true;
 			}
 			else
 #endif
 				microfacet = _microfacet;
 
 #if defined(OP_DIELECTRIC) || defined(OP_CONDUCTOR)
-			is_valid = irr_glsl_isValidVNDFMicrofacet(microfacet.isotropic, is_bsdf, refraction, s.VdotL, eta, rcp_eta);
+			is_valid = irr_glsl_isValidVNDFMicrofacet(microfacet.inner.isotropic, is_bsdf, refraction, s.VdotL, eta, rcp_eta);
 #endif
 
 			if (is_valid && a > ALPHA_EPSILON)
 			{
-				const float TdotV2 = currInteraction.TdotV * currInteraction.TdotV;
-				const float BdotV2 = currInteraction.BdotV * currInteraction.BdotV;
-				const float NdotV2 = currInteraction.isotropic.NdotV_squared;
+				const float TdotV2 = currInteraction.TdotV2;
+				const float BdotV2 = currInteraction.BdotV2;
+				const float NdotV2 = currInteraction.inner.isotropic.NdotV_squared;
 				const float NdotL2 = s.NdotL2;
 
-				const float TdotH2 = microfacet.TdotH * microfacet.TdotH;
-				const float BdotH2 = microfacet.BdotH * microfacet.BdotH;
-				const float NdotH2 = microfacet.isotropic.NdotH2;
+				const float TdotH2 = microfacet.TdotH2;
+				const float BdotH2 = microfacet.BdotH2;
+				const float NdotH2 = microfacet.inner.isotropic.NdotH2;
 
 				float G1_over_2NdotV = 0.0;
 				float G2_over_G1 = 0.0;
@@ -665,7 +668,7 @@ void instr_eval_and_pdf_execute(in instr_t instr, in MC_precomputed_t precomp, i
 				pdf = irr_glsl_smith_VNDF_pdf_wo_clamps(ndf_val, G1_over_2NdotV);
 				float remainder_scalar_part = G2_over_G1;
 
-				const float VdotH = is_bsdf ? microfacet.isotropic.VdotH : max(microfacet.isotropic.VdotH, 0.0);
+				const float VdotH = is_bsdf ? microfacet.inner.isotropic.VdotH : max(microfacet.inner.isotropic.VdotH, 0.0);
 				vec3 fr;
 #ifdef OP_CONDUCTOR
 				if (op == OP_CONDUCTOR)
@@ -679,8 +682,8 @@ void instr_eval_and_pdf_execute(in instr_t instr, in MC_precomputed_t precomp, i
 #ifndef NO_BSDF
 				if (is_bsdf)
 				{
-					float LdotH = microfacet.isotropic.LdotH;
-					float VdotHLdotH = microfacet.isotropic.VdotH * LdotH;
+					float LdotH = microfacet.inner.isotropic.LdotH;
+					float VdotHLdotH = microfacet.inner.isotropic.VdotH * LdotH;
 					LdotH = abs(LdotH);
 #ifdef NDF_GGX
 					if (ndf == NDF_GGX)
@@ -734,7 +737,7 @@ void instr_eval_and_pdf_execute(in instr_t instr, in MC_precomputed_t precomp, i
 		writeReg(REG_DST(regs), result);
 }
 
-eval_and_pdf_t irr_bsdf_eval_and_pdf(in MC_precomputed_t precomp, in instr_stream_t stream, in uint generator_offset, inout irr_glsl_LightSample s, inout irr_glsl_AnisotropicMicrofacetCache microfacet)
+eval_and_pdf_t irr_bsdf_eval_and_pdf(in MC_precomputed_t precomp, in instr_stream_t stream, in uint generator_offset, inout irr_glsl_LightSample s, inout MC_microfacet_t microfacet)
 {
 	setCurrInteraction(precomp);
 	for (uint i = 0u; i < stream.count; ++i)
@@ -775,7 +778,7 @@ eval_and_pdf_t irr_bsdf_eval_and_pdf(in MC_precomputed_t precomp, in instr_strea
 	return eval_and_pdf;
 }
 
-irr_glsl_LightSample irr_bsdf_cos_generate(in MC_precomputed_t precomp, in instr_stream_t stream, in vec3 rand, out vec3 out_remainder, out float out_pdf, out irr_glsl_AnisotropicMicrofacetCache out_microfacet, out uint out_gen_rnpOffset)
+irr_glsl_LightSample irr_bsdf_cos_generate(in MC_precomputed_t precomp, in instr_stream_t stream, in vec3 rand, out vec3 out_remainder, out float out_pdf, out MC_microfacet_t out_microfacet, out uint out_gen_rnpOffset)
 {
 	uint ix = 0u;
 	instr_t instr = irr_glsl_MC_fetchInstr(stream.offset);
@@ -803,7 +806,7 @@ irr_glsl_LightSample irr_bsdf_cos_generate(in MC_precomputed_t precomp, in instr
 #endif
 			{
 				vec3 eta = bsdf_data_decodeIoR(bsdf_data, OP_COATING)[0];
-				w_ = irr_glsl_fresnel_dielectric_frontface_only(eta, max(currInteraction.isotropic.NdotV, 0.0));
+				w_ = irr_glsl_fresnel_dielectric_frontface_only(eta, max(currInteraction.inner.isotropic.NdotV, 0.0));
 			}
 
 			float w = colorToScalar(w_);
@@ -854,22 +857,22 @@ irr_glsl_LightSample irr_bsdf_cos_generate(in MC_precomputed_t precomp, in instr
 	const bool is_bsdf = !op_isBRDF(op) && !is_coat;
 	const vec3 albedo = params_getReflectance(params);
 
-	const float NdotV = irr_glsl_conditionalAbsOrMax(is_bsdf, currInteraction.isotropic.NdotV, 0.0);
+	const float NdotV = irr_glsl_conditionalAbsOrMax(is_bsdf, currInteraction.inner.isotropic.NdotV, 0.0);
 	const bool positiveNdotV = (NdotV > FLT_MIN);
 
 	float localPdf = positiveNdotV ? 1.0 : 0.0;
 	vec3 rem = positiveNdotV ? vec3(1.0) : vec3(0.0);
 	uint ndf = instr_getNDF(instr);
 	irr_glsl_LightSample s;
 
-	const vec3 localV = irr_glsl_getTangentSpaceV(currInteraction);
-	const mat3 tangentFrame = irr_glsl_getTangentFrame(currInteraction);
+	const vec3 localV = irr_glsl_getTangentSpaceV(currInteraction.inner);
+	const mat3 tangentFrame = irr_glsl_getTangentFrame(currInteraction.inner);
 
 
 #ifdef OP_DELTATRANS
 	if (op == OP_DELTATRANS)
 	{
-		s = irr_glsl_createLightSample(-precomp.V, -1.0, currInteraction.T, currInteraction.B, currInteraction.isotropic.N);
+		s = irr_glsl_createLightSample(-precomp.V, -1.0, currInteraction.inner.T, currInteraction.inner.B, currInteraction.inner.isotropic.N);
 		// not computing microfacet cache since it's always transmission and it will be recomputed anyway
 		rem = vec3(1.0);
 		localPdf = irr_glsl_FLT_INF;
@@ -881,10 +884,11 @@ irr_glsl_LightSample irr_bsdf_cos_generate(in MC_precomputed_t precomp, in instr
 		const vec3 luminosityContributionHint = CIE_XYZ_Luma_Y_coeffs;
 		vec3 remMetadata;
 		s = irr_glsl_thin_smooth_dielectric_cos_generate_wo_clamps(
-			currInteraction.isotropic.V.dir, currInteraction.T, currInteraction.B, currInteraction.isotropic.N, 
-			currInteraction.isotropic.NdotV, NdotV, u, ior2[0], luminosityContributionHint, remMetadata
+			currInteraction.inner.isotropic.V.dir, currInteraction.inner.T, currInteraction.inner.B, currInteraction.inner.isotropic.N, 
+			currInteraction.inner.isotropic.NdotV, NdotV, u, ior2[0], luminosityContributionHint, remMetadata
 		);
-		out_microfacet = irr_glsl_calcAnisotropicMicrofacetCache(currInteraction, s);
+		out_microfacet.inner = irr_glsl_calcAnisotropicMicrofacetCache(currInteraction.inner, s);
+		finalizeMicrofacet(out_microfacet);
 		rem = irr_glsl_thin_smooth_dielectric_cos_remainder_and_pdf_wo_clamps(localPdf, remMetadata);
 	} else
 #endif
@@ -903,20 +907,21 @@ irr_glsl_LightSample irr_bsdf_cos_generate(in MC_precomputed_t precomp, in instr
 			}
 #endif
 			s = irr_glsl_createLightSampleTangentSpace(localV, localL, tangentFrame);
-			out_microfacet = irr_glsl_calcAnisotropicMicrofacetCache(currInteraction, s);
+			out_microfacet.inner = irr_glsl_calcAnisotropicMicrofacetCache(currInteraction.inner, s);
+			finalizeMicrofacet(out_microfacet);
 
-			rem *= albedo*irr_glsl_oren_nayar_cos_remainder_and_pdf(localPdf, s, currInteraction.isotropic, ax2);
+			rem *= albedo*irr_glsl_oren_nayar_cos_remainder_and_pdf(localPdf, s, currInteraction.inner.isotropic, ax2);
 			localPdf *= is_bsdf ? 0.5 : 1.0;
 		} else
 #endif
 #if defined(OP_CONDUCTOR) || defined(OP_DIELECTRIC)
 		if (op_hasSpecular(op))
 		{
-			const float TdotV2 = currInteraction.TdotV * currInteraction.TdotV;
-			const float BdotV2 = currInteraction.BdotV * currInteraction.BdotV;
-			const float NdotV2 = currInteraction.isotropic.NdotV_squared;
+			const float TdotV2 = currInteraction.inner.TdotV * currInteraction.inner.TdotV;
+			const float BdotV2 = currInteraction.inner.BdotV * currInteraction.inner.BdotV;
+			const float NdotV2 = currInteraction.inner.isotropic.NdotV_squared;
 
-			const vec3 upperHemisphereLocalV = currInteraction.isotropic.NdotV < 0.0 ? -localV : localV;
+			const vec3 upperHemisphereLocalV = currInteraction.inner.isotropic.NdotV < 0.0 ? -localV : localV;
 
 			float G2_over_G1 = 0.0;
 			float G1_over_2NdotV = 0.0;
@@ -973,12 +978,13 @@ irr_glsl_LightSample irr_bsdf_cos_generate(in MC_precomputed_t precomp, in instr
 			float eta = colorToScalar(ior[0]);
 			float rcpEta = 1.0/eta;
 
-			out_microfacet = irr_glsl_calcAnisotropicMicrofacetCache(refraction, localV, localH, localL, rcpEta, rcpEta*rcpEta);
+			out_microfacet.inner = irr_glsl_calcAnisotropicMicrofacetCache(refraction, localV, localH, localL, rcpEta, rcpEta*rcpEta);
 			s = irr_glsl_createLightSampleTangentSpace(localV, localL, tangentFrame);
 
-			const float TdotH2 = out_microfacet.TdotH * out_microfacet.TdotH;
-			const float BdotH2 = out_microfacet.BdotH * out_microfacet.BdotH;
-			const float NdotH2 = out_microfacet.isotropic.NdotH2;
+			finalizeMicrofacet(out_microfacet);
+			const float TdotH2 = out_microfacet.TdotH2;
+			const float BdotH2 = out_microfacet.BdotH2;
+			const float NdotH2 = out_microfacet.inner.isotropic.NdotH2;
 			const float NdotL = irr_glsl_conditionalAbsOrMax(is_bsdf, s.NdotL, 0.0);
 
 			BEGIN_CASES(ndf)
@@ -1014,7 +1020,7 @@ irr_glsl_LightSample irr_bsdf_cos_generate(in MC_precomputed_t precomp, in instr
 			{}
 			END_CASES
 
-			const float LdotH = out_microfacet.isotropic.LdotH;
+			const float LdotH = out_microfacet.inner.isotropic.LdotH;
 			const float VdotHLdotH = VdotH * LdotH;
 			// a trick, pdf was already multiplied by transmission/reflection choice probability above
 			const float reflectance = refraction ? 0.0 : 1.0;
@@ -1035,7 +1041,7 @@ vec3 runGenerateAndRemainderStream(in MC_precomputed_t precomp, in instr_stream_
 {
 	vec3 generator_rem;
 	float generator_pdf;
-	irr_glsl_AnisotropicMicrofacetCache microfacet;
+	MC_microfacet_t microfacet;
 	uint generator_rnpOffset;
 	irr_glsl_LightSample s = irr_bsdf_cos_generate(precomp, gcs, rand, generator_rem, generator_pdf, microfacet, generator_rnpOffset);
 	eval_and_pdf_t eval_pdf = irr_bsdf_eval_and_pdf(precomp, rnps, generator_rnpOffset, s, microfacet);

include/irr/builtin/material_compiler/glsl/common_declarations.glsl

@@ -3,6 +3,7 @@
 
 #include <irr/builtin/glsl/virtual_texturing/extensions.glsl>
 #include <irr/builtin/glsl/colorspace/encodeCIEXYZ.glsl>
+#include <irr/builtin/glsl/bxdf/common.glsl>
 
 #define instr_t uvec2
 #define prefetch_instr_t uvec4
@@ -36,6 +37,30 @@ struct MC_precomputed_t
 	bool frontface;
 };
 
+struct MC_microfacet_t
+{
+	irr_glsl_AnisotropicMicrofacetCache inner;
+	float TdotH2;
+	float BdotH2;
+};
+void finalizeMicrofacet(inout MC_microfacet_t mf)
+{
+	mf.TdotH2 = mf.inner.TdotH * mf.inner.TdotH;
+	mf.BdotH2 = mf.inner.BdotH * mf.inner.BdotH;
+}
+
+struct MC_interaction_t
+{
+	irr_glsl_AnisotropicViewSurfaceInteraction inner;
+	float TdotV2;
+	float BdotV2;
+};
+void finalizeInteraction(inout MC_interaction_t i)
+{
+	i.TdotV2 = i.inner.TdotV * i.inner.TdotV;
+	i.BdotV2 = i.inner.BdotV * i.inner.BdotV;
+}
+
 #define ALPHA_EPSILON 1.0e-08
 
 #define CIE_XYZ_Luma_Y_coeffs transpose(irr_glsl_sRGBtoXYZ)[1]