Added Normal Maps

Engine/engine.cpp

@@ -1,6 +1,8 @@
 #include "Engine.h"
 #include <iostream>
 #include <glm/gtc/type_ptr.hpp>
+#define STB_IMAGE_IMPLEMENTATION
+#include "stb_image.h"
 
 // Static member definitions.
 GLFWwindow* Engine::window = nullptr;
@@ -14,6 +16,8 @@ float Engine::rotationAngle = 0.0f;
 int Engine::fbWidth = 640;
 int Engine::fbHeight = 400;
 
+GLuint normalMapTexture = 0; // Global texture for the normal map
+
 bool Engine::Init() {
     if (!glfwInit()) {
         std::cout << "Failed to initialize GLFW\n";
@@ -45,7 +49,7 @@ bool Engine::Init() {
     glGenFramebuffers(1, &framebuffer);
     ResizeFramebuffer(fbWidth, fbHeight);
 
-    // Setup cube geometry and shaders.
+    // Setup cube geometry, shaders, and load normal map.
     if (!SetupScene()) {
         std::cout << "Failed to set up scene\n";
         return false;
@@ -70,10 +74,10 @@ void Engine::ResizeFramebuffer(int width, int height) {
     int newWidth = width;
     int newHeight = height;
     if (currentAspect > targetAspect) {
-        // The viewport is too wide: adjust width.
+        // Too wide: adjust width.
         newWidth = static_cast<int>(height * targetAspect);
     } else if (currentAspect < targetAspect) {
-        // The viewport is too tall: adjust height.
+        // Too tall: adjust height.
         newHeight = static_cast<int>(width / targetAspect);
     }
     
@@ -111,7 +115,6 @@ void Engine::ResizeFramebuffer(int width, int height) {
     glBindFramebuffer(GL_FRAMEBUFFER, 0);
 }
 
-
 GLuint Engine::CompileShader(const char* vertexSrc, const char* fragmentSrc) {
     GLuint vertexShader = glCreateShader(GL_VERTEX_SHADER);
     glShaderSource(vertexShader, 1, &vertexSrc, nullptr);
@@ -151,56 +154,57 @@ GLuint Engine::CompileShader(const char* vertexSrc, const char* fragmentSrc) {
 }
 
 bool Engine::SetupScene() {
-    // Cube vertices: positions and normals.
+    // Updated cube vertices: each vertex has:
+    // position (3), normal (3), texcoord (2), tangent (3) = 11 floats per vertex.
     float vertices[] = {
-        // positions         // normals
+        // Front face (normal: 0,0,1), tangent: (1,0,0)
-        // Front face
+        // positions         normals       texcoords   tangent
-        -0.5f, -0.5f,  0.5f,  0, 0, 1,
+        -0.5f, -0.5f,  0.5f,  0,0,1,       0,0,       1,0,0,
-         0.5f, -0.5f,  0.5f,  0, 0, 1,
+         0.5f, -0.5f,  0.5f,  0,0,1,       1,0,       1,0,0,
-         0.5f,  0.5f,  0.5f,  0, 0, 1,
+         0.5f,  0.5f,  0.5f,  0,0,1,       1,1,       1,0,0,
-         0.5f,  0.5f,  0.5f,  0, 0, 1,
+         0.5f,  0.5f,  0.5f,  0,0,1,       1,1,       1,0,0,
-        -0.5f,  0.5f,  0.5f,  0, 0, 1,
+        -0.5f,  0.5f,  0.5f,  0,0,1,       0,1,       1,0,0,
-        -0.5f, -0.5f,  0.5f,  0, 0, 1,
+        -0.5f, -0.5f,  0.5f,  0,0,1,       0,0,       1,0,0,
 
-        // Back face
+        // Back face (normal: 0,0,-1), tangent: (-1,0,0)
-        -0.5f, -0.5f, -0.5f,  0, 0, -1,
+         0.5f, -0.5f, -0.5f,  0,0,-1,      0,0,      -1,0,0,
-         0.5f, -0.5f, -0.5f,  0, 0, -1,
+        -0.5f, -0.5f, -0.5f,  0,0,-1,      1,0,      -1,0,0,
-         0.5f,  0.5f, -0.5f,  0, 0, -1,
+        -0.5f,  0.5f, -0.5f,  0,0,-1,      1,1,      -1,0,0,
-         0.5f,  0.5f, -0.5f,  0, 0, -1,
+        -0.5f,  0.5f, -0.5f,  0,0,-1,      1,1,      -1,0,0,
-        -0.5f,  0.5f, -0.5f,  0, 0, -1,
+         0.5f,  0.5f, -0.5f,  0,0,-1,      0,1,      -1,0,0,
-        -0.5f, -0.5f, -0.5f,  0, 0, -1,
+         0.5f, -0.5f, -0.5f,  0,0,-1,      0,0,      -1,0,0,
 
-        // Left face
+        // Left face (normal: -1,0,0), tangent: (0,0,-1)
-        -0.5f,  0.5f,  0.5f, -1, 0, 0,
+        -0.5f, -0.5f, -0.5f, -1,0,0,       0,0,       0,0,-1,
-        -0.5f,  0.5f, -0.5f, -1, 0, 0,
+        -0.5f, -0.5f,  0.5f, -1,0,0,       1,0,       0,0,-1,
-        -0.5f, -0.5f, -0.5f, -1, 0, 0,
+        -0.5f,  0.5f,  0.5f, -1,0,0,       1,1,       0,0,-1,
-        -0.5f, -0.5f, -0.5f, -1, 0, 0,
+        -0.5f,  0.5f,  0.5f, -1,0,0,       1,1,       0,0,-1,
-        -0.5f, -0.5f,  0.5f, -1, 0, 0,
+        -0.5f,  0.5f, -0.5f, -1,0,0,       0,1,       0,0,-1,
-        -0.5f,  0.5f,  0.5f, -1, 0, 0,
+        -0.5f, -0.5f, -0.5f, -1,0,0,       0,0,       0,0,-1,
 
-        // Right face
+        // Right face (normal: 1,0,0), tangent: (0,0,1)
-         0.5f,  0.5f,  0.5f,  1, 0, 0,
+         0.5f, -0.5f,  0.5f,  1,0,0,       0,0,       0,0,1,
-         0.5f,  0.5f, -0.5f,  1, 0, 0,
+         0.5f, -0.5f, -0.5f,  1,0,0,       1,0,       0,0,1,
-         0.5f, -0.5f, -0.5f,  1, 0, 0,
+         0.5f,  0.5f, -0.5f,  1,0,0,       1,1,       0,0,1,
-         0.5f, -0.5f, -0.5f,  1, 0, 0,
+         0.5f,  0.5f, -0.5f,  1,0,0,       1,1,       0,0,1,
-         0.5f, -0.5f,  0.5f,  1, 0, 0,
+         0.5f,  0.5f,  0.5f,  1,0,0,       0,1,       0,0,1,
-         0.5f,  0.5f,  0.5f,  1, 0, 0,
+         0.5f, -0.5f,  0.5f,  1,0,0,       0,0,       0,0,1,
 
-        // Top face
+        // Top face (normal: 0,1,0), tangent: (1,0,0)
-        -0.5f,  0.5f, -0.5f,  0, 1, 0,
+        -0.5f,  0.5f,  0.5f,  0,1,0,       0,0,       1,0,0,
-         0.5f,  0.5f, -0.5f,  0, 1, 0,
+         0.5f,  0.5f,  0.5f,  0,1,0,       1,0,       1,0,0,
-         0.5f,  0.5f,  0.5f,  0, 1, 0,
+         0.5f,  0.5f, -0.5f,  0,1,0,       1,1,       1,0,0,
-         0.5f,  0.5f,  0.5f,  0, 1, 0,
+         0.5f,  0.5f, -0.5f,  0,1,0,       1,1,       1,0,0,
-        -0.5f,  0.5f,  0.5f,  0, 1, 0,
+        -0.5f,  0.5f, -0.5f,  0,1,0,       0,1,       1,0,0,
-        -0.5f,  0.5f, -0.5f,  0, 1, 0,
+        -0.5f,  0.5f,  0.5f,  0,1,0,       0,0,       1,0,0,
 
-        // Bottom face
+        // Bottom face (normal: 0,-1,0), tangent: (1,0,0)
-        -0.5f, -0.5f, -0.5f,  0, -1, 0,
+        -0.5f, -0.5f, -0.5f,  0,-1,0,      0,0,       1,0,0,
-         0.5f, -0.5f, -0.5f,  0, -1, 0,
+         0.5f, -0.5f, -0.5f,  0,-1,0,      1,0,       1,0,0,
-         0.5f, -0.5f,  0.5f,  0, -1, 0,
+         0.5f, -0.5f,  0.5f,  0,-1,0,      1,1,       1,0,0,
-         0.5f, -0.5f,  0.5f,  0, -1, 0,
+         0.5f, -0.5f,  0.5f,  0,-1,0,      1,1,       1,0,0,
-        -0.5f, -0.5f,  0.5f,  0, -1, 0,
+        -0.5f, -0.5f,  0.5f,  0,-1,0,      0,1,       1,0,0,
-        -0.5f, -0.5f, -0.5f,  0, -1, 0
+        -0.5f, -0.5f, -0.5f,  0,-1,0,      0,0,       1,0,0
     };
 
     glGenVertexArrays(1, &cubeVAO);
@@ -209,11 +213,17 @@ bool Engine::SetupScene() {
     glBindBuffer(GL_ARRAY_BUFFER, cubeVBO);
     glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
     // Position attribute.
-    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0);
+    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 11 * sizeof(float), (void*)0);
     glEnableVertexAttribArray(0);
     // Normal attribute.
-    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)(3 * sizeof(float)));
+    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 11 * sizeof(float), (void*)(3 * sizeof(float)));
     glEnableVertexAttribArray(1);
+    // Texcoord attribute.
+    glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 11 * sizeof(float), (void*)(6 * sizeof(float)));
+    glEnableVertexAttribArray(2);
+    // Tangent attribute.
+    glVertexAttribPointer(3, 3, GL_FLOAT, GL_FALSE, 11 * sizeof(float), (void*)(8 * sizeof(float)));
+    glEnableVertexAttribArray(3);
     glBindVertexArray(0);
 
     // Vertex shader source.
@@ -221,6 +231,8 @@ bool Engine::SetupScene() {
         #version 330 core
         layout(location = 0) in vec3 aPos;
         layout(location = 1) in vec3 aNormal;
+        layout(location = 2) in vec2 aTexCoords;
+        layout(location = 3) in vec3 aTangent;
 
         uniform mat4 model;
         uniform mat4 view;
@@ -228,40 +240,57 @@ bool Engine::SetupScene() {
 
         out vec3 FragPos;
         out vec3 Normal;
+        out vec2 TexCoords;
+        out vec3 Tangent;
 
         void main() {
             FragPos = vec3(model * vec4(aPos, 1.0));
             Normal = mat3(transpose(inverse(model))) * aNormal;
+            TexCoords = aTexCoords;
+            Tangent = mat3(model) * aTangent; 
             gl_Position = projection * view * vec4(FragPos, 1.0);
         }
     )";
 
-    // Fragment shader source with red light.
+    // Fragment shader source with normal mapping.
     const char* fragmentShaderSrc = R"(
         #version 330 core
         out vec4 FragColor;
 
         in vec3 FragPos;
         in vec3 Normal;
+        in vec2 TexCoords;
+        in vec3 Tangent;
 
         uniform vec3 lightPos;
         uniform vec3 viewPos;
+        uniform sampler2D normalMap;
 
         void main() {
+            // Obtain the normal from the normal map in range [0,1] and remap to [-1,1].
+            vec3 normMap = texture(normalMap, TexCoords).rgb;
+            normMap = normalize(normMap);
+            
+            // Calculate TBN matrix. For simplicity, compute bitangent as cross(normal, tangent).
+            vec3 N = normalize(Normal);
+            vec3 T = normalize(Tangent);
+            vec3 B = normalize(cross(N, T));
+            mat3 TBN = mat3(T, B, N);
+            vec3 perturbedNormal = normalize(TBN * normMap);
+
             // Ambient.
-            float ambientStrength = 0.3;
+            float ambientStrength = 0.5;
             vec3 ambient = ambientStrength * vec3(1.0, 0.0, 1.0);
 
             // Diffuse.
-            vec3 norm = normalize(Normal);
             vec3 lightDir = normalize(lightPos - FragPos);
-            float diff = max(dot(norm, lightDir), 0.0);
+            float diff = max(dot(perturbedNormal, lightDir), 0.0);
-            vec3 diffuse = diff * vec3(1.0, 0.0, 0.0);
+            vec3 diffuse = diff * vec3(1.0, 1.0, 1.0);
 
             // Specular.
-            float specularStrength = 0.5;
+            float specularStrength = 0.2;
             vec3 viewDir = normalize(viewPos - FragPos);
-            vec3 reflectDir = reflect(-lightDir, norm);
+            vec3 reflectDir = reflect(-lightDir, perturbedNormal);
             float spec = pow(max(dot(viewDir, reflectDir), 0.0), 32);
             vec3 specular = specularStrength * spec * vec3(1.0);
 
@@ -274,6 +303,30 @@ bool Engine::SetupScene() {
     if (shaderProgram == 0) {
         return false;
     }
+
+    // Load normal map from "./normal.png"
+    int texWidth, texHeight, texChannels;
+    unsigned char* data = stbi_load("./normal.jpg", &texWidth, &texHeight, &texChannels, 0);
+    if (!data) {
+        std::cout << "Failed to load normal map." << std::endl;
+        return false;
+    }
+    glGenTextures(1, &normalMapTexture);
+    glBindTexture(GL_TEXTURE_2D, normalMapTexture);
+    GLenum format = (texChannels == 3) ? GL_RGB : GL_RGBA;
+    glTexImage2D(GL_TEXTURE_2D, 0, format, texWidth, texHeight, 0, format, GL_UNSIGNED_BYTE, data);
+    glGenerateMipmap(GL_TEXTURE_2D);
+    // Set texture parameters.
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+    stbi_image_free(data);
+
+    // Bind the normal map to texture unit 1.
+    glUseProgram(shaderProgram);
+    glUniform1i(glGetUniformLocation(shaderProgram, "normalMap"), 1);
+
     return true;
 }
 
@@ -295,6 +348,10 @@ ImTextureID Engine::RenderScene(const glm::mat4 &view, const glm::mat4 &projecti
 
     glUniform3f(glGetUniformLocation(shaderProgram, "lightPos"), 0.0f, 20.0f, 0.0f);
 
+    // Activate texture unit 1 and bind the normal map.
+    glActiveTexture(GL_TEXTURE1);
+    glBindTexture(GL_TEXTURE_2D, normalMapTexture);
+
     glBindVertexArray(cubeVAO);
     glDrawArrays(GL_TRIANGLES, 0, 36);
     glBindVertexArray(0);
@@ -313,6 +370,7 @@ void Engine::Shutdown() {
     glDeleteProgram(shaderProgram);
     glDeleteFramebuffers(1, &framebuffer);
     glDeleteTextures(1, &colorTexture);
+    glDeleteTextures(1, &normalMapTexture);
     glDeleteRenderbuffers(1, &depthRenderbuffer);
     glfwDestroyWindow(window);
     glfwTerminate();

Makefile

@@ -1,6 +1,6 @@
 # Compiler and flags
 CXX := g++
-CXXFLAGS := -std=c++20 -Wall -Wextra -O2 -I/c/msys64/mingw64/include -Ivendor/imgui-docking
+CXXFLAGS := -std=c++20 -Wall -Wextra -O2 -I/c/msys64/mingw64/include -Ivendor/imgui-docking -Ivendor/stb
 
 # Use this to link against the correct import lib
 LDFLAGS := -Llib -lglfw3 -lopengl32 -lglew32 -lglu32