diff --git a/examples/models/resources/shaders/brdf.fs b/examples/models/resources/shaders/brdf.fs
index 59ae384ae..3e8777d2b 100644
--- a/examples/models/resources/shaders/brdf.fs
+++ b/examples/models/resources/shaders/brdf.fs
@@ -1,12 +1,15 @@
/*******************************************************************************************
*
-* rPBR [shader] - Bidirectional reflectance distribution function fragment shader
+* BRDF LUT Generation - Bidirectional reflectance distribution function fragment shader
+*
+* REF: https://github.com/HectorMF/BRDFGenerator
*
* Copyright (c) 2017 Victor Fisac
*
**********************************************************************************************/
#version 330
+
#define MAX_SAMPLES 1024u
// Input vertex attributes (from vertex shader)
@@ -18,43 +21,30 @@ const float PI = 3.14159265359;
// Output fragment color
out vec4 finalColor;
-float DistributionGGX(vec3 N, vec3 H, float roughness);
-float RadicalInverse_VdC(uint bits);
vec2 Hammersley(uint i, uint N);
-vec3 ImportanceSampleGGX(vec2 Xi, vec3 N, float roughness);
+float RadicalInverseVdC(uint bits);
float GeometrySchlickGGX(float NdotV, float roughness);
float GeometrySmith(vec3 N, vec3 V, vec3 L, float roughness);
+vec3 ImportanceSampleGGX(vec2 Xi, vec3 N, float roughness);
vec2 IntegrateBRDF(float NdotV, float roughness);
-float DistributionGGX(vec3 N, vec3 H, float roughness)
-{
- float a = roughness*roughness;
- float a2 = a*a;
- float NdotH = max(dot(N, H), 0.0);
- float NdotH2 = NdotH*NdotH;
-
- float nom = a2;
- float denom = (NdotH2*(a2 - 1.0) + 1.0);
- denom = PI*denom*denom;
-
- return nom/denom;
-}
-
-float RadicalInverse_VdC(uint bits)
+float RadicalInverseVdC(uint bits)
{
- bits = (bits << 16u) | (bits >> 16u);
- bits = ((bits & 0x55555555u) << 1u) | ((bits & 0xAAAAAAAAu) >> 1u);
- bits = ((bits & 0x33333333u) << 2u) | ((bits & 0xCCCCCCCCu) >> 2u);
- bits = ((bits & 0x0F0F0F0Fu) << 4u) | ((bits & 0xF0F0F0F0u) >> 4u);
- bits = ((bits & 0x00FF00FFu) << 8u) | ((bits & 0xFF00FF00u) >> 8u);
- return float(bits) * 2.3283064365386963e-10; // / 0x100000000
+ bits = (bits << 16u) | (bits >> 16u);
+ bits = ((bits & 0x55555555u) << 1u) | ((bits & 0xAAAAAAAAu) >> 1u);
+ bits = ((bits & 0x33333333u) << 2u) | ((bits & 0xCCCCCCCCu) >> 2u);
+ bits = ((bits & 0x0F0F0F0Fu) << 4u) | ((bits & 0xF0F0F0F0u) >> 4u);
+ bits = ((bits & 0x00FF00FFu) << 8u) | ((bits & 0xFF00FF00u) >> 8u);
+ return float(bits) * 2.3283064365386963e-10; // / 0x100000000
}
+// Compute Hammersley coordinates
vec2 Hammersley(uint i, uint N)
{
- return vec2(float(i)/float(N), RadicalInverse_VdC(i));
+ return vec2(float(i)/float(N), RadicalInverseVdC(i));
}
+// Integrate number of importance samples for (roughness and NoV)
vec3 ImportanceSampleGGX(vec2 Xi, vec3 N, float roughness)
{
float a = roughness*roughness;
@@ -85,6 +75,7 @@ float GeometrySchlickGGX(float NdotV, float roughness)
return nom/denom;
}
+// Compute the geometry term for the BRDF given roughness squared, NoV, NoL
float GeometrySmith(vec3 N, vec3 V, vec3 L, float roughness)
{
float NdotV = max(dot(N, V), 0.0);
@@ -97,29 +88,31 @@ float GeometrySmith(vec3 N, vec3 V, vec3 L, float roughness)
vec2 IntegrateBRDF(float NdotV, float roughness)
{
- vec3 V = vec3(sqrt(1.0 - NdotV*NdotV), 0.0, NdotV);
float A = 0.0;
- float B = 0.0;
+ float B = 0.0;
+ vec3 V = vec3(sqrt(1.0 - NdotV*NdotV), 0.0, NdotV);
vec3 N = vec3(0.0, 0.0, 1.0);
- for(uint i = 0u; i < MAX_SAMPLES; i++)
+ for (int i = 0; i < MAX_SAMPLES; i++)
{
// Generate a sample vector that's biased towards the preferred alignment direction (importance sampling)
- vec2 Xi = Hammersley(i, MAX_SAMPLES);
- vec3 H = ImportanceSampleGGX(Xi, N, roughness);
- vec3 L = normalize(2.0*dot(V, H)*H - V);
- float NdotL = max(L.z, 0.0);
- float NdotH = max(H.z, 0.0);
- float VdotH = max(dot(V, H), 0.0);
+
+ vec2 Xi = Hammersley(i, MAX_SAMPLES); // Compute a Hammersely coordinate
+ vec3 H = ImportanceSampleGGX(Xi, N, roughness); // Integrate number of importance samples for (roughness and NoV)
+ vec3 L = normalize(2.0*dot(V, H)*H - V); // Compute reflection vector L
+
+ float NdotL = max(L.z, 0.0); // Compute normal dot light
+ float NdotH = max(H.z, 0.0); // Compute normal dot half
+ float VdotH = max(dot(V, H), 0.0); // Compute view dot half
if (NdotL > 0.0)
{
- float G = GeometrySmith(N, V, L, roughness);
- float G_Vis = (G*VdotH)/(NdotH*NdotV);
- float Fc = pow(1.0 - VdotH, 5.0);
+ float G = GeometrySmith(N, V, L, roughness); // Compute the geometry term for the BRDF given roughness squared, NoV, NoL
+ float GVis = (G*VdotH)/(NdotH*NdotV); // Compute the visibility term given G, VoH, NoH, NoV, NoL
+ float Fc = pow(1.0 - VdotH, 5.0); // Compute the fresnel term given VoH
- A += (1.0 - Fc)*G_Vis;
- B += Fc*G_Vis;
+ A += (1.0 - Fc)*GVis; // Sum the result given fresnel, geometry, visibility
+ B += Fc*GVis;
}
}
diff --git a/src/rlgl.h b/src/rlgl.h
index 2b5756140..8c7526fbc 100644
--- a/src/rlgl.h
+++ b/src/rlgl.h
@@ -3221,6 +3221,7 @@ Texture2D GenTexturePrefilter(Shader shader, Texture2D cubemap, int size)
// Generate BRDF texture using cubemap data
// NOTE: OpenGL ES 2.0 does not support GL_RGB16F texture format, neither GL_DEPTH_COMPONENT24
+// TODO: Review implementation: https://github.com/HectorMF/BRDFGenerator
Texture2D GenTextureBRDF(Shader shader, int size)
{
Texture2D brdf = { 0 };
@@ -3229,9 +3230,9 @@ Texture2D GenTextureBRDF(Shader shader, int size)
glGenTextures(1, &brdf.id);
glBindTexture(GL_TEXTURE_2D, brdf.id);
#if defined(GRAPHICS_API_OPENGL_33)
- glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB32F, size, size, 0, GL_RG, GL_FLOAT, NULL);
+ glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB32F, size, size, 0, GL_RGB, GL_FLOAT, NULL);
#elif defined(GRAPHICS_API_OPENGL_ES2)
- if (texFloatSupported) glTexImage2D(GL_TEXTURE_2D, 0, GL_RG, size, size, 0, GL_RG, GL_FLOAT, NULL);
+ if (texFloatSupported) glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, size, size, 0, GL_RGB, GL_FLOAT, NULL);
#endif
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
@@ -3269,6 +3270,8 @@ Texture2D GenTextureBRDF(Shader shader, int size)
brdf.width = size;
brdf.height = size;
+ brdf.mipmaps = 1;
+ brdf.format = UNCOMPRESSED_R32G32B32;
#endif
return brdf;
}