nbl_glsl_ compute interaction functions iwth user-provided pos derivatives

Author: Crisspl

examples_tests/22.RaytracedAO/raygen.comp

@@ -14,10 +14,6 @@ layout(set = 2, binding = 4) uniform sampler2D encodedNormal;
 layout(set = 2, binding = 5) uniform sampler2D uvCoords;
 
 
-// for materials
-// dummies needed because of the functions for fragment shader surface intersections
-vec3 dFdx(in vec3 r) {return vec3(0.0/0.0);}
-vec3 dFdy(in vec3 r) {return vec3(0.0/0.0);}
 // no idea yet
 #define sizeof_bsdf_data 1u // wtf??? it's not supposed to be user-defined
 #include <nbl/builtin/glsl/material_compiler/common_declarations.glsl>
@@ -32,10 +28,14 @@ vec3 nbl_glsl_MC_getNormalizedWorldSpaceN()
 	return normalizedN;
 }
 vec3 worldPosition;
-vec3 nbl_glsl_MC_WorldSpacePosition()
+vec3 nbl_glsl_MC_getWorldSpacePosition()
 {
 	return worldPosition;
 }
+mat2x3 nbl_glsl_MC_getdPos(in vec3 p)
+{
+	return mat2x3(vec3(0.0/0.0), vec3(0.0/0.0));
+}
 /*
 #define _IRR_USER_PROVIDED_MATERIAL_COMPILER_GLSL_BACKEND_FUNCTIONS_
 instr_stream_t getEvalStream(in MC_precomputed_t precomp)

include/nbl/builtin/glsl/bxdf/common.glsl

@@ -134,13 +134,12 @@ mat2x4 nbl_glsl_applyScreenSpaceChainRule4D3(in mat3x4 dFdG, in mat2x3 dGdScreen
    return dFdG*dGdScreen;
 }
 
-// only in the fragment shader we have access to implicit derivatives
-nbl_glsl_IsotropicViewSurfaceInteraction nbl_glsl_calcFragmentShaderSurfaceInteractionFromViewVector(in vec3 _View, in vec3 _SurfacePos, in vec3 _Normal)
+nbl_glsl_IsotropicViewSurfaceInteraction nbl_glsl_calcSurfaceInteractionFromViewVector(in vec3 _View, in vec3 _SurfacePos, in vec3 _Normal, in mat2x3 dpd_)
 {
     nbl_glsl_IsotropicViewSurfaceInteraction interaction;
     interaction.V.dir = _View;
-    interaction.V.dPosdScreen[0] = dFdx(_SurfacePos);// TODO: require the user to feed us the derivatives
-    interaction.V.dPosdScreen[1] = dFdy(_SurfacePos);
+    interaction.V.dPosdScreen[0] = dpd_[0];
+    interaction.V.dPosdScreen[1] = dpd_[1];
     interaction.N = _Normal;
     float invlenV2 = inversesqrt(dot(interaction.V.dir, interaction.V.dir));
     float invlenN2 = inversesqrt(dot(interaction.N, interaction.N));
@@ -150,6 +149,18 @@ nbl_glsl_IsotropicViewSurfaceInteraction nbl_glsl_calcFragmentShaderSurfaceInter
     interaction.NdotV_squared = interaction.NdotV * interaction.NdotV;
     return interaction;
 }
+nbl_glsl_IsotropicViewSurfaceInteraction nbl_glsl_calcSurfaceInteraction(in vec3 _CamPos, in vec3 _SurfacePos, in vec3 _Normal, in mat2x3 dpd_)
+{
+    vec3 V = _CamPos - _SurfacePos;
+    return nbl_glsl_calcSurfaceInteractionFromViewVector(V, _SurfacePos, _Normal, dpd_);
+}
+
+// only in the fragment shader we have access to implicit derivatives
+nbl_glsl_IsotropicViewSurfaceInteraction nbl_glsl_calcFragmentShaderSurfaceInteractionFromViewVector(in vec3 _View, in vec3 _SurfacePos, in vec3 _Normal)
+{
+    mat2x3 dpd = mat2x3(dFdx(_SurfacePos), dFdy(_SurfacePos));
+    return nbl_glsl_calcSurfaceInteractionFromViewVector(_View, _SurfacePos, _Normal, dpd);
+}
 nbl_glsl_IsotropicViewSurfaceInteraction nbl_glsl_calcFragmentShaderSurfaceInteraction(in vec3 _CamPos, in vec3 _SurfacePos, in vec3 _Normal)
 {
     vec3 V = _CamPos - _SurfacePos;

include/nbl/builtin/glsl/material_compiler/common.glsl

@@ -4,7 +4,7 @@
 #include <nbl/builtin/glsl/material_compiler/common_declarations.glsl>
 
 #ifndef _NBL_USER_PROVIDED_MATERIAL_COMPILER_GLSL_BACKEND_FUNCTIONS_
-	#error "You need to define 'vec3 nbl_glsl_MC_getNormalizedWorldSpaceV()', 'vec3 nbl_glsl_MC_getNormalizedWorldSpaceN()' , 'nbl_glsl_MC_getWorldSpacePosition()', 'nbl_glsl_instr_t nbl_glsl_MC_fetchInstr(in uint)', 'nbl_glsl_prefetch_instr_t nbl_glsl_MC_fetchPrefetchInstr(in uint)', 'nbl_glsl_bsdf_data_t nbl_glsl_MC_fetchBSDFData(in uint)' functions above"
+	#error "You need to define 'vec3 nbl_glsl_MC_getNormalizedWorldSpaceV()', 'vec3 nbl_glsl_MC_getNormalizedWorldSpaceN()' , 'nbl_glsl_MC_getWorldSpacePosition()', 'nbl_glsl_instr_t nbl_glsl_MC_fetchInstr(in uint)', 'nbl_glsl_prefetch_instr_t nbl_glsl_MC_fetchPrefetchInstr(in uint)', 'nbl_glsl_bsdf_data_t nbl_glsl_MC_fetchBSDFData(in uint)', 'mat2x3 nbl_glsl_MC_getdPos(in vec3 p)' functions above"
 #endif
 
 #include <nbl/builtin/glsl/math/functions.glsl>
@@ -341,7 +341,8 @@ mat2x4 nbl_glsl_instr_fetchSrcRegs(in nbl_glsl_instr_t i)
 
 void nbl_glsl_setCurrInteraction(in vec3 N, in vec3 V, in vec3 pos)
 {
-	nbl_glsl_IsotropicViewSurfaceInteraction interaction = nbl_glsl_calcFragmentShaderSurfaceInteractionFromViewVector(V, pos, N);
+	mat2x3 dp = nbl_glsl_MC_getdPos(pos);
+	nbl_glsl_IsotropicViewSurfaceInteraction interaction = nbl_glsl_calcSurfaceInteractionFromViewVector(V, pos, N, dp);
 	currInteraction.inner = nbl_glsl_calcAnisotropicInteraction(interaction);
 	nbl_glsl_finalizeInteraction(currInteraction);
 }

src/nbl/ext/MitsubaLoader/CMitsubaLoader.cpp

@@ -180,6 +180,10 @@ nbl_glsl_bsdf_data_t nbl_glsl_MC_fetchBSDFData(in uint ix)
 {
 	return bsdf_buf.data[ix];
 }
+mat2x3 nbl_glsl_MC_getdPos(in vec3 p)
+{
+	return mat2x3(dFdx(p), dFdy(p));
+}
 #define _NBL_USER_PROVIDED_MATERIAL_COMPILER_GLSL_BACKEND_FUNCTIONS_
 )";
 _NBL_STATIC_INLINE_CONSTEXPR const char* FRAGMENT_SHADER_IMPL = R"(