ThreeLab/Engine/Components/ModelComponent.cpp

#include "ModelComponent.h"
#include "stb_image.h"
#include <iostream>

// Constructor: initialize material defaults, create default cube mesh, and load default textures.
ModelComponent::ModelComponent()
    : diffuseColor(1.0f, 1.0f, 1.0f),
      specularColor(1.0f, 1.0f, 1.0f),
      shininess(32.0f),
      VAO(0), VBO(0), EBO(0),
      diffuseTexture(0), normalTexture(0)
{
    // Clear any previous data.
    vertices.clear();
    indices.clear();

    // Create 24 vertices for a cube.
    // Front face (z = 0.5)
    Vertex v;
    v.Normal = glm::vec3(0, 0, 1);
    v.Tangent = glm::vec3(1, 0, 0);
    // Top-left
    v.Position = glm::vec3(-0.5f,  0.5f, 0.5f);
    v.TexCoords = glm::vec2(0.0f, 1.0f);
    vertices.push_back(v);
    // Bottom-left
    v.Position = glm::vec3(-0.5f, -0.5f, 0.5f);
    v.TexCoords = glm::vec2(0.0f, 0.0f);
    vertices.push_back(v);
    // Bottom-right
    v.Position = glm::vec3( 0.5f, -0.5f, 0.5f);
    v.TexCoords = glm::vec2(1.0f, 0.0f);
    vertices.push_back(v);
    // Top-right
    v.Position = glm::vec3( 0.5f,  0.5f, 0.5f);
    v.TexCoords = glm::vec2(1.0f, 1.0f);
    vertices.push_back(v);

    // Right face (x = 0.5)
    v.Normal = glm::vec3(1, 0, 0);
    v.Tangent = glm::vec3(0, 0, -1);
    // Top-left
    v.Position = glm::vec3(0.5f,  0.5f,  0.5f);
    v.TexCoords = glm::vec2(0.0f, 1.0f);
    vertices.push_back(v);
    // Bottom-left
    v.Position = glm::vec3(0.5f, -0.5f,  0.5f);
    v.TexCoords = glm::vec2(0.0f, 0.0f);
    vertices.push_back(v);
    // Bottom-right
    v.Position = glm::vec3(0.5f, -0.5f, -0.5f);
    v.TexCoords = glm::vec2(1.0f, 0.0f);
    vertices.push_back(v);
    // Top-right
    v.Position = glm::vec3(0.5f,  0.5f, -0.5f);
    v.TexCoords = glm::vec2(1.0f, 1.0f);
    vertices.push_back(v);

    // Back face (z = -0.5)
    v.Normal = glm::vec3(0, 0, -1);
    v.Tangent = glm::vec3(-1, 0, 0);
    // Top-left
    v.Position = glm::vec3( 0.5f,  0.5f, -0.5f);
    v.TexCoords = glm::vec2(0.0f, 1.0f);
    vertices.push_back(v);
    // Bottom-left
    v.Position = glm::vec3( 0.5f, -0.5f, -0.5f);
    v.TexCoords = glm::vec2(0.0f, 0.0f);
    vertices.push_back(v);
    // Bottom-right
    v.Position = glm::vec3(-0.5f, -0.5f, -0.5f);
    v.TexCoords = glm::vec2(1.0f, 0.0f);
    vertices.push_back(v);
    // Top-right
    v.Position = glm::vec3(-0.5f,  0.5f, -0.5f);
    v.TexCoords = glm::vec2(1.0f, 1.0f);
    vertices.push_back(v);

    // Left face (x = -0.5)
    v.Normal = glm::vec3(-1, 0, 0);
    v.Tangent = glm::vec3(0, 0, 1);
    // Top-left
    v.Position = glm::vec3(-0.5f,  0.5f, -0.5f);
    v.TexCoords = glm::vec2(0.0f, 1.0f);
    vertices.push_back(v);
    // Bottom-left
    v.Position = glm::vec3(-0.5f, -0.5f, -0.5f);
    v.TexCoords = glm::vec2(0.0f, 0.0f);
    vertices.push_back(v);
    // Bottom-right
    v.Position = glm::vec3(-0.5f, -0.5f,  0.5f);
    v.TexCoords = glm::vec2(1.0f, 0.0f);
    vertices.push_back(v);
    // Top-right
    v.Position = glm::vec3(-0.5f,  0.5f,  0.5f);
    v.TexCoords = glm::vec2(1.0f, 1.0f);
    vertices.push_back(v);

    // Top face (y = 0.5)
    v.Normal = glm::vec3(0, 1, 0);
    v.Tangent = glm::vec3(1, 0, 0);
    // Top-left
    v.Position = glm::vec3(-0.5f, 0.5f, -0.5f);
    v.TexCoords = glm::vec2(0.0f, 1.0f);
    vertices.push_back(v);
    // Bottom-left
    v.Position = glm::vec3(-0.5f, 0.5f,  0.5f);
    v.TexCoords = glm::vec2(0.0f, 0.0f);
    vertices.push_back(v);
    // Bottom-right
    v.Position = glm::vec3( 0.5f, 0.5f,  0.5f);
    v.TexCoords = glm::vec2(1.0f, 0.0f);
    vertices.push_back(v);
    // Top-right
    v.Position = glm::vec3( 0.5f, 0.5f, -0.5f);
    v.TexCoords = glm::vec2(1.0f, 1.0f);
    vertices.push_back(v);

    // Bottom face (y = -0.5)
    v.Normal = glm::vec3(0, -1, 0);
    v.Tangent = glm::vec3(1, 0, 0);
    // Top-left
    v.Position = glm::vec3(-0.5f, -0.5f,  0.5f);
    v.TexCoords = glm::vec2(0.0f, 1.0f);
    vertices.push_back(v);
    // Bottom-left
    v.Position = glm::vec3(-0.5f, -0.5f, -0.5f);
    v.TexCoords = glm::vec2(0.0f, 0.0f);
    vertices.push_back(v);
    // Bottom-right
    v.Position = glm::vec3( 0.5f, -0.5f, -0.5f);
    v.TexCoords = glm::vec2(1.0f, 0.0f);
    vertices.push_back(v);
    // Top-right
    v.Position = glm::vec3( 0.5f, -0.5f,  0.5f);
    v.TexCoords = glm::vec2(1.0f, 1.0f);
    vertices.push_back(v);

    // Define indices: 6 faces, 2 triangles per face, 3 indices per triangle.
    indices = {
        0,  1,  2,  0,  2,  3,        // Front face
        4,  5,  6,  4,  6,  7,        // Right face
        8,  9, 10,  8, 10, 11,        // Back face
        12, 13, 14, 12, 14, 15,        // Left face
        16, 17, 18, 16, 18, 19,        // Top face
        20, 21, 22, 20, 22, 23         // Bottom face
    };

    // Setup mesh with the new vertex/index data.
    SetupMesh();

    // Load default textures.
    if(!LoadDiffuseTexture("./assets/bricks.png")) {
         std::cout << "Warning: Failed to load default diffuse texture 'bricks.png'\n";
    }
    if(!LoadNormalTexture("./assets/normal.png")) {
         std::cout << "Warning: Failed to load default normal texture 'normal.png'\n";
    }
}

ModelComponent::~ModelComponent() {
    if(VAO) glDeleteVertexArrays(1, &VAO);
    if(VBO) glDeleteBuffers(1, &VBO);
    if(EBO) glDeleteBuffers(1, &EBO);
    if(diffuseTexture) glDeleteTextures(1, &diffuseTexture);
    if(normalTexture) glDeleteTextures(1, &normalTexture);
}

void ModelComponent::SetupMesh() {
    glGenVertexArrays(1, &VAO);
    glGenBuffers(1, &VBO);
    glGenBuffers(1, &EBO);
    
    glBindVertexArray(VAO);
    
    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glBufferData(GL_ARRAY_BUFFER, vertices.size() * sizeof(Vertex), &vertices[0], GL_STATIC_DRAW);
    
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices.size() * sizeof(GLuint), &indices[0], GL_STATIC_DRAW);
    
    // Vertex attributes:
    // Positions.
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)0);
    glEnableVertexAttribArray(0);
    // Normals.
    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, Normal));
    glEnableVertexAttribArray(1);
    // TexCoords.
    glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, TexCoords));
    glEnableVertexAttribArray(2);
    // Tangents.
    glVertexAttribPointer(3, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, Tangent));
    glEnableVertexAttribArray(3);
    
    glBindVertexArray(0);
}

// LoadDiffuseTexture loads a diffuse texture from file.
bool ModelComponent::LoadDiffuseTexture(const std::string &filepath) {
    int w, h, channels;
    unsigned char* data = stbi_load(filepath.c_str(), &w, &h, &channels, 0);
    if (!data) {
        std::cout << "Failed to load diffuse texture: " << filepath << std::endl;
        return false;
    }
    glGenTextures(1, &diffuseTexture);
    glBindTexture(GL_TEXTURE_2D, diffuseTexture);
    GLenum format = (channels == 3) ? GL_RGB : GL_RGBA;
    glTexImage2D(GL_TEXTURE_2D, 0, format, w, h, 0, format, GL_UNSIGNED_BYTE, data);
    glGenerateMipmap(GL_TEXTURE_2D);
    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);
    return true;
}

// LoadNormalTexture loads a normal map texture from file.
bool ModelComponent::LoadNormalTexture(const std::string &filepath) {
    int w, h, channels;
    unsigned char* data = stbi_load(filepath.c_str(), &w, &h, &channels, 0);
    if (!data) {
        std::cout << "Failed to load normal texture: " << filepath << std::endl;
        return false;
    }
    glGenTextures(1, &normalTexture);
    glBindTexture(GL_TEXTURE_2D, normalTexture);
    GLenum format = (channels == 3) ? GL_RGB : GL_RGBA;
    glTexImage2D(GL_TEXTURE_2D, 0, format, w, h, 0, format, GL_UNSIGNED_BYTE, data);
    glGenerateMipmap(GL_TEXTURE_2D);
    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);
    return true;
}

// Draw the mesh using its VAO.
void ModelComponent::Draw() {
    glBindVertexArray(VAO);
    glDrawElements(GL_TRIANGLES, static_cast<GLsizei>(indices.size()), GL_UNSIGNED_INT, 0);
    glBindVertexArray(0);
}