【OpenGL学习笔记】绘制三角形

     重点：使用VBO(顶点缓存对象)，VAO(顶点数组对象)，创建顶点着色器，片段着色器，绘制三角形。

#include
#include
#include

const char* cpVertexShader ="#version 330 core \n"//设置主版本号 启用核心模式
							"layout(location=0) in vec3 aPos;\n"//获取输入的位置变量。
							"void main()\n"
							"{\n"
							"     gl_Position = vec4(aPos.x,aPos.y,aPos.z,1.0);"//赋值给预定义变量 gl_Position
							"}\n;";//顶点着色器

const char* cpFragmentShader =  "#version 330 core\n"//设置主版本号 启用核心模式
								"out vec4 FragColor;"//输出的颜色
								"void main()"
								"{\n"
								"     FragColor = vec4(1.0f,0.5f,0.2f,1.0f);"
								"}\n";//片段着色器

float vertices[] = {
	-0.5f, -0.5f, 0.0f,
	0.5f, -0.5f, 0.0f,
	0.0f,  0.5f, 0.0f 
};

void framebuffer_size_callback(GLFWwindow* window, int width, int height);//回调函数，窗口改变大小，视口也调整
int main()
{
	glfwInit();//初始化GLFW
	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);//设置主版本号 3
	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);//设置次版本号 3
	glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);//设置使用核心模式

	GLFWwindow* window = glfwCreateWindow(800, 600, "LearnOpenGL", NULL, NULL);//创建窗口对象
	if (window == NULL)
	{
		std::cout << "Failed to create GLFW window" << std::endl;
		glfwTerminate();
		return -1;
	}

	glfwMakeContextCurrent(window);//设置为当前线程主上下文

	if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))//初始化GLAD（GLAD用来管理OpenGL的函数指针）
	{
		std::cout << "Failed to initialize GLAD" << std::endl;
		return -1;
	}

	glViewport(0, 0, 800, 600);//设置渲染窗口大小

	glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);//注册回调函数，刷新渲染窗口

	unsigned int VAO;
	glGenVertexArrays(1, &VAO);
	glBindVertexArray(VAO);//创建顶点数组对象

	unsigned int VBO;
	glGenBuffers(1, &VBO);
	glBindBuffer(GL_ARRAY_BUFFER, VBO);//创建顶点缓存对象
	glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);//设置顶点数据

	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);//设置顶点属性数据
	glEnableVertexAttribArray(0);//启用顶点属性，设置起始位置

	unsigned int vertexShader;
	vertexShader = glCreateShader(GL_VERTEX_SHADER);//创建顶点着色器

	glShaderSource(vertexShader, 1, &cpVertexShader, NULL);//绑定源代码到着色器程序
	glCompileShader(vertexShader);//编译着色器程序

	int success;
	char infoLog[512];
	glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);//检测是否创建成功
	if (!success)
	{
		glGetShaderInfoLog(vertexShader, 512, NULL, infoLog);
		std::cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog << std::endl;
	}

	unsigned int fragmentShader;
	fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);//创建片段着色器
	glShaderSource(fragmentShader, 1, &cpFragmentShader, NULL);//设置片段着色器源代码
	glCompileShader(fragmentShader);//编译着色器

	glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &success);//检测创建十分成功
	if (!success)
	{
		glGetShaderInfoLog(fragmentShader, 512, NULL, infoLog);
		std::cout << "ERROR::SHADER::FRAGMENT::COMPILATION_FAILED\n" << infoLog << std::endl;
	}

	unsigned int shaderProgram;
	shaderProgram = glCreateProgram();//创建着色器程序对象
	glAttachShader(shaderProgram, vertexShader);//附加顶点着色器
	glAttachShader(shaderProgram, fragmentShader);//附件片段着色器
	glLinkProgram(shaderProgram);//连接着色器程序

	glGetProgramiv(shaderProgram, GL_LINK_STATUS, &success);//判断链接是否成功
	if (!success)
	{
		glGetProgramInfoLog(shaderProgram, 512, NULL, infoLog);
		std::cout << "ERROR::SHADER::PROGRAM::COMPILATION_FAILED\n" << infoLog << std::endl;
	}

	glDeleteShader(vertexShader);//创建完成 删除不需要的缓存
	glDeleteShader(fragmentShader);

	while (!glfwWindowShouldClose(window))//渲染循环，检查GLFW是否被要求退出。
	{
		glClearColor(0.2f, 0.3f, 0.3f, 1.0f);//清理屏幕
		glClear(GL_COLOR_BUFFER_BIT);

		glUseProgram(shaderProgram);//激活着色器程序
		glBindVertexArray(VAO);//绑定VAO
		glDrawArrays(GL_TRIANGLES, 0, 3);//绘制模型

		glfwSwapBuffers(window);//交换颜色缓存
		glfwPollEvents();//检测触发事件
	}

	glfwTerminate();//释放所有资源
	return 0;
}

void framebuffer_size_callback(GLFWwindow* window, int width, int height)
{
	glViewport(0, 0, width, height);
}

 

结果：

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本文是根据LearnOpenGL教程自己整理的笔记，详细的教程内容请到LearnOpenGL官网查看。地址：https://learnopengl-cn.github.io/