BRDF explorer app: Some progress on generating shaders

examples_tests/13.BRDF_Explorer/BRDFExplorerApp.cpp

@@ -142,38 +142,48 @@ class CShaderManager
     video::E_MATERIAL_TYPE addShader(const SParams& _params)
     {
         std::string source =
-R"(#version 430 core
+            R"(#version 430 core
 
 layout (location = 0) out vec4 OutColor;
 
 in vec3 WorldPos;
 in vec2 TexCoords;
 in vec3 Normal;
 
-layout (location = 0)  uniform vec3 uEmissive;
-layout (location = 1)  uniform vec3 uAlbedo;
-layout (location = 2)  uniform float uRoughness1;
-layout (location = 3)  uniform float uRoughness2;
-layout (location = 4)  uniform float uIoR;
-layout (location = 5)  uniform float uMetallic;
-layout (location = 6)  uniform float uHeightFactor;
-layout (location = 7)  uniform vec3 uLightColor;
-layout (location = 8)  uniform vec3 uLightPos;
-layout (location = 9)  uniform sampler2D uAlbedoMap;
-layout (location = 10) uniform sampler2D uRoughnessMap;
-layout (location = 11) uniform sampler2D uIoRMap;
-layout (location = 12) uniform sampler2D uMetallicMap;
-layout (location = 13) uniform sampler2D uBumpMap;
-layout (location = 14) uniform sampler2D uAOMap;
+layout (location = 0) uniform vec3 uEmissive;
+layout (location = 1) uniform vec3 uAlbedo;
+layout (location = 2) uniform float uRoughness1;
+layout (location = 3) uniform float uRoughness2;
+layout (location = 4) uniform float uIoR;
+layout (location = 5) uniform float uMetallic;
+layout (location = 6) uniform float uHeightFactor;
+layout (location = 7) uniform vec3 uLightColor;
+layout (location = 8) uniform vec3 uLightPos;
+layout (binding = 0) uniform sampler2D uAlbedoMap;
+layout (binding = 1) uniform sampler2D uRoughnessMap;
+layout (binding = 2) uniform sampler2D uIoRMap;
+layout (binding = 3) uniform sampler2D uMetallicMap;
+layout (binding = 4) uniform sampler2D uBumpMap;
+layout (binding = 5) uniform sampler2D uAOMap;
 
 float getRoughness();
 float getMetallic();
 float getIoR();
 float getAO();
 vec3 getAlbedo();
-
-float diffuse(...);
-float specular(...);
+)"
++
+IncludeHandler->getIncludeStandard("irr/builtin/glsl/brdf/diffuse/oren_nayar.glsl")
++
+IncludeHandler->getIncludeStandard("irr/builtin/glsl/brdf/specular/ndf/ggx_trowbridge_reitz.glsl")
++
+IncludeHandler->getIncludeStandard("irr/builtin/glsl/brdf/specular/geom/ggx_smith.glsl")
++
+IncludeHandler->getIncludeStandard("irr/builtin/glsl/brdf/specular/fresnel/fresnel_schlick.glsl")
++
+R"(
+float diffuse(in float a2, in vec3 N, in vec3 L, in vec3 V, in float NdotL, in float NdotV);
+float specular(in float a2, in float NdotL, in float NdotV, in float NdotH);
 
 void main() {
     const vec3 N = normalize(Normal);
@@ -193,36 +203,36 @@ void main() {
     const vec3 albedo = getAlbedo();
     const float ior = getIoR();
     const float ao = getAO();
-    const float F0 = mix(vec3(ior, ior, ior), albedo, metallic);
+    const vec3 F0 = mix(vec3(1.0-ior), albedo, metallic);
     const vec3 fresnel = FresnelSchlick(F0, NdotV);
 
-    float diffuse = diffuse(...) * (1.0 - metallic);
-    float spec = specular(...);
+    float diffuse = diffuse(a2, N, L, V, NdotL, NdotV) * (1.0 - metallic);
+    float spec = specular(a2, NdotL, NdotV, NdotH);
 
     vec3 color = ((diffuse * albedo * (vec3(1.0) - fresnel)) + (spec * fresnel)) * uLightColor / dot(relLightPos, relLightPos);
-    // color *= NdotL; // ???
     OutColor = vec4(color, 1.0);
 }
 )";
         source += genGetters(_params);
 
-        source += "float diffuse(...) {\n";
+        source += "float diffuse(in float a2, in vec3 N, in vec3 L, in vec3 V, in float NdotL, in float NdotV) {\n";
         if (_params.constantMetallic && !_params.metallicIsOne)
         {
-            if (_params.constantRoughness && !_params.roughnessIsZero)
-                source += "\treturn lambert(...);";
+            if (_params.constantRoughness && _params.roughnessIsZero)
+                source += "\treturn NdotL;";
             else
-                source += "\treturn orey_nayar(...);";
+                source += "\treturn oren_nayar(a2, N, L, V, NdotL, NdotV);";
         }
         else source += "\treturn 0.0;";
         source += "\n}\n";
         source += 
-R"(float specular(...) {
+R"(float specular(in float a2, in float NdotL, in float NdotV, in float NdotH) {
     float ndf = GGXTrowbridgeReitz(a2, NdotH);
-    float geom = GGXSmith(a2, NdotV);
+    float geom = GGXSmith(a2, NdotL, NdotV);
 
     return ndf*geom / (4.0 * NdotV * NdotL);
-})";
+}
+)";
 
         return Shaders.insert({flagsToKey(_params), video::EMT_SOLID}).first->second; // TODO
     }

examples_tests/13.BRDF_Explorer/CBRDFBuiltinIncludeLoader.h

@@ -8,16 +8,90 @@ class CBRDFBuiltinIncludeLoader : public irr::asset::IBuiltinIncludeLoader
 public:
     const char* getVirtualDirectoryName() const override { return "glsl/brdf/"; }
 
+private:
+    static std::string getOrenNayar(const std::string&)
+    {
+        return
+R"(#ifndef _BRDF_DIFFUSE_OREN_NAYAR_INCLUDED_
+#define _BRDF_DIFFUSE_OREN_NAYAR_INCLUDED_
+
+float oren_nayar(in float a2, in vec3 N, in vec3 L, in vec3 V, in float NdotL, in float NdotV)
+{
+    // theta - polar angles
+    // phi - azimuth angles
+    vec2 AB = vec2(1.0, 0.0) + vec2(-0.5, 0.45) * vec2(a2, a2)/vec2(a2+0.33, a2+0.09);
+    vec2 cos_theta = vec2(NdotL, NdotV);
+    vec2 cos_theta2 = cos_theta*cos_theta;
+    float sin_theta = sqrt((1.0 - cos_theta2.x) * (1.0 - cos_theta2.y)); //this is actually equal to sqrt(sin(theta_i) * sin(theta_r))
+    float C = sin_theta / max(cos_theta.x, cos_theta.y);
+    
+    vec3 light_plane = normalize(L - cos_theta.x*N);
+    vec3 view_plane = normalize(V - cos_theta.y*N);
+    float cos_phi = max(0.0, dot(light_plane, view_plane));//not sure about this
+
+    return cos_theta.x * (AB.x + AB.y * cos_phi * C) / 3.14159265359;
+}
+
+#endif
+)";
+    }
+    static std::string getGGXTrowbridgeReitz(const std::string&)
+    {
+        return
+R"(#ifndef _BRDF_SPECULAR_NDF_GGX_TROWBRIDGE_REITZ_INCLUDED_
+#define _BRDF_SPECULAR_NDF_GGX_TROWBRIDGE_REITZ_INCLUDED_
+
+float GGXTrowbridgeReitz(in float a2, in float NdotH)
+{
+    float denom = NdotH*NdotH * (a2 - 1.0) + 1.0;
+    return a2 / (3.14159265359 * denom*denom);
+}
+
+#endif
+)";
+    }
+    static std::string getGGXSmith(const std::string&)
+    {
+        return
+R"(#ifndef _BRDF_SPECULAR_GEOM_GGX_SMITH_INCLUDED_
+#define _BRDF_SPECULAR_GEOM_GGX_SMITH_INCLUDED_
+
+float _GGXSmith_G1_(in float a2, in float NdotX)
+{
+    return (2.0*NdotX) / (NdotX + sqrt(a2 + (1.0 - a2)*NdotX*NdotX));
+}
+
+float GGXSmith(in float a2, in float NdotL, in float NdotV)
+{
+    return _GGXSmith_G1_(a2, NdotL) * _GGXSmith_G1_(a2, NdotV);
+}
+
+#endif
+)";
+    }
+    static std::string getFresnelSchlick(const std::string&)
+    {
+        return
+R"(#ifndef _BRDF_SPECULAR_FRESNEL_FRESNEL_SCHLICK_INCLUDED_
+#define _BRDF_SPECULAR_FRESNEL_FRESNEL_SCHLICK_INCLUDED_
+
+vec3 FresnelSchlick(in vec3 F0, in float NdotV)
+{
+    return F0 + (1.0 - F0) * pow(1.0 - NdotV, 5.0);
+} 
+
+#endif
+)";
+    }
+
 protected:
     irr::core::vector<std::pair<std::regex, HandleFunc_t>> getBuiltinNamesToFunctionMapping() const override
     {
-        /* TODO */
         return {
-            { std::regex{"diffuse/lambert\\.glsl"}, [this](const std::string&) { return nullptr; }},
-            { std::regex{"diffuse/oren_nayar\\.glsl"}, [](const std::string&) { return nullptr; }},
-            { std::regex{"specular/ndf/ggx_trowbridge_reitz\\.glsl"}, nullptr },
-            { std::regex{"specular/geom/ggx_smith\\.glsl"}, nullptr },
-            { std::regex{"specular/fresnel/fresnel_schlick\\.glsl"}, nullptr }
+            { std::regex{"diffuse/oren_nayar\\.glsl"}, &getOrenNayar },
+            { std::regex{"specular/ndf/ggx_trowbridge_reitz\\.glsl"}, &getGGXTrowbridgeReitz },
+            { std::regex{"specular/geom/ggx_smith\\.glsl"}, &getGGXSmith },
+            { std::regex{"specular/fresnel/fresnel_schlick\\.glsl"}, &getFresnelSchlick }
         };
     }
 };

examples_tests/13.BRDF_Explorer/main.cpp

@@ -2,6 +2,7 @@
 
 #include <irrlicht.h>
 #include "BRDFExplorerApp.h"
+#include "CBRDFBuiltinIncludeLoader.h"
 
 using namespace irr;
 
@@ -36,6 +37,12 @@ int main()
     camera->setFarValue(1000.0f);
     smgr->setActiveCamera(camera);
 
+    {
+    auto brdfBuiltinLoader = new CBRDFBuiltinIncludeLoader();
+    device->getIncludeHandler()->addBuiltinIncludeLoader(brdfBuiltinLoader);
+    brdfBuiltinLoader->drop();
+    }
+
     auto* brdfExplorerApp = new BRDFExplorerApp(device, camera);
 
     uint64_t lastFPSTime = 0;