FIrst step in Physically based rendering

Shaders/pbr.fs

@@ -0,0 +1,106 @@
+#version 460 core
+
+out vec4 FragColor;
+in vec2 TexCoords;
+in vec3 WorldPos;
+in vec3 Normal;
+
+uniform vec3 camPos;
+
+uniform vec3 albedo;
+uniform float metallic;
+uniform float roughness;
+uniform float ao;
+
+uniform vec3 lightPositions[4];
+uniform vec3 lightColors[4];
+
+const float PI = 3.14159265359;
+
+
+
+// ratio Refraction vs Reflection (F function)
+vec3 fresnelSchlick (float cosTheta, vec3 F0)
+{
+    return F0 + (1.0 - F0) * pow(clamp(1.0 - cosTheta, 0.0, 1.0), 5.0);
+}
+
+// Calculate Normal distribution (D function)
+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 num = a2;
+    float denom = (NdotH2 * ( a2 - 1.0) + 1.0);
+    denom = PI * denom * denom;
+    return num / denom;
+}
+
+// G function
+float GeometrySchlickGGX(float NdotV, float roughness){
+    float r = (roughness + 1.0);
+    float k = (r*r) / 8.0;
+    
+    float num = NdotV;
+    float denom = NdotV * (1.0 - k) + k;
+    
+    return num / denom;
+}
+
+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;
+}
+
+void main(){
+    vec3 N = normalize(Normal);
+    vec3 V = normalize(camPos - WorldPos);
+    
+    vec3 F0 = vec3(0.04);
+    F0 = mix(F0, albedo, metallic);
+
+    // Calculate the light contributions of each light source
+    vec3 Lo = vec3(0.0);
+    for( int i = 0; i < 4; ++i)
+    {
+        vec3 L = normalize(lightPositions[i] - WorldPos);
+        vec3 H = normalize(V + L);
+        float distance = length(lightPositions[i] - WorldPos);
+        float attenuation = 1.0/ (distance*distance);
+        vec3 radiance = lightColors[i] * attenuation;
+        
+        float NDF = DistributionGGX(N,H, roughness);
+        float G = GeometrySmith(N,V,L, roughness);
+        vec3 F = fresnelSchlick(max(dot(H,V), 0.0), F0);
+
+        vec3 kS = F;
+        vec3 kD = vec3(1.0) - kS;
+        kD *= 1.0 - metallic;
+
+
+        vec3 numerator = NDF * G * F;
+        float denominator = 4.0 * max(dot(N,V), 0.0) * max(dot(N, L), 0.0) + 0.0001;
+        vec3 specular = numerator /denominator;
+
+
+        float NdotL = max(dot(N,L), 0.0);
+        Lo += (kD * albedo / PI + specular) * radiance * NdotL;
+    }
+
+    // Calculate the ambient term and add it 
+    vec3 ambient = vec3(0.03) * albedo * ao;
+    vec3 color = ambient + Lo;
+
+    // Gamma correct the result 
+    color = color / (color + vec3(1.0));
+    color = pow(color, vec3(1.0/2.2));
+
+    FragColor = vec4(color, 1.0);
+}

Shaders/pbr.vs

@@ -0,0 +1,22 @@
+#version 460 core
+layout (location = 0) in vec3 aPos;
+layout (location = 1) in vec3 aNormal;
+layout (location = 2) in vec2 aTexCoords;
+
+out vec2 TexCoords;
+out vec3 WorldPos;
+out vec3 Normal;
+
+uniform mat4 projection;
+uniform mat4 view;
+uniform mat4 model;
+uniform mat3 normalMatrix;
+
+void main()
+{
+    TexCoords = aTexCoords;
+    WorldPos = vec3(model * vec4(aPos, 1.0));
+    Normal = normalMatrix * aNormal;   
+
+    gl_Position =  projection * view * vec4(WorldPos, 1.0);
+}

src/Primitives/shader.cpp

@@ -111,6 +111,11 @@ void Shader::setMat4(const std::string &name, glm::mat4 value)const{
     glUniformMatrix4fv(glGetUniformLocation(ID, name.c_str()), 1, GL_FALSE, &value[0][0] );
 }
 
+void Shader::setMat3(const std::string& name, glm::mat3 value) const
+{
+    glUniformMatrix3fv(glGetUniformLocation(ID, name.c_str()), 1, GL_FALSE, &value[0][0]);
+}
+
 void Shader::setVec3(const std::string &name, glm::vec3 value)const{
     glUniform3fv(glGetUniformLocation(ID, name.c_str()), 1, &value.x);
 }

src/Primitives/shader.h

@@ -22,6 +22,7 @@ class Shader
         void setInt(const std::string &name, int value)const;
         void setFloat(const std::string &name, float value)const;
         void setMat4(const std::string &name, glm::mat4 value)const;
+        void setMat3(const std::string& name, glm::mat3 value)const;
         void setVec3(const std::string &name, glm::vec3 value) const ;
 
 };

src/Renderer/Renderer.cpp

@@ -14,11 +14,29 @@ static enum class RenderPass {
     NONE = 0,
     SKYBOX,
     DEFAULT,
+    PBR
 };
 const int num_passes = static_cast<int>(RenderPass::DEFAULT) ;
 
 Texture* colourAttachment;
+glm::vec3 lightPositions[] = {
+    glm::vec3(-10.0f, 10.0f, 10.0f),
+    glm::vec3(10.0f, 10.0f, 10.0f),
 
+    glm::vec3(-10.0f, -10.0f, 10.0f),
+    glm::vec3(10.0f, -10.0f, 10.0f)
+};
+
+glm::vec3 lightColors[] = {
+    glm::vec3(300.0f, 300.0f, 300.0f),
+    glm::vec3(300.0f, 300.0f, 300.0f),
+    glm::vec3(300.0f, 300.0f, 300.0f),
+    glm::vec3(300.0f, 300.0f, 300.0f)
+};
+
+int nrRows = 7;
+int nrColumns = 7;
+float spacing = 2.5;
 
 void Renderer::Setup()
 {
@@ -49,6 +67,8 @@ void Renderer::Setup()
     shaders[static_cast<int>(RenderPass::SKYBOX)].Load("../Shaders/skybox.vs", "../Shaders/Cubemap.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");
 
 }
 
@@ -94,10 +114,107 @@ void Renderer::resize(int width, int height ) {
 
 }
 
+
+
+
+unsigned int sphereVAO = 0;
+unsigned int indexCount;
+void renderSphere() {
+    if (sphereVAO == 0) {
+        glGenVertexArrays(1, &sphereVAO);
+
+        unsigned int vbo, ebo;
+        glGenBuffers(1, &vbo);
+        glGenBuffers(1, &ebo);
+
+        std::vector<glm::vec3> positions;
+        std::vector<glm::vec2> uv;
+        std::vector<glm::vec3> normals;
+        std::vector<unsigned int> indices;
+
+        const unsigned int X_SEGMENTS = 64;
+        const unsigned int Y_SEGMENTS = 64;
+        const float PI = 3.14159265359f;
+        for (unsigned int x = 0; x <= X_SEGMENTS; ++x) {
+            for (unsigned int y = 0; y <= Y_SEGMENTS; ++y) {
+                float xSegment = (float)x / (float)X_SEGMENTS;
+                float ySegment = (float)y / (float)Y_SEGMENTS;
+                float xPos = std::cos(xSegment * 2.0f * PI) * std::sin(ySegment * PI);
+                float yPos = std::cos(ySegment * PI);
+                float zPos = std::sin(xSegment * 2.0f * PI) * std::sin(ySegment * PI);
+
+                positions.push_back(glm::vec3(xPos, yPos, zPos));
+                uv.push_back(glm::vec2(xSegment, ySegment));
+                normals.push_back(glm::vec3(xPos, yPos, zPos));
+            }
+        }
+
+        bool oddRow = false;
+        for (unsigned int y = 0; y < Y_SEGMENTS; ++y)
+        {
+            if (!oddRow) // even rows: y == 0, y == 2; and so on
+            {
+                for (unsigned int x = 0; x <= X_SEGMENTS; ++x)
+                {
+                    indices.push_back(y * (X_SEGMENTS + 1) + x);
+                    indices.push_back((y + 1) * (X_SEGMENTS + 1) + x);
+                }
+            }
+            else
+            {
+                for (int x = X_SEGMENTS; x >= 0; --x)
+                {
+                    indices.push_back((y + 1) * (X_SEGMENTS + 1) + x);
+                    indices.push_back(y * (X_SEGMENTS + 1) + x);
+                }
+            }
+            oddRow = !oddRow;
+        }
+        indexCount = static_cast<unsigned int>(indices.size());
+
+        std::vector<float> data;
+        for (unsigned int i = 0; i < positions.size(); ++i)
+        {
+            data.push_back(positions[i].x);
+            data.push_back(positions[i].y);
+            data.push_back(positions[i].z);
+            if (normals.size() > 0)
+            {
+                data.push_back(normals[i].x);
+                data.push_back(normals[i].y);
+                data.push_back(normals[i].z);
+            }
+            if (uv.size() > 0)
+            {
+                data.push_back(uv[i].x);
+                data.push_back(uv[i].y);
+            }
+        }
+        glBindVertexArray(sphereVAO);
+        glBindBuffer(GL_ARRAY_BUFFER, vbo);
+        glBufferData(GL_ARRAY_BUFFER, data.size() * sizeof(float), &data[0], GL_STATIC_DRAW);
+        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo);
+        glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices.size() * sizeof(unsigned int), &indices[0], GL_STATIC_DRAW);
+        unsigned int stride = (3 + 2 + 3) * sizeof(float);
+        glEnableVertexAttribArray(0);
+        glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, stride, (void*)0);
+        glEnableVertexAttribArray(1);
+        glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, stride, (void*)(3 * sizeof(float)));
+        glEnableVertexAttribArray(2);
+        glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, stride, (void*)(6 * sizeof(float)));
+
+    }
+
+    glBindVertexArray(sphereVAO);
+    glDrawElements(GL_TRIANGLE_STRIP, indexCount, GL_UNSIGNED_INT, 0);
+}
+
+
+
+
 void Renderer::Render(Scene& scene)
 {
-    static RenderPass currentPass = RenderPass::SKYBOX;
+   
-
     glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
     glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
 
@@ -105,7 +222,7 @@ void Renderer::Render(Scene& scene)
     auto view = scene.MainCamera.GetViewMatrix();
     auto model = glm::mat4(1.0f);   
 
-    std::cout << "SKYBOX PASS!" << std::endl;
+    // Skybox 
     glDepthMask(GL_FALSE);
     Shader shader = shaders.at(static_cast<int>(RenderPass::SKYBOX));
 
@@ -124,7 +241,7 @@ void Renderer::Render(Scene& scene)
     glDepthMask(GL_TRUE);
 
 
-    std::cout << "DEFAULT PASS!" << std::endl;
+    // Phong lighting
     shader = shaders.at(static_cast<int>(RenderPass::DEFAULT));
 
     shader.use();
@@ -135,7 +252,7 @@ void Renderer::Render(Scene& scene)
     scene.skybox.Bind();
     glActiveTexture(GL_TEXTURE0);
 
-
+    model = glm::translate(model, glm::vec3(20.0f, 0.0f, 0.0f));
     shader.setMat4("model", model);
     shader.setMat4("view", view);
     shader.setMat4("projection", projection);
@@ -143,6 +260,59 @@ void Renderer::Render(Scene& scene)
         entity.Draw(shader);
     }
     scene.skybox.Unbind();
+    
+
+    // PBR 
+    shader = shaders.at(static_cast<int>(RenderPass::PBR));
+
+    shader.use();
+    shader.setVec3("albedo", glm::vec3(0.5f, 0.0f, 0.0f));
+    shader.setFloat("ao", 1.0f);
+    shader.setMat4("projection", projection);
+    view = scene.MainCamera.GetViewMatrix();
+    shader.setMat4("view", view);
+    shader.setVec3("camPos", scene.MainCamera.Position);
+
+    model = glm::mat4(1.0f);
+    for (int row = 0; row < nrRows; ++row) {
+        shader.setFloat("metallic", (float)row / (float)nrRows);
+        for (int col = 0; col < nrColumns; ++col) {
+
+            shader.setFloat("roughness", glm::clamp((float)col / (float)nrColumns, 0.05f, 1.0f));
+
+            model = glm::mat4(1.0f);
+            model = glm::translate(model, glm::vec3(
+                (col - (nrColumns / 2)) * spacing,
+                (row - (nrRows / 2)) * spacing,
+                0.0f
+            ));
+
+            shader.setMat4("model", model);
+            shader.setMat3("normalMatrix", glm::transpose(glm::inverse(glm::mat3(model))));
+            renderSphere();
+
+        }
+    }
+
+    // Render light source
+    for (unsigned int i = 0; i < sizeof(lightPositions) / sizeof(lightPositions[0]); ++i) {
+        glm::vec3 newPos = lightPositions[i] + glm::vec3(sin(glfwGetTime() * 5.0) * 5.0, 0.0, 0.0);
+        newPos = lightPositions[i];
+        shader.setVec3("lightPositions[" + std::to_string(i)+"]", newPos);
+        shader.setVec3("lightColors[" + std::to_string(i) + "]", lightColors[i]);
+
+        model = glm::mat4(1.0f);
+        model = glm::translate(model, newPos);
+        model = glm::scale(model, glm::vec3(0.5f));
+        shader.setMat4("model", model);
+        shader.setMat3("normalMatrix", glm::transpose(glm::inverse(glm::mat3(model))));
+
+        renderSphere();
+    }
+
+
+
+
 
     /*
     Shader OutlineShader;

src/main.cpp

@@ -53,6 +53,8 @@ public:
       scene.MainCamera = Camera(glm::vec3(0.0f, 0.0f, 8.0f));
 
 
+
+
       std::vector<std::string> faces = {
           "../Textures/skybox/right.jpg",
           "../Textures/skybox/left.jpg",
@@ -67,7 +69,8 @@ public:
       renderer.resize(WIDTH, HEIGHT);
       renderer.Setup();
 
-     
+
+
 
       //glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
       while(!window.shouldClose())