Specular BDRF

.gitattributes

@@ -2,3 +2,4 @@
 *.mtl filter=lfs diff=lfs merge=lfs -text
 *.jpg filter=lfs diff=lfs merge=lfs -text
 *.png filter=lfs diff=lfs merge=lfs -text
+*.hdr filter=lfs diff=lfs merge=lfs -text

Shaders/BRDFIntegration.fs

@@ -0,0 +1,111 @@
+#version 460 core
+out vec2 FragColor;
+in vec2 TexCoords;
+
+
+const float PI = 3.14159265359;
+
+
+// http://holger.dammertz.org/stuff/notes_HammersleyOnHemisphere.html
+// efficient VanDerCorpus calculation.
+float RadicalInverse_VdC(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
+}
+
+vec2 Hammersley(uint i, uint N)
+{
+	return vec2(float(i)/float(N), RadicalInverse_VdC(i));
+}
+
+float GeometrySchlickGGX(float NdotV, float roughness)
+{
+    float a = roughness;
+    float k = (a * a) / 2.0;
+
+    float nom   = NdotV;
+    float denom = NdotV * (1.0 - k) + k;
+
+    return nom / denom;
+}
+
+vec3 ImportanceSampleGGX(vec2 Xi, vec3 N, float roughness){
+    float a = roughness*roughness;
+
+    float phi = 2.0 * PI * Xi.x;
+    float cosTheta = sqrt((1.0 - Xi.y) / (1.0 + (a*a - 1.0) * Xi.y));
+    float sinTheta = sqrt(1.0 - cosTheta*cosTheta);
+
+    // Spherical to cartesian
+    vec3 H;
+    H.x = cos(phi) * sinTheta;
+    H.y = sin(phi) * sinTheta;
+    H.z = cosTheta;
+
+    // tangent space to world sample vector
+    vec3 up = abs(N.z) < 0.999 ? vec3(0.0, 0.0, 1.0) : vec3(1.0, 0.0, 0.0);
+    vec3 tangent = normalize(cross(up,N));
+    vec3 bitangent = cross(N, tangent);
+    vec3 sampleVec = tangent * H.x + bitangent * H.y + N * H.z;
+
+    return normalize(sampleVec);
+}
+
+
+float GeometrySmith(vec3 N, vec3 V, vec3 L, float roughness)
+{
+    float NdotV = max(dot(N, V), 0.0);
+    float NdotL = max(dot(N, L), 0.0);
+    float ggx2 = GeometrySchlickGGX(NdotV, roughness);
+    float ggx1 = GeometrySchlickGGX(NdotL, roughness);
+
+    return ggx1 * ggx2;
+}  
+
+vec2 IntegrateBRDF (float NdotV, float roughness){
+
+    vec3 V;
+    V.x = sqrt(1.0 - NdotV * NdotV);
+    V.y = 0.0;
+    V.z = NdotV;
+
+    float A = 0.0;
+    float B = 0.0;
+    
+    vec3 N = vec3(0.0,0.0,1.0);
+
+    const uint SAMPLE_COUNT = 1024u;
+    for(uint i = 0u; i < SAMPLE_COUNT; ++i){
+       vec2 Xi = Hammersley(i, SAMPLE_COUNT);
+        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);
+
+        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);
+
+            A += (1.0 - Fc) * G_Vis;
+            B += Fc * G_Vis;
+        }
+    }
+    A /= float(SAMPLE_COUNT);
+    B /= float(SAMPLE_COUNT);
+    return vec2(A, B);
+}
+
+void main() 
+{
+    vec2 integratedBRDF = IntegrateBRDF(TexCoords.x, TexCoords.y);
+    FragColor = integratedBRDF;
+}

Shaders/BRDFIntegration.vs

@@ -0,0 +1,10 @@
+#version 460 core
+layout (location = 0) in vec3 aPos;
+layout (location = 1) in vec2 aTexCoords;
+
+out vec2 TexCoords;
+
+void main(){
+    TexCoords = aTexCoords;
+    gl_Position = vec4(aPos, 1.0);
+}

Shaders/HDRMap.fs

@@ -0,0 +1,22 @@
+#version 460 core
+out vec4 FragColor;
+in vec3 localPos;
+
+uniform sampler2D equirectangularMap;
+
+const vec2 invAtan = vec2(0.1591, 0.3183);
+
+vec2 SampleSphericalMap(vec3 v)
+{
+    vec2 uv = vec2(atan(v.z, v.x), asin(v.y));
+    uv *= invAtan;
+    uv += 0.5;
+    return uv;
+}
+
+void main(){
+    vec2 uv = SampleSphericalMap(localPos);
+    vec3 color = texture(equirectangularMap, uv).rgb;
+
+    FragColor = vec4(color,1.0);
+}

Shaders/HDRMap.vs

@@ -0,0 +1,12 @@
+#version 460 core
+layout (location = 0) in vec3 aPos;
+
+out vec3 localPos;
+
+uniform mat4 projection;
+uniform mat4 view;
+
+void main(){
+    localPos = aPos;
+    gl_Position = projection * view * vec4(localPos, 1.0);
+}

Shaders/HDRSkybox.fs

@@ -0,0 +1,15 @@
+#version 460 core
+out vec4 FragColor;
+
+in vec3 localPos;
+
+uniform samplerCube environmentMap;
+
+void main(){
+    vec3 envColor = texture(environmentMap, localPos).rgb;
+    envColor = envColor /(envColor + vec3(1.0));
+    envColor = pow(envColor, vec3(1.0/2.2));
+
+    FragColor = vec4(envColor,1.0);
+
+}

Shaders/HDRSkybox.vs

@@ -0,0 +1,16 @@
+#version 460 core
+layout (location = 0) in vec3 aPos;
+
+uniform mat4 projection;
+uniform mat4 view;
+
+out vec3 localPos;
+
+void main(){
+    localPos = aPos;
+
+    mat4 rotView = mat4(mat3(view));
+    vec4 clipPos = projection * rotView * vec4(localPos,1.0);
+
+    gl_Position = clipPos.xyww;
+}

Shaders/irradienceconv.fs

@@ -0,0 +1,35 @@
+#version 460 core
+out vec4 FragColor;
+in vec3 localPos;
+
+uniform samplerCube environmentMap;
+
+const float PI = 3.14159265359;
+
+void main(){
+    vec3 normal = normalize(localPos);
+
+    vec3 irradiance = vec3(0.0);
+
+    vec3 up = vec3(0.0, 1.0, 0.0);
+    vec3 right = normalize(cross(up, normal));
+    up = normalize(cross(normal, right));
+
+    float sampleDelta = 0.025;
+    float nrSamples = 0.0;
+
+    for(float phi = 0.0; phi < 2.0 * PI; phi += sampleDelta){
+        for(float theta = 0.0; theta < 0.5 * PI; theta += sampleDelta){
+            // spherical to cartesian
+            vec3 tangentSample = vec3(sin(theta) * cos(phi), sin(theta) * sin(phi), cos(theta));
+            // tangent space to world
+            vec3 sampleVec = tangentSample.x * right + tangentSample.y * up + tangentSample.z * normal;
+
+
+            irradiance += texture(environmentMap, sampleVec).rgb * cos(theta) * sin(theta);
+            nrSamples++;
+        }
+    }
+    irradiance = PI * irradiance * (1.0 / float(nrSamples));
+    FragColor = vec4(irradiance,1.0);
+}

Shaders/pbr.fs

@@ -13,6 +13,11 @@ uniform sampler2D normalMap;
 uniform sampler2D roughnessMap;
 uniform sampler2D aoMap;
 
+
+uniform samplerCube irradianceMap;
+uniform samplerCube prefilterMap;
+uniform sampler2D brdfLUT;
+
 uniform vec3 lightPositions[4];
 uniform vec3 lightColors[4];
 
@@ -21,9 +26,9 @@ const float PI = 3.14159265359;
 
 
 // ratio Refraction vs Reflection (F function)
-vec3 fresnelSchlick (float cosTheta, vec3 F0)
+vec3 fresnelSchlick (float cosTheta, vec3 F0, float roughness)
 {
-    return F0 + (1.0 - F0) * pow(clamp(1.0 - cosTheta, 0.0, 1.0), 5.0);
+    return F0 + (max(vec3(1.0- roughness), F0)- F0) * pow(clamp(1.0 - cosTheta, 0.0, 1.0), 5.0);
 }
 
 // Calculate Normal distribution (D function)
@@ -76,6 +81,8 @@ vec3 getNormalFromNormalMap(){
     return normalize(TBN * tangentNormal);
 }
 
+
+
 void main(){
 
     vec3 albedo = pow(texture(albedoMap, TexCoords).rgb, vec3(2.2));
@@ -86,7 +93,9 @@ void main(){
 
     vec3 N = getNormalFromNormalMap();
     vec3 V = normalize(camPos - WorldPos);
-    
+    vec3 R = reflect(-V, N);
+
+
     vec3 F0 = vec3(0.04);
     F0 = mix(F0, albedo, metallic);
 
@@ -102,7 +111,7 @@ void main(){
         
         float NDF = DistributionGGX(N,H, roughness);
         float G = GeometrySmith(N,V,L, roughness);
-        vec3 F = fresnelSchlick(max(dot(H,V), 0.0), F0);
+        vec3 F = fresnelSchlick(max(dot(H,V), 0.0), F0, roughness);
 
         vec3 kS = F;
         vec3 kD = vec3(1.0) - kS;
@@ -118,8 +127,23 @@ void main(){
         Lo += (kD * albedo / PI + specular) * radiance * NdotL;
     }
 
+    
+
     // Calculate the ambient term and add it 
-    vec3 ambient = vec3(0.03) * albedo * ao;
+    vec3 kS = fresnelSchlick(max(dot(N,V), 0.0), F0, roughness);
+    vec3 kD = 1.0 - kS;
+    kD *= 1.0 - metallic;
+    vec3 irradiance = texture(irradianceMap, N).rgb;
+    vec3 diffuse = irradiance* albedo;
+
+    const float MAX_REFLECTION_LOD = 4.0;
+    vec3 prefilterColor = textureLod(prefilterMap, R, roughness * MAX_REFLECTION_LOD).rgb;
+    vec2 envBRDF = texture(brdfLUT, vec2(max(dot(N,V), 0.0), roughness)).rg;
+    vec3 specular = prefilterColor * (kS * envBRDF.x + envBRDF.y);
+
+
+
+    vec3 ambient = (kD * diffuse + specular) * ao;
     vec3 color = ambient + Lo;
 
     // HDR tonemapping

Shaders/prefilter.fs

@@ -0,0 +1,71 @@
+#version 460 core
+out vec4 FragColor;
+in vec3 localPos;
+
+uniform samplerCube environmentMap;
+uniform float roughness;
+
+const float PI = 3.14159265359;
+
+vec3 ImportanceSampleGGX(vec2 Xi, vec3 N, float roughness){
+    float a = roughness*roughness;
+
+    float phi = 2.0 * PI * Xi.x;
+    float cosTheta = sqrt((1.0 - Xi.y) / (1.0 + (a*a - 1.0) * Xi.y));
+    float sinTheta = sqrt(1.0 - cosTheta*cosTheta);
+
+    // Spherical to cartesian
+    vec3 H;
+    H.x = cos(phi) * sinTheta;
+    H.y = sin(phi) * sinTheta;
+    H.z = cosTheta;
+
+    // tangent space to world sample vector
+    vec3 up = abs(N.z) < 0.999 ? vec3(0.0, 0.0, 1.0) : vec3(1.0, 0.0, 0.0);
+    vec3 tangent = normalize(cross(up,N));
+    vec3 bitangent = cross(N, tangent);
+    vec3 sampleVec = tangent * H.x + bitangent * H.y + N * H.z;
+
+    return normalize(sampleVec);
+}
+
+
+// Generate Van Der Corput sequence
+float RadicalInverse_VdC(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
+}
+
+vec2 Hammersley(uint i, uint N){
+    return vec2(float(i)/float(N), RadicalInverse_VdC(i));
+}
+
+void main(){
+    vec3 N = normalize(localPos);
+    vec3 R = N;
+    vec3 V = R;
+    
+    const uint SAMPLE_COUNT = 1024u;
+    float totalWeight = 0.0;
+    vec3 prefilteredColor = vec3(0.0);
+    for(uint i = 0u; i < SAMPLE_COUNT; ++i)
+    {
+        vec2 Xi = Hammersley(i, SAMPLE_COUNT);
+        vec3 H = ImportanceSampleGGX(Xi, N, roughness);
+        vec3 L = normalize(2.0 * dot(V,H) * H - V );
+
+        float NdotL = max(dot(N, L), 0.0);
+        if(NdotL > 0.0){
+            prefilteredColor += texture(environmentMap, L).rgb * NdotL;
+            totalWeight += NdotL;
+        }
+    }
+
+    prefilteredColor = prefilteredColor / totalWeight;
+
+    FragColor = vec4(prefilteredColor, 1.0);
+}

Shaders/skybox2.vs

@@ -0,0 +1,13 @@
+#version 460 core
+layout (location = 0) in vec3 aPos;
+
+out vec3 localPos;
+
+uniform mat4 projection;
+uniform mat4 view;
+
+void main()
+{
+    localPos = aPos;
+    gl_Position = projection * view * vec4(localPos ,1.0);
+}

src/Primitives/Skybox.cpp

@@ -17,6 +17,7 @@ void Skybox::Destroy() {
     std::cout << "Skybox destroyed!" << std::endl;
 }
 
+
 void Skybox::loadCubeTextures(const std::vector<std::string>& texture_faces)
 {
     glGenTextures(1, &id);

src/Primitives/texture.h

@@ -9,4 +9,5 @@ struct Texture{
    std::string path;
 };
 
+
 Texture* CreateTexture(unsigned int width, unsigned int height);

src/Renderer/Renderer.cpp

@@ -11,9 +11,11 @@
 #include <glm/gtc/type_ptr.hpp>
 #include "../Primitives/Scene.h"
 #include "../model.h"
+#include "../Utils.h"
 static enum class RenderPass {
     NONE = 0,
     SKYBOX,
+    HDR_SKYBOX,
     DEFAULT,
     PBR
 };
@@ -43,8 +45,119 @@ unsigned int normal;
 unsigned int metallic;
 unsigned int roughness;
 unsigned int ao;
+
+
+unsigned int cubeVAO = 0; 
+unsigned int cubeVBO = 0;
+void renderCube() {
+    if (cubeVAO == 0) {
+        float vertices[] = {
+            // back face
+            -1.0f, -1.0f, -1.0f,  0.0f,  0.0f, -1.0f, 0.0f, 0.0f, // bottom-left
+             1.0f,  1.0f, -1.0f,  0.0f,  0.0f, -1.0f, 1.0f, 1.0f, // top-right
+             1.0f, -1.0f, -1.0f,  0.0f,  0.0f, -1.0f, 1.0f, 0.0f, // bottom-right         
+             1.0f,  1.0f, -1.0f,  0.0f,  0.0f, -1.0f, 1.0f, 1.0f, // top-right
+            -1.0f, -1.0f, -1.0f,  0.0f,  0.0f, -1.0f, 0.0f, 0.0f, // bottom-left
+            -1.0f,  1.0f, -1.0f,  0.0f,  0.0f, -1.0f, 0.0f, 1.0f, // top-left
+            // front face
+            -1.0f, -1.0f,  1.0f,  0.0f,  0.0f,  1.0f, 0.0f, 0.0f, // bottom-left
+             1.0f, -1.0f,  1.0f,  0.0f,  0.0f,  1.0f, 1.0f, 0.0f, // bottom-right
+             1.0f,  1.0f,  1.0f,  0.0f,  0.0f,  1.0f, 1.0f, 1.0f, // top-right
+             1.0f,  1.0f,  1.0f,  0.0f,  0.0f,  1.0f, 1.0f, 1.0f, // top-right
+            -1.0f,  1.0f,  1.0f,  0.0f,  0.0f,  1.0f, 0.0f, 1.0f, // top-left
+            -1.0f, -1.0f,  1.0f,  0.0f,  0.0f,  1.0f, 0.0f, 0.0f, // bottom-left
+            // left face
+            -1.0f,  1.0f,  1.0f, -1.0f,  0.0f,  0.0f, 1.0f, 0.0f, // top-right
+            -1.0f,  1.0f, -1.0f, -1.0f,  0.0f,  0.0f, 1.0f, 1.0f, // top-left
+            -1.0f, -1.0f, -1.0f, -1.0f,  0.0f,  0.0f, 0.0f, 1.0f, // bottom-left
+            -1.0f, -1.0f, -1.0f, -1.0f,  0.0f,  0.0f, 0.0f, 1.0f, // bottom-left
+            -1.0f, -1.0f,  1.0f, -1.0f,  0.0f,  0.0f, 0.0f, 0.0f, // bottom-right
+            -1.0f,  1.0f,  1.0f, -1.0f,  0.0f,  0.0f, 1.0f, 0.0f, // top-right
+            // right face
+             1.0f,  1.0f,  1.0f,  1.0f,  0.0f,  0.0f, 1.0f, 0.0f, // top-left
+             1.0f, -1.0f, -1.0f,  1.0f,  0.0f,  0.0f, 0.0f, 1.0f, // bottom-right
+             1.0f,  1.0f, -1.0f,  1.0f,  0.0f,  0.0f, 1.0f, 1.0f, // top-right         
+             1.0f, -1.0f, -1.0f,  1.0f,  0.0f,  0.0f, 0.0f, 1.0f, // bottom-right
+             1.0f,  1.0f,  1.0f,  1.0f,  0.0f,  0.0f, 1.0f, 0.0f, // top-left
+             1.0f, -1.0f,  1.0f,  1.0f,  0.0f,  0.0f, 0.0f, 0.0f, // bottom-left     
+             // bottom face
+             -1.0f, -1.0f, -1.0f,  0.0f, -1.0f,  0.0f, 0.0f, 1.0f, // top-right
+              1.0f, -1.0f, -1.0f,  0.0f, -1.0f,  0.0f, 1.0f, 1.0f, // top-left
+              1.0f, -1.0f,  1.0f,  0.0f, -1.0f,  0.0f, 1.0f, 0.0f, // bottom-left
+              1.0f, -1.0f,  1.0f,  0.0f, -1.0f,  0.0f, 1.0f, 0.0f, // bottom-left
+             -1.0f, -1.0f,  1.0f,  0.0f, -1.0f,  0.0f, 0.0f, 0.0f, // bottom-right
+             -1.0f, -1.0f, -1.0f,  0.0f, -1.0f,  0.0f, 0.0f, 1.0f, // top-right
+             // top face
+             -1.0f,  1.0f, -1.0f,  0.0f,  1.0f,  0.0f, 0.0f, 1.0f, // top-left
+              1.0f,  1.0f , 1.0f,  0.0f,  1.0f,  0.0f, 1.0f, 0.0f, // bottom-right
+              1.0f,  1.0f, -1.0f,  0.0f,  1.0f,  0.0f, 1.0f, 1.0f, // top-right     
+              1.0f,  1.0f,  1.0f,  0.0f,  1.0f,  0.0f, 1.0f, 0.0f, // bottom-right
+             -1.0f,  1.0f, -1.0f,  0.0f,  1.0f,  0.0f, 0.0f, 1.0f, // top-left
+             -1.0f,  1.0f,  1.0f,  0.0f,  1.0f,  0.0f, 0.0f, 0.0f  // bottom-left        
+        };
+        glGenVertexArrays(1, &cubeVAO);
+        glGenBuffers(1, &cubeVBO);
+        // fill buffer
+        glBindBuffer(GL_ARRAY_BUFFER, cubeVBO);
+        glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
+        // link vertex attributes
+        glBindVertexArray(cubeVAO);
+        glEnableVertexAttribArray(0);
+        glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0);
+        glEnableVertexAttribArray(1);
+        glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(3 * sizeof(float)));
+        glEnableVertexAttribArray(2);
+        glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(6 * sizeof(float)));
+        glBindBuffer(GL_ARRAY_BUFFER, 0);
+        glBindVertexArray(0);
+
+    }
+
+    // render Cube
+    glBindVertexArray(cubeVAO);
+    glDrawArrays(GL_TRIANGLES, 0, 36);
+    glBindVertexArray(0);
+}
+
+unsigned int quadVAO = 0;
+unsigned int quadVBO;
+void renderQuad()
+{
+    if (quadVAO == 0)
+    {
+        float quadVertices[] = {
+            // positions        // texture Coords
+            -1.0f,  1.0f, 0.0f, 0.0f, 1.0f,
+            -1.0f, -1.0f, 0.0f, 0.0f, 0.0f,
+             1.0f,  1.0f, 0.0f, 1.0f, 1.0f,
+             1.0f, -1.0f, 0.0f, 1.0f, 0.0f,
+        };
+        // setup plane VAO
+        glGenVertexArrays(1, &quadVAO);
+        glGenBuffers(1, &quadVBO);
+        glBindVertexArray(quadVAO);
+        glBindBuffer(GL_ARRAY_BUFFER, quadVBO);
+        glBufferData(GL_ARRAY_BUFFER, sizeof(quadVertices), &quadVertices, GL_STATIC_DRAW);
+        glEnableVertexAttribArray(0);
+        glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)0);
+        glEnableVertexAttribArray(1);
+        glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(3 * sizeof(float)));
+    }
+    glBindVertexArray(quadVAO);
+    glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
+    glBindVertexArray(0);
+}
+
+
+
+unsigned int brdfLUTTexture;
+unsigned int prefilterMap;
+unsigned int irradianceMap;
+unsigned int envCubemap;
+unsigned int envMapVAO;
 void Renderer::Setup()
 {
+    glEnable(GL_TEXTURE_CUBE_MAP_SEAMLESS);
     // Create ScreenVAO
     glGenVertexArrays(1, &ScreenVAO);
     glBindVertexArray(ScreenVAO);
@@ -70,17 +183,239 @@ void Renderer::Setup()
     // Load shaders 
     shaders[static_cast<int>(RenderPass::SKYBOX)] = Shader();
     shaders[static_cast<int>(RenderPass::SKYBOX)].Load("../Shaders/skybox.vs", "../Shaders/Cubemap.fs");
+    shaders[static_cast<int>(RenderPass::HDR_SKYBOX)] = Shader();
+    shaders[static_cast<int>(RenderPass::HDR_SKYBOX)].Load("../Shaders/HDRSkybox.vs", "../Shaders/HDRSkybox.fs");
     shaders[static_cast<int>(RenderPass::DEFAULT)] = Shader();
     shaders[static_cast<int>(RenderPass::DEFAULT)].Load("../Shaders/shader.vs", "../Shaders/shader.fs");
     shaders[static_cast<int>(RenderPass::PBR)] = Shader();
     shaders[static_cast<int>(RenderPass::PBR)].Load("../Shaders/pbr.vs", "../Shaders/pbr.fs");
 
 
-    albedo = TextureFromFile("../Textures/rusted_iron/albedo.png", ".");
+    albedo = TextureFromFile("../Textures/space-cruiser/albedo.png", ".");
-    normal = TextureFromFile("../Textures/rusted_iron/normal.png", ".");
+    normal = TextureFromFile("../Textures/space-cruiser/normal.png", ".");
-    metallic = TextureFromFile("../Textures/rusted_iron/metallic.png", ".");
+    metallic = TextureFromFile("../Textures/space-cruiser/metallic.png", ".");
-    roughness = TextureFromFile("../Textures/rusted_iron/roughness.png", ".");
+    roughness = TextureFromFile("../Textures/space-cruiser/roughness.png", ".");
-    ao = TextureFromFile("../Textures/rusted_iron/ao.png",".");
+    ao = TextureFromFile("../Textures/space-cruiser/ao.png",".");
+
+
+    // Create the skybox from an HDR equirectangular environment map 
+    unsigned int captureFBO, captureRBO;
+    glGenFramebuffers(1, &captureFBO);
+    glGenRenderbuffers(1, &captureRBO);
+
+    glBindFramebuffer(GL_FRAMEBUFFER, captureFBO);
+    glBindRenderbuffer(GL_RENDERBUFFER, captureRBO);
+    glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT24, 512, 512);
+    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, captureRBO);
+
+    glGenTextures(1, &envCubemap);
+    glBindTexture(GL_TEXTURE_CUBE_MAP, envCubemap);
+    for (unsigned int i = 0; i < 6; ++i) {
+        glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, GL_RGB16F, 512, 512, 0, GL_RGB, GL_FLOAT, nullptr);
+    }
+    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
+    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+
+    glm::mat4 captureProjection = glm::perspective(glm::radians(90.0f), 1.0f, 0.1f, 10.0f);
+    glm::mat4 captureViews[] = {
+        glm::lookAt(glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3(1.0f,  0.0f,  0.0f), glm::vec3(0.0f, -1.0f,  0.0f)),
+        glm::lookAt(glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3(-1.0f,  0.0f,  0.0f), glm::vec3(0.0f, -1.0f,  0.0f)),
+        glm::lookAt(glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3(0.0f,  1.0f,  0.0f), glm::vec3(0.0f,  0.0f,  1.0f)),
+        glm::lookAt(glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3(0.0f, -1.0f,  0.0f), glm::vec3(0.0f,  0.0f, -1.0f)),
+        glm::lookAt(glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3(0.0f,  0.0f,  1.0f), glm::vec3(0.0f, -1.0f,  0.0f)),
+        glm::lookAt(glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3(0.0f,  0.0f, -1.0f), glm::vec3(0.0f, -1.0f,  0.0f))
+    };
+
+    auto eqShader = Shader();
+    eqShader.Load("../Shaders/HDRMap.vs", "../Shaders/HDRMap.fs");
+
+    auto hdrTexture = LoadIBL("../Textures/night_2k.hdr");
+
+    eqShader.use();
+    eqShader.setInt("equirectangularMap", 0);
+    eqShader.setMat4("projection", captureProjection);
+    glActiveTexture(GL_TEXTURE0);
+    glBindTexture(GL_TEXTURE_2D, hdrTexture);
+    
+    glViewport(0, 0, 512, 512);
+
+    glBindFramebuffer(GL_FRAMEBUFFER, captureFBO);
+
+    for (unsigned int i = 0; i < 6; ++i) {
+        eqShader.setMat4("view", captureViews[i]);
+        glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, envCubemap, 0);
+        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+        renderCube();
+    }
+    glBindFramebuffer(GL_FRAMEBUFFER, 0);
+
+    // Generate irradiancemap
+    glGenTextures(1, &irradianceMap);
+    glBindTexture(GL_TEXTURE_CUBE_MAP, irradianceMap);
+    for (unsigned int i = 0; i < 6; ++i) {
+        glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, GL_RGB16F, 32, 32, 0, GL_RGB, GL_FLOAT, nullptr);
+    }
+    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
+    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+
+    glBindFramebuffer(GL_FRAMEBUFFER, captureFBO);
+    glBindRenderbuffer(GL_RENDERBUFFER, captureRBO);
+    glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT24, 32, 32);
+
+
+    auto irradianceShader = Shader();
+    irradianceShader.Load("../Shaders/skybox2.vs", "../Shaders/irradienceconv.fs");
+    irradianceShader.use();
+    irradianceShader.setInt("environmentMap", 0);
+    irradianceShader.setMat4("projection", captureProjection);
+    glActiveTexture(GL_TEXTURE0);
+    glBindTexture(GL_TEXTURE_CUBE_MAP, envCubemap);
+
+    glViewport(0, 0, 32, 32);
+    glBindFramebuffer(GL_FRAMEBUFFER, captureFBO);
+    for (unsigned int i = 0; i < 6; ++i) {
+        irradianceShader.setMat4("view", captureViews[i]);
+        glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, irradianceMap, 0);
+        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+        renderCube();
+    }
+    glViewport(0, 0, 800, 600); // restore viewport;
+    glBindFramebuffer(GL_FRAMEBUFFER, 0);
+
+
+
+
+    std::vector<float> m_skyboxVertices = {
+        // positions          
+        -1.0f,  1.0f, -1.0f,
+        -1.0f, -1.0f, -1.0f,
+        1.0f, -1.0f, -1.0f,
+        1.0f, -1.0f, -1.0f,
+        1.0f,  1.0f, -1.0f,
+        -1.0f,  1.0f, -1.0f,
+
+        -1.0f, -1.0f,  1.0f,
+        -1.0f, -1.0f, -1.0f,
+        -1.0f,  1.0f, -1.0f,
+        -1.0f,  1.0f, -1.0f,
+        -1.0f,  1.0f,  1.0f,
+        -1.0f, -1.0f,  1.0f,
+
+        1.0f, -1.0f, -1.0f,
+        1.0f, -1.0f,  1.0f,
+        1.0f,  1.0f,  1.0f,
+        1.0f,  1.0f,  1.0f,
+        1.0f,  1.0f, -1.0f,
+        1.0f, -1.0f, -1.0f,
+
+        -1.0f, -1.0f,  1.0f,
+        -1.0f,  1.0f,  1.0f,
+        1.0f,  1.0f,  1.0f,
+        1.0f,  1.0f,  1.0f,
+        1.0f, -1.0f,  1.0f,
+        -1.0f, -1.0f,  1.0f,
+
+        -1.0f,  1.0f, -1.0f,
+        1.0f,  1.0f, -1.0f,
+        1.0f,  1.0f,  1.0f,
+        1.0f,  1.0f,  1.0f,
+        -1.0f,  1.0f,  1.0f,
+        -1.0f,  1.0f, -1.0f,
+
+        -1.0f, -1.0f, -1.0f,
+        -1.0f, -1.0f,  1.0f,
+        1.0f, -1.0f, -1.0f,
+        1.0f, -1.0f, -1.0f,
+        -1.0f, -1.0f,  1.0f,
+        1.0f, -1.0f,  1.0f
+    };
+    unsigned int envMapVBO;
+
+    glGenVertexArrays(1, &envMapVAO);
+    glBindVertexArray(envMapVAO);
+
+    glGenBuffers(1, &envMapVBO);
+    glBindBuffer(GL_ARRAY_BUFFER, envMapVBO);
+
+    glBufferData(GL_ARRAY_BUFFER, m_skyboxVertices.size() * sizeof(float), &m_skyboxVertices[0], GL_STATIC_DRAW);
+
+    glEnableVertexAttribArray(0);
+    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
+
+    glBindVertexArray(0);
+
+    glGenTextures(1, &prefilterMap);
+    glBindTexture(GL_TEXTURE_CUBE_MAP, prefilterMap);
+    for (unsigned int i = 0; i < 6; ++i) {
+        glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, GL_RGB16F, 128, 128, 0, GL_RGB, GL_FLOAT, nullptr);
+    }
+    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
+    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
+    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+
+    glGenerateMipmap(GL_TEXTURE_CUBE_MAP);
+
+    auto prefilterShader = Shader();
+    prefilterShader.Load("../Shaders/skybox2.vs", "../Shaders/prefilter.fs");
+    prefilterShader.setInt("environmentMap", 0);
+    prefilterShader.setMat4("projection", captureProjection);
+    glActiveTexture(GL_TEXTURE0);
+    glBindTexture(GL_TEXTURE_CUBE_MAP, envCubemap);
+
+    glBindFramebuffer(GL_FRAMEBUFFER, captureFBO);
+    unsigned int maxMipLevels = 5;
+    for (unsigned int mip = 0; mip < maxMipLevels; ++mip) {
+        unsigned int mipWidth = 128 * std::pow(0.5, mip);
+        unsigned int mipHeight = 128 * std::pow(0.5, mip);
+        glBindRenderbuffer(GL_RENDERBUFFER, captureRBO);
+        glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT24, mipWidth, mipHeight);
+        glViewport(0, 0, mipWidth, mipHeight);
+
+        float roughness = (float)mip / (float)(maxMipLevels - 1);
+        prefilterShader.setFloat("roughness", roughness);
+        for (unsigned int i = 0; i < 6; ++i) {
+            prefilterShader.setMat4("view", captureViews[i]);
+            glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, prefilterMap, mip);
+            glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+            renderCube();
+        }
+    }
+
+    glGenTextures(1, &brdfLUTTexture);
+    
+    // Pre-allocate enough memory for the LUT texture
+    glBindTexture(GL_TEXTURE_2D, brdfLUTTexture);
+    glTexImage2D(GL_TEXTURE_2D, 0, GL_RG16F, 512, 512, 0, GL_RG, GL_FLOAT, 0);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+
+    glBindFramebuffer(GL_FRAMEBUFFER, captureFBO);
+    glBindRenderbuffer(GL_RENDERBUFFER, captureRBO);
+    glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT24, 512, 512);
+    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, brdfLUTTexture, 0);
+
+    glViewport(0, 0, 512, 512);
+    auto brdfShader = Shader();
+    brdfShader.Load("../Shaders/BRDFIntegration.vs", "../Shaders/BRDFIntegration.fs");
+
+    brdfShader.use();
+    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+    renderQuad();
+
+    glViewport(0, 0, 800, 600); // reset viewport
+    glBindFramebuffer(GL_FRAMEBUFFER, 0);
 
 
 }
@@ -127,8 +462,6 @@ void Renderer::resize(int width, int height ) {
 
 }
 
-
-
 unsigned int sphereVAO = 0;
 unsigned int indexCount;
 void renderSphere() {
@@ -221,9 +554,6 @@ void renderSphere() {
     glDrawElements(GL_TRIANGLE_STRIP, indexCount, GL_UNSIGNED_INT, 0);
 }
 
-
-
-
 void Renderer::Render(Scene& scene)
 {
    
@@ -235,6 +565,7 @@ void Renderer::Render(Scene& scene)
     auto model = glm::mat4(1.0f);   
 
     // Skybox 
+#if false
     glDepthMask(GL_FALSE);
     Shader shader = shaders.at(static_cast<int>(RenderPass::SKYBOX));
 
@@ -252,6 +583,28 @@ void Renderer::Render(Scene& scene)
     scene.skybox.Unbind();
 
     glDepthMask(GL_TRUE);
+#endif 
+
+    //HDR Environment Skybox 
+    Shader shader = shaders.at(static_cast<int>(RenderPass::HDR_SKYBOX));
+
+    glDepthFunc(GL_LEQUAL);
+
+    shader.use();
+
+    shader.setMat4("projection", projection);
+    shader.setMat4("view", scene.MainCamera.GetViewMatrix());
+
+    glBindVertexArray(envMapVAO);
+    glActiveTexture(GL_TEXTURE0);
+    glBindTexture(GL_TEXTURE_CUBE_MAP, envCubemap);
+
+    glDrawArrays(GL_TRIANGLES, 0, 36);
+
+    glBindTexture(GL_TEXTURE_CUBE_MAP, 0);
+    glBindVertexArray(0);
+
+    glDepthFunc(GL_LESS);
 
 
     // Phong lighting
@@ -284,6 +637,10 @@ void Renderer::Render(Scene& scene)
     shader.setInt("metallicMap", 2);
     shader.setInt("roughnessMap", 3);
     shader.setInt("aoMap", 4);
+    shader.setInt("irradianceMap", 5);
+    shader.setInt("prefilterMap", 6);
+    shader.setInt("brdfLUT", 7);
+
 
     shader.setMat4("projection", projection);
     view = scene.MainCamera.GetViewMatrix();
@@ -302,11 +659,20 @@ void Renderer::Render(Scene& scene)
     glActiveTexture(GL_TEXTURE3);
     glBindTexture(GL_TEXTURE_2D, roughness);
 
-
     glActiveTexture(GL_TEXTURE4);
     glBindTexture(GL_TEXTURE_2D, ao);
 
+    glActiveTexture(GL_TEXTURE5);
+    glBindTexture(GL_TEXTURE_CUBE_MAP, irradianceMap);
 
+    glActiveTexture(GL_TEXTURE6);
+    glBindTexture(GL_TEXTURE_CUBE_MAP, prefilterMap);
+
+    glActiveTexture(GL_TEXTURE7);
+    glBindTexture(GL_TEXTURE_2D, brdfLUTTexture);
+
+
+    // Render Spheres
     model = glm::mat4(1.0f);
     for (int row = 0; row < nrRows; ++row) {
         for (int col = 0; col < nrColumns; ++col) {
@@ -367,16 +733,10 @@ void Renderer::Render(Scene& scene)
         entity.Draw(OutlineShader);
     }
 
-            glStencilFunc(GL_ALWAYS, 1, 0xFF);
+    glStencilFunc(GL_ALWAYS, 1, 0xFF);
-            glStencilMask(0xFF);
+    glStencilMask(0xFF);
                 
-        */
+    */
-
-     
-    
-   
-
-   
 
     
     // 4. draw result to screen

src/Utils.h

@@ -0,0 +1,32 @@
+#pragma once
+#include <string>
+#include <iostream>
+#include <stb_image.h>
+#include <glad/glad.h>
+
+
+int LoadIBL(std::string file_path) {
+    stbi_set_flip_vertically_on_load(true);
+    int width, height, nrComponents;
+    float* data = stbi_loadf(file_path.c_str(), &width, &height, &nrComponents, 0);
+    unsigned int hdrTexture;
+
+    if (data) {
+        glGenTextures(1, &hdrTexture);
+        glBindTexture(GL_TEXTURE_2D, hdrTexture);
+        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB16F, width, height, 0, GL_RGB, GL_FLOAT, data);
+
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+
+        stbi_image_free(data);
+
+    }
+    else {
+        std::cout << "Failed to load HDR image." << std::endl;
+    }
+
+    return hdrTexture;
+}

src/main.cpp

@@ -71,8 +71,6 @@ public:
       renderer.Setup();
 
 
-
-
       //glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
       while(!window.shouldClose())
       {