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#pragma once
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#ifndef MESH_H
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#define MESH_H
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#include <glad/glad.h>
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#include <glm/glm.hpp>
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#include <glm/gtc/matrix_transform.hpp>
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#include <myShader.h>
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#include <string>
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#include <vector>
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using namespace std;
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#define MAX_BONE_INFLUENCE 4
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struct Vertex {
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        glm::vec3 Position;
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        glm::vec3 Normal;
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        glm::vec3 TexCoords;
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        glm::vec3 Tangent;//解析法线贴图
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        glm::vec3 Bitangent;//解析法线贴图
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        int m_BoneIDs[MAX_BONE_INFLUENCE];//骨骼动画
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        float m_Weights[MAX_BONE_INFLUENCE];//骨骼动画
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};
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struct Texture {
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        unsigned int id;//根据路径加载图片，使用glGenTexture获得ID
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        string type;
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        string path;//从mMaterials中的材质对象中解析出来的纹理图片路径
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};
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class Mesh {
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public:
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        //网格数据
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        vector<Vertex> vertices;
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        vector<Texture> textures;
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        vector<unsigned int> indices;
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        unsigned int VAO;
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        //构造函数
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        Mesh(vector<Vertex> vertices, vector<Texture> textures, vector<unsigned int> indices) {
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                //数据存储
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                this->vertices = vertices;
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                this->textures = textures;
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                this->indices = indices;
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                //数据传递
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                setupMesh();
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        }
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        void Draw(Shader& shader) {
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                unsigned int diffuseNr = 1;//漫反射贴图的编号
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                unsigned int specularNr = 1;//镜面反射贴图的编号
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                unsigned int normalNr = 1;//法线贴图的编号
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                unsigned int heightNr = 1;//高度图的编号
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                //完成纹理数据的设置和绑定
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                for (unsigned int i = 0; i < textures.size(); i++) {//遍历所有贴图，可能包含漫反射贴图，镜面反射贴图或是其他贴图，需要根据type判断
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                        //激活当前贴图对应的纹理单元
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                        glActiveTexture(GL_TEXTURE0 + i);
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                        string number;
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                        string name = textures[i].type;
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                        if (name == "texture_diffuse") {
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                                number = to_string(diffuseNr++);
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                        }
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                        else if (name == "texture_specular") {
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                                number = to_string(specularNr++);
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                        }
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                        else if (name == "texture_normal") {
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                                number = to_string(normalNr++);
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                        }
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                        else if (name == "tetxure_height") {
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                                number = to_string(heightNr++);
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                        }
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                        //获取Shader中这个uniform变量的位置
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                        int textureLoc = glGetUniformLocation(shader.ID, (name + number).c_str());
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                        //告诉Shader这个sampler2D指向第几个纹理单元
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                        glUniform1i(textureLoc, i);
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                        //当前纹理单元绑定第几号纹理
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                        glBindTexture(GL_TEXTURE_2D, textures[i].id);
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                }
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                //绘制网格
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                glBindVertexArray(VAO);
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                //告诉GPU从EBO缓冲中哪里开始取索引，取多少个，每个索引的数据类型是什么，取了之后怎么画
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                glDrawElements(GL_TRIANGLES, static_cast<unsigned int>(indices.size()), GL_UNSIGNED_INT, 0);
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                glBindVertexArray(0);//解绑，不一定必要（因为绘制物体前都会先绑定这个物体的VAO，但最好加上）
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                glActiveTexture(0);//跟上边解绑一样，使所有数据结构回到初始时的状态
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        }
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private:
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        unsigned int VBO, EBO;
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        void setupMesh() {
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                //生成缓冲区
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                glGenVertexArrays(1, &VAO);
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                glGenBuffers(1, &VBO);
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                glGenBuffers(1, &EBO);
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                //绑定VAO
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                glBindVertexArray(VAO);
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                //生成VBO和EBO缓冲并传递数据
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                glBindBuffer(GL_ARRAY_BUFFER, VBO);
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                glBufferData(GL_ARRAY_BUFFER, vertices.size() * sizeof(Vertex), &vertices[0], GL_STATIC_DRAW);
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                glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
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                glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices.size() * sizeof(unsigned int), &indices[0], GL_STATIC_DRAW);
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                //设置VBO的读取规则
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                //Position
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                glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)0);
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                glEnableVertexAttribArray(0);
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                //Normal
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                glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, Normal));
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                glEnableVertexAttribArray(1);
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                //TexCoords
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                glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, TexCoords));
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                glEnableVertexAttribArray(2);
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                //Tangent
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                glVertexAttribPointer(3, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, Tangent));
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                glEnableVertexAttribArray(3);
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                //Bitangent
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                glVertexAttribPointer(4, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, Bitangent));
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                glEnableVertexAttribArray(4);
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                //m_BoneIDs
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                glVertexAttribPointer(5, 4, GL_INT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, m_BoneIDs));
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                glEnableVertexAttribArray(5);
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                //m_Weights
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                glVertexAttribPointer(6, 4, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, m_Weights));
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                glEnableVertexAttribArray(6);
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                //解绑
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                glBindVertexArray(0);
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        }
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};
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#endif

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void Draw(Shader &shader){
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    int diffuseIndex=0;
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    int specularIndex=0;
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    int normalIndex=0;
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    int heightIndex=0;
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    for(int i=0;i<textures.size();i++){
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        glActiveTexture(GL_TEXTURE0+i);
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        string name=textures[i].type;
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        int idx=0;
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        if(name=="texture_diffuse"){
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            idx=diffuseIndex++;
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        }else if(name=="texture_specular"){
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            idx=specularIndex++;
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        }else if(name=="tetxure_normal"){
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            idx=normalIndex++;
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        }else if(name=="texture_height"){
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            idx=heightIndex++;
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        }
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        string uniformName="material."+name+"["+to_string(idx)+"]";
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        int textureLoc=glGetUniformLocation(shader.ID,uniformName.c_str());
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        glUniform1i(textureLoc,i);
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        glBindTexture(GL_TEXTURE_2D,textures[i].id);
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        glBindVertexArray(VAO);
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        glDrawElements(GL_TRIANGLES,static_cast<unsigned int>(indices.size()),GL_UNSIGNED_INT,0);
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        glBindVertexArray(0);
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    }
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}