MyCorn/mesh.cpp at main · Sakkana/MyCorn · GitHub

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#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;

    // 获得了所有的 obj 参数后设置顶点缓冲和属性指针
    setupMesh();
}

std::vector<Vertex> Mesh::get_vertices() { return this->vertices;  }

std::vector<unsigned int> Mesh::get_indices() { return this->indices;  }

std::vector<Texture> Mesh::get_textures() { return this->textures; }

void Mesh::Draw(Shader& shader)
{
    // bind appropriate textures
    unsigned int diffuseNr = 1;
    unsigned int specularNr = 1;
    unsigned int normalNr = 1;
    unsigned int heightNr = 1;

    for (unsigned int i = 0; i < textures.size(); i++)
    {
        glActiveTexture(GL_TEXTURE0 + i);

        // retrieve texture number (the N in diffuse_textureN)
        std::string number;

        if (textures[i].type == "texture_diffuse")  // 漫反射贴图
            number = std::to_string(diffuseNr++);
        else if (textures[i].type == "texture_specular")
            number = std::to_string(specularNr++); // transfer unsigned int to string
        else if (textures[i].type == "texture_normal")
            number = std::to_string(normalNr++); // transfer unsigned int to string
        else if (textures[i].type == "texture_height")
            number = std::to_string(heightNr++); // transfer unsigned int to string

        // now set the sampler to the correct texture unit
        glUniform1i(glGetUniformLocation(shader.ID, (textures[i].type + number).c_str()), i);

        // and finally bind the texture
        glBindTexture(GL_TEXTURE_2D, textures[i].id);
    }

    // draw mesh
    glBindVertexArray(VAO);
    glDrawElements(GL_TRIANGLES, static_cast<unsigned int>(indices.size()), GL_UNSIGNED_INT, 0);
    glBindVertexArray(0);   // 解绑

    // always good practice to set everything back to defaults once configured.
    glActiveTexture(GL_TEXTURE0);
}


void Mesh::setupMesh()
{
    // 顶点数组对象
    glGenVertexArrays(1, &VAO);
    glBindVertexArray(VAO);

    // 把【VBO顶点数据】放到内存中
    glGenBuffers(1, &VBO);
    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(Vertex) * vertices.size(), &vertices[0], GL_STATIC_DRAW);

    // 把【索引】放到内存中
    glGenBuffers(1, &EBO);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(unsigned int) * indices.size(), &indices[0], GL_STATIC_DRAW);

    // 顶点函数指针
    // vertex Positions
    glEnableVertexAttribArray(0);
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)0);

    // vertex normals
    glEnableVertexAttribArray(1);
    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, Normal));

    // vertex texture coords
    glEnableVertexAttribArray(2);
    glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, TexCoords));

    // vertex tangent
    glEnableVertexAttribArray(3);
    glVertexAttribPointer(3, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, Tangent));

    // vertex bitangent
    glEnableVertexAttribArray(4);
    glVertexAttribPointer(4, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, Bitangent));

    // ids
    glEnableVertexAttribArray(5);
    glVertexAttribIPointer(5, 4, GL_INT, sizeof(Vertex), (void*)offsetof(Vertex, m_BoneIDs));

    // weights
    glEnableVertexAttribArray(6);
    glVertexAttribPointer(6, 4, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, m_Weights));

    glBindVertexArray(0);
}