mesh.cpp

#include "mesh.h"

Mesh::Mesh(std::vector<Vertex> vertices, std::vector<unsigned int> indices, std::vector<Texture> textures){
    this->vertices = vertices;
    this->indices = indices;
    this->textures = textures;

    setupMesh();
}

Mesh::Mesh() : VAO(0), VBO(0), EBO(0) {
    // empty default constructor for dynamic/placeholder Mesh
}

void Mesh::setupMesh () {
    if (vertices.empty() || indices.empty()) return; // nothing to set up

    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.data(), GL_STATIC_DRAW);

    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices.size() * sizeof(unsigned int), indices.data(), GL_STATIC_DRAW);

    // vertex attributes...
    glEnableVertexAttribArray(0);
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)0);
    glEnableVertexAttribArray(1);
    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, Normal));
    glEnableVertexAttribArray(2);
    glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, TexCoords));

    glBindVertexArray(0);
}


void Mesh::Draw(Shader &shader) 
{
    const bool hasTextures = !textures.empty();
    shader.setBool("material.useTexture", hasTextures);

    unsigned int diffuseNr = 1;
    unsigned int specularNr = 1;
    for(unsigned int i = 0; i < textures.size(); i++)
    {
        glActiveTexture(GL_TEXTURE0 + i); // activate proper texture unit before binding
        // retrieve texture number (the N in diffuse_textureN)
        std::string number;
        std::string name = textures[i].type;
        if(name == "texture_diffuse")
            number = std::to_string(diffuseNr++);
        else if(name == "texture_specular")
            number = std::to_string(specularNr++);

        shader.setInt((name + number).c_str(), static_cast<int>(i));
        glBindTexture(GL_TEXTURE_2D, textures[i].id);
    }
    glActiveTexture(GL_TEXTURE0);

    // draw mesh
    glBindVertexArray(VAO);
    glDrawElements(GL_TRIANGLES, static_cast<GLsizei>(indices.size()), GL_UNSIGNED_INT, 0);
    glBindVertexArray(0);
}