fixed a bug in beckmann remainder function

Author: devshgraphicsprogramming

examples_tests/46.SamplingValidation/fullscreen.frag

@@ -6,7 +6,7 @@
 #include <irr/builtin/glsl/bxdf/brdf/specular/ggx.glsl>
 #include <irr/builtin/glsl/bxdf/brdf/specular/beckmann.glsl>
 #include <irr/builtin/glsl/bxdf/bsdf/diffuse/lambert.glsl>
-#include <irr/builtin/glsl/bxdf/bsdf/specular/ggx.glsl>
+//#include <irr/builtin/glsl/bxdf/bsdf/specular/ggx.glsl>
 //#include <irr/builtin/glsl/bxdf/bsdf/specular/beckmann.glsl>
 
 layout (location = 0) out vec4 Color;
@@ -15,7 +15,7 @@ layout (push_constant) uniform PC {
     vec2 a;
     uint test;
 } pc;
-
+ 
 #define ETC_LAMBERT 0u
 #define ETC_GGX 1u
 #define ETC_BECKMANN 2u
@@ -36,7 +36,6 @@ void main()
     float pdf = 0.0;
     vec3 rem = vec3(0.0);
     vec3 brdf = vec3(0.0);
-    float multiplier = 0.5;
     if (pc.test==ETC_LAMBERT)
     {
         s = irr_glsl_lambertian_cos_generate(inter,u.xy);
@@ -56,28 +55,33 @@ void main()
         s = irr_glsl_beckmann_cos_generate(inter, u.xy, ax, ay, _cache);
         rem = irr_glsl_beckmann_aniso_cos_remainder_and_pdf(pdf, s, inter, _cache, ior, ax, ay);
         brdf = irr_glsl_beckmann_aniso_height_correlated_cos_eval(s, inter, _cache, ior, ax, ay);
+    /*
+        s = irr_glsl_beckmann_cos_generate(inter,u.xy,ax,ay,_cache);
+        rem = vec3(1.0);//4.0/inter.isotropic.NdotV);
+        pdf = irr_glsl_beckmann_pdf_wo_clamps(_cache.isotropic.NdotH2,max(inter.isotropic.NdotV,0.0),inter.isotropic.NdotV_squared,ax*ay);
+        brdf = vec3(pdf);
+        */
     }
     else if (pc.test==ETC_LAMBERT)
     {
         s = irr_glsl_lambertian_transmitter_cos_generate(inter,u);
         rem = vec3(irr_glsl_lambertian_cos_remainder_and_pdf(pdf, s));
         brdf = vec3(irr_glsl_lambertian_cos_eval(s));
-        multiplier = 0.25;
-    }
+    }/* cant do the tests properly :(, would need a 3D derivative and determinant
     else if (pc.test==ETC_GGX)
     {
         irr_glsl_AnisotropicMicrofacetCache _cache;
         s = irr_glsl_ggx_transmitter_cos_generate(inter, u.xy, ax, ay, _cache);
-        rem = irr_glsl_ggx_aniso_cos_remainder_and_pdf(pdf, s, inter, _cache, ior, ax, ay);
-        brdf = irr_glsl_ggx_height_correlated_aniso_cos_eval(s, inter, _cache, ior, ax, ay);
+        rem = irr_glsl_ggx_transmitter_aniso_cos_remainder_and_pdf(pdf, s, inter, _cache, ior[0].g, ax, ay);
+        brdf = irr_glsl_ggx_transmitter_height_correlated_aniso_cos_eval(s, inter, _cache, ior[0].g, ax, ay);
         multiplier = 0.25;
-    }/*
+    }
     else if (pc.test==ETC_BECKMANN)
     {
         irr_glsl_AnisotropicMicrofacetCache _cache;
         s = irr_glsl_beckmann_transmitter_cos_generate(inter, u.xy, ax, ay, _cache);
-        rem = irr_glsl_beckmann_aniso_cos_remainder_and_pdf(pdf, s, inter, _cache, ior, ax, ay);
-        brdf = irr_glsl_beckmann_aniso_height_correlated_cos_eval(s, inter, _cache, ior, ax, ay);
+        rem = irr_glsl_beckmann_aniso_cos_remainder_and_pdf(pdf, s, inter, _cache, ior[0].g, ax, ay);
+        brdf = irr_glsl_beckmann_aniso_height_correlated_cos_eval(s, inter, _cache, ior[0].g, ax, ay);
         multiplier = 0.25;
     }*/
 
@@ -90,6 +94,12 @@ void main()
     );
     float det = determinant(m);
 
-    Color = vec4(abs(rem*pdf-brdf),multiplier*abs(det*pdf/s.NdotL)); // preferred version of the test
-    //Color = vec4(multiplier*abs(det*pdf/s.NdotL),abs(rem*pdf-brdf));
+    const vec4 validColor = vec4(0.0,0.0,0.0,0.5); 
+    if (s.NdotL>0.0)
+    {
+        Color = vec4(abs(rem*pdf-brdf),abs(det*pdf/s.NdotL)*0.5); // preferred version of the test
+        //Color = vec4(abs(det*pdf/s.NdotL)*0.5,abs(rem*pdf-brdf));
+    }
+    else
+        Color = validColor;
 }

include/irr/builtin/glsl/bxdf/brdf/specular/beckmann.glsl

@@ -130,12 +130,12 @@ float irr_glsl_beckmann_pdf_wo_clamps(in float NdotH2, in float TdotH2, in float
 
 
 
-vec3 irr_glsl_beckmann_cos_remainder_and_pdf_wo_clamps(out float pdf, in float ndf, in float maxNdotL, in float NdotL2, in float maxNdotV, in float NdotV2, in vec3 reflectance, in float a2)
+vec3 irr_glsl_beckmann_cos_remainder_and_pdf_wo_clamps(out float pdf, in float ndf, in float NdotL2, in float maxNdotV, in float NdotV2, in vec3 reflectance, in float a2)
 {
     float onePlusLambda_V;
     pdf = irr_glsl_beckmann_pdf_wo_clamps(ndf,maxNdotV,NdotV2,a2,onePlusLambda_V);
 
-    float G2_over_G1 = irr_glsl_beckmann_smith_G2_over_G1(onePlusLambda_V, maxNdotL, NdotL2, a2);
+    float G2_over_G1 = irr_glsl_beckmann_smith_G2_over_G1(onePlusLambda_V, NdotL2, a2);
     return reflectance*G2_over_G1;
 }
 vec3 irr_glsl_beckmann_cos_remainder_and_pdf(out float pdf, in irr_glsl_LightSample _sample, in irr_glsl_IsotropicViewSurfaceInteraction interaction, in irr_glsl_IsotropicMicrofacetCache _cache, in mat2x3 ior, in float a2)
@@ -145,7 +145,7 @@ vec3 irr_glsl_beckmann_cos_remainder_and_pdf(out float pdf, in irr_glsl_LightSam
         const float ndf = irr_glsl_beckmann(a2, _cache.NdotH2);
         const vec3 reflectance = irr_glsl_fresnel_conductor(ior[0], ior[1], _cache.VdotH);
 
-        return irr_glsl_beckmann_cos_remainder_and_pdf_wo_clamps(pdf, ndf, _sample.NdotL, _sample.NdotL2, interaction.NdotV, interaction.NdotV_squared, reflectance, a2);
+        return irr_glsl_beckmann_cos_remainder_and_pdf_wo_clamps(pdf, ndf, _sample.NdotL2, interaction.NdotV, interaction.NdotV_squared, reflectance, a2);
     }
     else
     {
@@ -156,12 +156,12 @@ vec3 irr_glsl_beckmann_cos_remainder_and_pdf(out float pdf, in irr_glsl_LightSam
 
 
 
-vec3 irr_glsl_beckmann_aniso_cos_remainder_and_pdf_wo_clamps(out float pdf, in float ndf, in float maxNdotL, in float NdotL2, in float TdotL2, in float BdotL2, in float maxNdotV, in float TdotV2, in float BdotV2, in float NdotV2, in vec3 reflectance, in float ax2, in float ay2)
+vec3 irr_glsl_beckmann_aniso_cos_remainder_and_pdf_wo_clamps(out float pdf, in float ndf, in float NdotL2, in float TdotL2, in float BdotL2, in float maxNdotV, in float TdotV2, in float BdotV2, in float NdotV2, in vec3 reflectance, in float ax2, in float ay2)
 {
     float onePlusLambda_V;
     pdf = irr_glsl_beckmann_pdf_wo_clamps(ndf,maxNdotV,TdotV2,BdotV2,NdotV2,ax2,ay2,onePlusLambda_V);
 
-    float G2_over_G1 = irr_glsl_beckmann_smith_G2_over_G1(onePlusLambda_V, maxNdotL, TdotL2, BdotL2, NdotL2, ax2, ay2);
+    float G2_over_G1 = irr_glsl_beckmann_smith_G2_over_G1(onePlusLambda_V, TdotL2, BdotL2, NdotL2, ax2, ay2);
     return reflectance * G2_over_G1;
 }
 vec3 irr_glsl_beckmann_aniso_cos_remainder_and_pdf(out float pdf, in irr_glsl_LightSample _sample, in irr_glsl_AnisotropicViewSurfaceInteraction interaction, in irr_glsl_AnisotropicMicrofacetCache _cache, in mat2x3 ior, in float ax, in float ay)
@@ -182,7 +182,7 @@ vec3 irr_glsl_beckmann_aniso_cos_remainder_and_pdf(out float pdf, in irr_glsl_Li
         const float ndf = irr_glsl_beckmann(ax, ay, ax2, ay2, TdotH2, BdotH2, _cache.isotropic.NdotH2);
         const vec3 reflectance = irr_glsl_fresnel_conductor(ior[0], ior[1], _cache.isotropic.VdotH);
 
-	    return irr_glsl_beckmann_aniso_cos_remainder_and_pdf_wo_clamps(pdf, ndf, _sample.NdotL, _sample.NdotL2,TdotL2,BdotL2, interaction.isotropic.NdotV,TdotV2,BdotV2, interaction.isotropic.NdotV_squared, reflectance, ax2, ay2);
+	    return irr_glsl_beckmann_aniso_cos_remainder_and_pdf_wo_clamps(pdf, ndf, _sample.NdotL2,TdotL2,BdotL2, interaction.isotropic.NdotV,TdotV2,BdotV2, interaction.isotropic.NdotV_squared, reflectance, ax2, ay2);
     }
     else
     {

include/irr/builtin/glsl/bxdf/brdf/specular/ggx.glsl

@@ -141,41 +141,41 @@ float irr_glsl_ggx_pdf_wo_clamps(in float ndf, in float devsh_v, in float maxNdo
 }
 float irr_glsl_ggx_pdf_wo_clamps(in float NdotH2, in float maxNdotV, in float NdotV2, in float a2)
 {
-    float ndf = irr_glsl_ggx_trowbridge_reitz(a2, NdotH2);
-    float devsh_v = irr_glsl_smith_ggx_devsh_part(NdotV2, a2, 1.0-a2);
+    const float ndf = irr_glsl_ggx_trowbridge_reitz(a2, NdotH2);
+    const float devsh_v = irr_glsl_smith_ggx_devsh_part(NdotV2, a2, 1.0-a2);
 
     return irr_glsl_ggx_pdf_wo_clamps(ndf, devsh_v, maxNdotV);
 }
 
 float irr_glsl_ggx_pdf_wo_clamps(in float NdotH2, in float TdotH2, in float BdotH2, in float maxNdotV, in float NdotV2, in float TdotV2, in float BdotV2, in float ax, in float ay, in float ax2, in float ay2)
 {
-    float ndf = irr_glsl_ggx_aniso(TdotH2,BdotH2,NdotH2, ax, ay, ax2, ay2);
-    float devsh_v = irr_glsl_smith_ggx_devsh_part(TdotV2, BdotV2, NdotV2, ax2, ay2);
+    const float ndf = irr_glsl_ggx_aniso(TdotH2,BdotH2,NdotH2, ax, ay, ax2, ay2);
+    const float devsh_v = irr_glsl_smith_ggx_devsh_part(TdotV2, BdotV2, NdotV2, ax2, ay2);
 
     return irr_glsl_ggx_pdf_wo_clamps(ndf, devsh_v, maxNdotV);
 }
 
 
 
-vec3 irr_glsl_ggx_cos_remainder_and_pdf_wo_clamps(out float pdf, in float ndf, in float maxNdotL, in float NdotL2, in float maxNdotV, in float NdotV2, in float VdotH, in mat2x3 ior, in float a2)
+vec3 irr_glsl_ggx_cos_remainder_and_pdf_wo_clamps(out float pdf, in float ndf, in float maxNdotL, in float NdotL2, in float maxNdotV, in float NdotV2, in float VdotH, in vec3 reflectance, in float a2)
 {
     float one_minus_a2 = 1.0 - a2;
     float devsh_v = irr_glsl_smith_ggx_devsh_part(NdotV2, a2, one_minus_a2);
     pdf = irr_glsl_ggx_pdf_wo_clamps(ndf, devsh_v, maxNdotV);
 
     float G2_over_G1 = irr_glsl_ggx_smith_G2_over_G1_devsh(maxNdotL, NdotL2, maxNdotV, devsh_v, a2, one_minus_a2);
 
-    vec3 fr = irr_glsl_fresnel_conductor(ior[0], ior[1], VdotH);
-    return fr * G2_over_G1;
+    return reflectance * G2_over_G1;
 }
 
 vec3 irr_glsl_ggx_cos_remainder_and_pdf(out float pdf, in irr_glsl_LightSample _sample, in irr_glsl_IsotropicViewSurfaceInteraction interaction, in irr_glsl_IsotropicMicrofacetCache _cache, in mat2x3 ior, in float a2)
 {    
     if (_sample.NdotL>FLT_MIN && interaction.NdotV>FLT_MIN)
     {
         const float ndf = irr_glsl_ggx_trowbridge_reitz(a2, _cache.NdotH2);
+        const vec3 reflectance = irr_glsl_fresnel_conductor(ior[0], ior[1], _cache.VdotH);
 
-        return irr_glsl_ggx_cos_remainder_and_pdf_wo_clamps(pdf, ndf, max(_sample.NdotL,0.0), _sample.NdotL2, max(interaction.NdotV,0.0), interaction.NdotV_squared, _cache.VdotH, ior, a2);
+        return irr_glsl_ggx_cos_remainder_and_pdf_wo_clamps(pdf, ndf, max(_sample.NdotL,0.0), _sample.NdotL2, max(interaction.NdotV,0.0), interaction.NdotV_squared, _cache.VdotH, reflectance, a2);
     }
     else
     {
@@ -185,19 +185,18 @@ vec3 irr_glsl_ggx_cos_remainder_and_pdf(out float pdf, in irr_glsl_LightSample _
 }
 
 
-vec3 irr_glsl_ggx_aniso_cos_remainder_and_pdf_wo_clamps(out float pdf, in float ndf, in float maxNdotL, in float NdotL2, in float TdotL2, in float BdotL2, in float maxNdotV, in float TdotV2, in float BdotV2, in float NdotV2, in float VdotH, in mat2x3 ior, in float ax2,in float ay2)
+vec3 irr_glsl_ggx_aniso_cos_remainder_and_pdf_wo_clamps(out float pdf, in float ndf, in float maxNdotL, in float NdotL2, in float TdotL2, in float BdotL2, in float maxNdotV, in float TdotV2, in float BdotV2, in float NdotV2, in float VdotH, in vec3 reflectance, in float ax2,in float ay2)
 {
-    float devsh_v = irr_glsl_smith_ggx_devsh_part(TdotV2, BdotV2, NdotV2, ax2, ay2);
+    const float devsh_v = irr_glsl_smith_ggx_devsh_part(TdotV2, BdotV2, NdotV2, ax2, ay2);
     pdf = irr_glsl_ggx_pdf_wo_clamps(ndf, devsh_v, maxNdotV);
 
-    float G2_over_G1 = irr_glsl_ggx_smith_G2_over_G1_devsh(
+    const float G2_over_G1 = irr_glsl_ggx_smith_G2_over_G1_devsh(
         maxNdotL, TdotL2,BdotL2,NdotL2,
         maxNdotV, devsh_v,
         ax2, ay2
     );
 
-    vec3 fr = irr_glsl_fresnel_conductor(ior[0], ior[1], VdotH);
-    return fr * G2_over_G1;
+    return reflectance * G2_over_G1;
 }
 
 vec3 irr_glsl_ggx_aniso_cos_remainder_and_pdf(out float pdf, in irr_glsl_LightSample _sample, in irr_glsl_AnisotropicViewSurfaceInteraction interaction, in irr_glsl_AnisotropicMicrofacetCache _cache, in mat2x3 ior, in float ax, in float ay)
@@ -213,12 +212,12 @@ vec3 irr_glsl_ggx_aniso_cos_remainder_and_pdf(out float pdf, in irr_glsl_LightSa
         const float TdotV2 = interaction.TdotV*interaction.TdotV;
         const float BdotV2 = interaction.BdotV*interaction.BdotV;
 
-        float ax2 = ax*ax;
-        float ay2 = ay*ay;
-        float ndf = irr_glsl_ggx_aniso(TdotH2,BdotH2,_cache.isotropic.NdotH2, ax, ay, ax2, ay2);
-
-        // ggx doesn't need the special `if` guards because 
-	    return irr_glsl_ggx_aniso_cos_remainder_and_pdf_wo_clamps(pdf, ndf, max(_sample.NdotL, 0.0), _sample.NdotL2, TdotL2, BdotL2, max(interaction.isotropic.NdotV, 0.0), TdotV2, BdotV2, interaction.isotropic.NdotV_squared, _cache.isotropic.VdotH, ior, ax2, ay2);
+        const float ax2 = ax*ax;
+        const float ay2 = ay*ay;
+        const float ndf = irr_glsl_ggx_aniso(TdotH2,BdotH2,_cache.isotropic.NdotH2, ax, ay, ax2, ay2);
+        
+        const vec3 reflectance = irr_glsl_fresnel_conductor(ior[0], ior[1], _cache.isotropic.VdotH);
+	    return irr_glsl_ggx_aniso_cos_remainder_and_pdf_wo_clamps(pdf, ndf, max(_sample.NdotL, 0.0), _sample.NdotL2, TdotL2, BdotL2, max(interaction.isotropic.NdotV, 0.0), TdotV2, BdotV2, interaction.isotropic.NdotV_squared, _cache.isotropic.VdotH, reflectance, ax2, ay2);
     }
     else
     {

include/irr/builtin/glsl/bxdf/bsdf/specular/dielectric.glsl

@@ -35,6 +35,8 @@ irr_glsl_LightSample irr_glsl_thin_smooth_dielectric_cos_generate_wo_clamps(in v
     return smpl;
 }
 
+
+
 irr_glsl_LightSample irr_glsl_thin_smooth_dielectric_cos_generate_wo_clamps(in vec3 V, in vec3 N, in float NdotV, in float absNdotV, vec3 u, in vec3 eta2, in vec3 luminosityContributionHint)
 {
     vec3 dummy;
@@ -49,6 +51,7 @@ irr_glsl_LightSample irr_glsl_thin_smooth_dielectric_cos_generate(in irr_glsl_An
 }
 
 
+
 vec3 irr_glsl_thin_smooth_dielectric_cos_remainder_and_pdf_wo_clamps(out float pdf, in vec3 remainderMetadata)
 {
     pdf = 1.0 / 0.0; // should be reciprocal probability of the fresnel choice divided by 0.0, but would still be an INF.
@@ -74,6 +77,7 @@ vec3 irr_glsl_thin_smooth_dielectric_cos_remainder_and_pdf(out float pdf, in irr
 
 
 
+
 irr_glsl_LightSample irr_glsl_smooth_dielectric_cos_generate_wo_clamps(in vec3 V, in vec3 N, in bool backside, in float NdotV, in float absNdotV, in float NdotV2, vec3 u, in float rcpOrientedEta, in float orientedEta2, in float rcpOrientedEta2, out bool transmitted)
 {
     const float reflectance = irr_glsl_fresnel_dielectric_common(orientedEta2,absNdotV);