【学习日志】2022.11.03 LearnOpenGL----DAY1

Draw Cube

#include <iostream>
#include <glad/gl.h>
#define GLFW_INCLUDE_NONE
#include <GLFW/glfw3.h>
 
#include <glm/glm.hpp>
#include<glm/gtc/matrix_transform.hpp>
#include<glm/gtx/transform2.hpp>
#include<glm/gtx/euler_angles.hpp>
 
#include <stdlib.h>
#include <stdio.h>
 
#include "VertexData.h"
#include "ShaderSource.h"
 
using namespace std;
 
static void error_callback(int error, const char* description)
{
    fprintf(stderr, "Error: %s\n", description);
}
 
GLFWwindow* window;
GLuint vertex_shader, fragment_shader, program;
GLint mvp_location, vpos_location, vcol_location;
 
//初始化OpenGL
void init_opengl()
{
    cout<<"init opengl"<<endl;
 
    //设置错误回调
    glfwSetErrorCallback(error_callback);
 
    if (!glfwInit())
        exit(EXIT_FAILURE);
 
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 2);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);
 
    //创建窗口
    window = glfwCreateWindow(960, 640, "Simple example", NULL, NULL);
    if (!window)
    {
        glfwTerminate();
        exit(EXIT_FAILURE);
    }
 
    glfwMakeContextCurrent(window);
    gladLoadGL(glfwGetProcAddress);
    glfwSwapInterval(1);
 
 
}
 
//编译、链接Shader
void compile_shader()
{
    //创建顶点Shader
    vertex_shader = glCreateShader(GL_VERTEX_SHADER);
    //指定Shader源码
    glShaderSource(vertex_shader, 1, &vertex_shader_text, NULL);
    //编译Shader
    glCompileShader(vertex_shader);
    //获取编译结果
    GLint compile_status=GL_FALSE;
    glGetShaderiv(vertex_shader, GL_COMPILE_STATUS, &compile_status);
    if (compile_status == GL_FALSE)
    {
        GLchar message[256];
        glGetShaderInfoLog(vertex_shader, sizeof(message), 0, message);
        cout<<"compile vs error:"<<message<<endl;
    }
 
    //创建片段Shader
    fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
    //指定Shader源码
    glShaderSource(fragment_shader, 1, &fragment_shader_text, NULL);
    //编译Shader
    glCompileShader(fragment_shader);
    //获取编译结果
    compile_status=GL_FALSE;
    glGetShaderiv(fragment_shader, GL_COMPILE_STATUS, &compile_status);
    if (compile_status == GL_FALSE)
    {
        GLchar message[256];
        glGetShaderInfoLog(fragment_shader, sizeof(message), 0, message);
        cout<<"compile fs error:"<<message<<endl;
    }
 
 
    //创建GPU程序
    program = glCreateProgram();
    //附加Shader
    glAttachShader(program, vertex_shader);
    glAttachShader(program, fragment_shader);
    //Link
    glLinkProgram(program);
    //获取编译结果
    GLint link_status=GL_FALSE;
    glGetProgramiv(program, GL_LINK_STATUS, &link_status);
    if (link_status == GL_FALSE)
    {
        GLchar message[256];
        glGetProgramInfoLog(program, sizeof(message), 0, message);
        cout<<"link error:"<<message<<endl;
    }
}
 
int main(void)
{
    init_opengl();
 
    compile_shader();
 
    //获取shader属性ID
    mvp_location = glGetUniformLocation(program, "u_mvp");
    vpos_location = glGetAttribLocation(program, "a_pos");
    vcol_location = glGetAttribLocation(program, "a_color");
 
    while (!glfwWindowShouldClose(window))
    {
        float ratio;
        int width, height;
        glm::mat4 model,view, projection, mvp;
 
        //获取画面宽高
        glfwGetFramebufferSize(window, &width, &height);
        ratio = width / (float) height;
 
        glViewport(0, 0, width, height);
 
        glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
        glClearColor(49.f/255,77.f/255,121.f/255,1.f);
 
        //坐标系变换
        glm::mat4 trans = glm::translate(glm::vec3(0,0,0)); //不移动顶点坐标;
        static float rotate_eulerAngle=0.f;
        rotate_eulerAngle+=1;
        glm::mat4 rotation = glm::eulerAngleYXZ(glm::radians(rotate_eulerAngle), glm::radians(rotate_eulerAngle), glm::radians(rotate_eulerAngle)); //使用欧拉角旋转;
        glm::mat4 scale = glm::scale(glm::vec3(2.0f, 2.0f, 2.0f)); //缩放;
        model = trans*scale*rotation;
 
        view = glm::lookAt(glm::vec3(0, 0, 10), glm::vec3(0, 0,0), glm::vec3(0, 1, 0));
 
        projection=glm::perspective(glm::radians(60.f),ratio,1.f,1000.f);
 
        mvp=projection*view*model;
 
        //指定GPU程序(就是指定顶点着色器、片段着色器)
        glUseProgram(program);
        glEnable(GL_DEPTH_TEST);
        glEnable(GL_CULL_FACE);//开启背面剔除
 
        //启用顶点Shader属性(a_pos)，指定与顶点坐标数据进行关联
        glEnableVertexAttribArray(vpos_location);
        glVertexAttribPointer(vpos_location, 3, GL_FLOAT, false, sizeof(glm::vec3), kPositions);
 
        //启用顶点Shader属性(a_color)，指定与顶点颜色数据进行关联
        glEnableVertexAttribArray(vcol_location);
        glVertexAttribPointer(vcol_location, 3, GL_FLOAT, false, sizeof(glm::vec4), kColors);
 
        //上传mvp矩阵
        glUniformMatrix4fv(mvp_location, 1, GL_FALSE, &mvp[0][0]);
        //上传顶点数据并进行绘制
        glDrawArrays(GL_TRIANGLES, 0, 6*6);
 
        glfwSwapBuffers(window);
        glfwPollEvents();
    }
 
    glfwDestroyWindow(window);
 
    glfwTerminate();
    exit(EXIT_SUCCESS);
}