计算机图形学-实验

实验

GLFW

GLAD

//渲染
while (!glfwWindowShouldClose(window))

{

	//glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
	glClearColor(0.0f, 0.34f, 0.57f, 1.0f);
	glClear(GL_COLOR_BUFFER_BIT);

	//交换颜色缓存，开始绘制
	glfwSwapBuffers(window);
	//检查触发事件
	glfwPollEvents();

}

VAO 顶点数组对象

VBO 顶点缓冲对象

实验一：绘制三角形

#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <iostream>

using namespace std;

const unsigned int SCR_WIDTH = 800;
const unsigned int SCR_HEIGHT = 600;

int main()
{

	//cout << SCR_HEIGHT << endl;

	/*
	
	初始化OpenGL
	  1)初始化GLFW 
	  2)创建窗口
	  3)初始化GLAD
	  4)创建视口
	
	*/

	// 1）初始化GLFW
	glfwInit();
	//设置主版本号、次版本号为3.3
	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
	//使用核心模式，即只能使用openGL功能的一个子集（没有向后兼容特性）
	glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
	//Mac OS需要加上这句   glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
	//不可改变窗口大小
	glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);

	
	// 2)设置GLFW窗口对象
	GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL);

	if (window == NULL)

	{
		//若未创建成功，终止程序
		std::cout << "Failed to create GLFW window" << std::endl;

		glfwTerminate();

		return -1;

	}

	//设置GLFW上下文(状态)为当前线程的上下文
	glfwMakeContextCurrent(window);

	//GLAD管理OpenGL函数指针
	if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
	{

		std::cout << "Failed to initialize GLAD" << std::endl;
		return -1;

	}

	//指定当前视口尺寸（左下角坐标，视口宽高）
	glViewport(0, 0, SCR_WIDTH, SCR_HEIGHT);


	/*
	    数据处理
	*/
	  //1）三角形三个顶点输入（标准化，0-1之间）
	const float triangle[] = {
		  -0.5f,-0.5f,0.0f, //左下
		   0.5f,-0.5f,0.0f, //右下
			0.0f,0.5f,0.0f  //正上
	};

	  //2）VAO（顶点数组对象） VBO（顶点缓冲对象）
	GLuint vertex_array_object;
	glGenVertexArrays(1, &vertex_array_object);
	glBindVertexArray(vertex_array_object);

	GLuint vertex_buffer_object;
	glGenBuffers(1, &vertex_buffer_object);
	glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer_object);
	glBufferData(GL_ARRAY_BUFFER, sizeof(triangle), triangle, GL_STATIC_DRAW);

	//设置顶点属性指针
    //顶点着色器的位置，顶点属性为3分量向量，是否标准化，连续顶点属性之间的间隔，数据偏移量
	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
	glEnableVertexAttribArray(0);
	
	// 3) 生成并编译着色器
	const char *vertex_shader_source =
		"#version 330 core\n"
		"layout(location = 0 ) in vec3 aPos;\n"   
		"void main()\n"
		"{\n"
		" gl_Position = vec4(aPos, 1.0);\n"
		"}\n\0";

	const char *fragment_shader_source =
		"#version 330 core\n"
		"out vec4 FragColor;\n"
		"void main()\n"
		"{\n"
		" FragColor = vec4(1.0f, 0.5f, 0.2f, 1.0f);\n"
		"}\n\0"	;

	//状态标识量
	int success;
	char info_log[512];
	
	//顶点着色器
	int vertex_shader = glCreateShader(GL_VERTEX_SHADER);
	glShaderSource(vertex_shader, 1, &vertex_shader_source, NULL);
	glCompileShader(vertex_shader);
	//检查编译是否成功
	glGetShaderiv(vertex_shader, GL_COMPILE_STATUS, &success);
	if (!success) {

		glGetShaderInfoLog(vertex_shader, 512, NULL, info_log);
		cout<<"error 1:"<< info_log << endl;
	}
	//片段着色器
	int fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
	glShaderSource(fragment_shader, 1, &fragment_shader_source, NULL);
	glCompileShader(fragment_shader);
	//检查编译是否成功
	glGetShaderiv(fragment_shader, GL_COMPILE_STATUS, &success);
	if (!success) {

		glGetShaderInfoLog(fragment_shader, 512, NULL, info_log);
		cout << "error 2:" << info_log << endl;
	}
	//链接顶点和片段着色器至一个着色器程序
	int shader_program = glCreateProgram();
	glAttachShader(shader_program, vertex_shader);
	glAttachShader(shader_program, fragment_shader);
	glLinkProgram(shader_program);
	//检查链接是否成功
	glGetProgramiv(shader_program, GL_LINK_STATUS, &success);
	if (!success) {

		glGetProgramInfoLog(fragment_shader, 512, NULL, info_log);
		cout << "error 3:" << info_log << endl;
	}


	//渲染
	while (!glfwWindowShouldClose(window))

	{
		//渲染指令
		glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
		//清空颜色缓冲后，填充蓝色
		//glClearColor(0.0f, 0.34f, 0.57f, 1.0f);
		//清除颜色缓冲
		glClear(GL_COLOR_BUFFER_BIT);
        
		//使用着色器程序
		glUseProgram(shader_program);
		//绘制三角形
		glBindVertexArray(vertex_array_object);
		glDrawArrays(GL_TRIANGLES, 0, 3);
		//解除绑定
		glBindVertexArray(0);

		//交换颜色缓存，开始绘制
		glfwSwapBuffers(window);
		//检查触发事件
		glfwPollEvents();

	}

	//删除VAO VBO
	glDeleteVertexArrays(1,&vertex_array_object);
	glDeleteBuffers(1, &vertex_buffer_object);

	//释放资源
	glfwTerminate();

	return 0;

}