112 lines
4.4 KiB
Plaintext
112 lines
4.4 KiB
Plaintext
#include <iostream>
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// GLEW
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#define GLEW_STATIC
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#include <GL/glew.h>
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// GLFW
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#include <GLFW/glfw3.h>
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// Other includes
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#include "shader.h"
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// Function prototypes
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void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode);
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// Window dimensions
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const GLuint WIDTH = 800, HEIGHT = 600;
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// The MAIN function, from here we start the application and run the game loop
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int main()
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{
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// Init GLFW
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glfwInit();
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// Set all the required options for GLFW
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glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
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glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
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glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
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glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);
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// Create a GLFWwindow object that we can use for GLFW's functions
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GLFWwindow* window = glfwCreateWindow(WIDTH, HEIGHT, "LearnOpenGL", nullptr, nullptr);
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glfwMakeContextCurrent(window);
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// Set the required callback functions
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glfwSetKeyCallback(window, key_callback);
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// Set this to true so GLEW knows to use a modern approach to retrieving function pointers and extensions
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glewExperimental = GL_TRUE;
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// Initialize GLEW to setup the OpenGL Function pointers
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glewInit();
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// Define the viewport dimensions
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glViewport(0, 0, WIDTH, HEIGHT);
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//读取shader文件，并编译，见shader.h代码
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Shader ourShader("shader.vs", "shader.frag");
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// 一维数组，每六个代表一个顶点属性，前三个代表位置属性，后三个代表颜色属性
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GLfloat vertices[] = {
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// Positions // Colors
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0.5f, -0.5f, 0.0f, 1.0f, 0.0f, 0.0f, // Bottom Right
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-0.5f, -0.5f, 0.0f, 0.0f, 1.0f, 0.0f, // Bottom Left
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0.0f, 0.5f, 0.0f, 0.0f, 0.0f, 1.0f // Top
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};
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GLuint VBO, VAO;//声明顶点缓冲，声明顶点数组用于管理顶点数据
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glGenVertexArrays(1, &VAO);//创建顶点数组，返回一个独一无二的整数，标识数组
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glGenBuffers(1, &VBO);//创建顶点缓冲，返回一个独一无二的整数，标识缓冲区
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glBindVertexArray(VAO);//绑定顶点数组
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glBindBuffer(GL_ARRAY_BUFFER, VBO);//绑定顶点缓冲
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//指定顶点数组的数据源为vertices，第四个参数代表显卡如何管理给定的数据，GL_STATIC_DRWA代表几乎不会改变
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glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
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// 指定顶点属性的解析方式。即，如何从顶点缓冲获取相应的顶点属性和相应的颜色属性。或者说，顶点着色器中如何知道去哪个顶点属性分量重着色呢
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//对每一个顶点而言，属性有2种，一是位置属性，而是颜色属性，因此每六个浮点数决定了一个顶点的位置和颜色
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//顶点着色器中使用layout(location = 0)定义了position顶点属性的位置值(Location)，因此第一个参数，代表属性分量的索引
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//参数二：顶点位置属性的维度，参数三：属性向量的数据类型，参数四:是否标准化；参数五，顶点位置属性的总字节长度，参数六：在缓冲数组中的偏移量，即起始位置
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glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat), (GLvoid*)0);
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glEnableVertexAttribArray(0);//启用属性0，因为默认是禁用的
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// 参数一，对应顶点着色器中的layout (location = 1) in vec3 color;参数六：说明颜色属性的偏移量在三个浮点数后，与上文vertices一致
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glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat), (GLvoid*)(3 * sizeof(GLfloat)));
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glEnableVertexAttribArray(1);//启用属性1.
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//顶点数组对象(Vertex Array Object, VAO)的好处就是，当配置顶点属性指针时，你只需要将上面的代码调用执行一次，之后再绘制物体的时候只需要绑定相应的VAO就行了。如下文循环中的绑定再解绑
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glBindVertexArray(0); // 解绑 VAO
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// Game loop
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while (!glfwWindowShouldClose(window))
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{
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// 检查事件，调用相应的回调函数，如下文的key_callback函数
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glfwPollEvents();
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// Render
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// Clear the colorbuffer
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glClearColor(0.2f, 0.3f, 0.3f, 1.0f);//渲染颜色到后台缓冲
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glClear(GL_COLOR_BUFFER_BIT);//清除前台缓冲
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// Draw the triangle
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ourShader.Use();//启用着色器程序
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glBindVertexArray(VAO);//每次循环都调用，绑定函数绑定VAO
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glDrawArrays(GL_TRIANGLES, 0, 3);
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glBindVertexArray(0);//解绑
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// Swap the screen buffers
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glfwSwapBuffers(window);
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}
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// Properly de-allocate all resources once they've outlived their purpose
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glDeleteVertexArrays(1, &VAO);
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glDeleteBuffers(1, &VBO);
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// Terminate GLFW, clearing any resources allocated by GLFW.
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glfwTerminate();
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return 0;
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}
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// Is called whenever a key is pressed/released via GLFW
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void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode)
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{
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if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
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glfwSetWindowShouldClose(window, GL_TRUE);
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}
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