C++ OpenGL實(shí)現(xiàn)三角形的繪制

更新時(shí)間：2022年06月24日 14:32:26 作者：代碼騎士

這篇文章主要主要為大家詳細(xì)介紹了如何利用C++和OpenGL實(shí)現(xiàn)三角形的繪制，文中的示例代碼講解詳細(xì)，感興趣的小伙伴可以跟隨小編一起動(dòng)手嘗試一下

一、繪制三角形

1、初始化

（1）初始化GLFW

//初始化GLFW
    glfwInit();//初始化GLFW
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);//設(shè)置主版本號(hào)
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);//設(shè)置次版本號(hào)
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);//設(shè)置核心模式
    //glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);//MAC OS
    glfwWindowHint(GLFW_RESIZABLE, false);//關(guān)閉可調(diào)節(jié)窗口大小

（2）創(chuàng)建一個(gè)窗口

//創(chuàng)建窗口(寬、高、窗口名)
    auto window = glfwCreateWindow(screen_width, screen_hight, "Triangle", nullptr, nullptr);
    if (window == nullptr) {
        std::cout << "Failed to Create OpenGL Context" << std::endl;
        glfwTerminate();
        return -1;
    }
    glfwMakeContextCurrent(window);

（3）初始化GLAD

//初始化GLAD
    if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
    {
        std::cout << "Failed to initialize GLAD" << std::endl;
        return -1;
    }

（4）創(chuàng)建一個(gè)視口

//創(chuàng)建視口
    glViewport(0, 0, screen_width, screen_hight);

初始化代碼（全）：

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

#include <iostream>

const int screen_width = 800;
const int screen_hight = 600;

int main() {

	//初始化GLFW
	glfwInit();//初始化GLFW
	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);//設(shè)置主版本號(hào)
	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);//設(shè)置次版本號(hào)
	glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);//設(shè)置核心模式
	//glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);//MAC OS
	glfwWindowHint(GLFW_RESIZABLE, false);//關(guān)閉可調(diào)節(jié)窗口大小
	
	//創(chuàng)建窗口(寬、高、窗口名)
	auto window = glfwCreateWindow(screen_width, screen_hight, "Triangle", nullptr, nullptr);
	if (window == nullptr) {
		std::cout << "Failed to Create OpenGL Context" << std::endl;
		glfwTerminate();
		return -1;
	}
	glfwMakeContextCurrent(window);

	//初始化GLAD
	if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
	{
		std::cout << "Failed to initialize GLAD" << std::endl;
		return -1;
	}

	//創(chuàng)建視口
	glViewport(0, 0, screen_width, screen_hight);

	return 0;
}

2、頂點(diǎn)輸入

坐標(biāo)系規(guī)定

頂點(diǎn)坐標(biāo)代碼

//三角形的頂點(diǎn)數(shù)據(jù)
const float triangle[] = {
    //--位置--//
    -0.5f,-0.5f,0.0f,//左下
    0.5f,-0.5f,0.0f,//右下
    0.0f,0.5f,0.0f,//正上
};

3、數(shù)據(jù)處理

（1）VBO、VAO

//生成并綁定VBO
    GLuint vertex_buffer_object;
    glGenBuffers(1, &vertex_buffer_object);
    glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer_object);
    //將頂點(diǎn)數(shù)據(jù)綁定至默認(rèn)的緩沖中
    glBufferData(GL_ARRAY_BUFFER, sizeof(triangle), triangle, GL_STATIC_DRAW);

//生成并綁定VAO
    GLuint vertex_array_object;
    glGenVertexArrays(1, &vertex_array_object);
    glBindVertexArray(vertex_array_object);

（2）頂點(diǎn)屬性

//設(shè)置頂點(diǎn)屬性指針
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float),(void*)0);
    glEnableVertexAttribArray(0);

（3）解綁代碼

//設(shè)置完成之后就可以解綁VBO、VAO了
    glBindVertexArray(0);
    glBindBuffer(GL_ARRAY_BUFFER, 0);

4、頂點(diǎn)著色器和片段著色器

//頂點(diǎn)著色器源碼
    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";

//片段著色器源碼
    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";

//生成并編譯著色器
    //頂點(diǎn)著色器
    int vertex_shader = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertex_shader, 1, &vertex_shader_source, NULL);
    glCompileShader(vertex_shader);
    int success;
    char info_log[512];
    // 檢查著色器是否成功編譯，如果編譯失敗，打印錯(cuò)誤信息
    glGetShaderiv(vertex_shader, GL_COMPILE_STATUS, &success);
    if (!success)
    {
        glGetShaderInfoLog(vertex_shader, 512, NULL, info_log);
        std::cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << info_log << std::endl;
    }
    // 片段著色器
    int fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fragment_shader, 1, &fragment_shader_source, NULL);
    glCompileShader(fragment_shader);
    // 檢查著色器是否成功編譯，如果編譯失敗，打印錯(cuò)誤信息
    glGetShaderiv(fragment_shader, GL_COMPILE_STATUS, &success);
    if (!success)
    {
        glGetShaderInfoLog(fragment_shader, 512, NULL, info_log);
        std::cout << "ERROR::SHADER::FRAGMENT::COMPILATION_FAILED\n" << info_log << std::endl;
    }

// 鏈接頂點(diǎn)和片段著色器至一個(gè)著色器程序
    int shader_program = glCreateProgram();
    glAttachShader(shader_program, vertex_shader);
    glAttachShader(shader_program, fragment_shader);
    glLinkProgram(shader_program);
    // 檢查著色器是否成功鏈接，如果鏈接失敗，打印錯(cuò)誤信息
    glGetProgramiv(shader_program, GL_LINK_STATUS, &success);
    if (!success) {
        glGetProgramInfoLog(shader_program, 512, NULL, info_log);
        std::cout << "ERROR::SHADER::PROGRAM::LINKING_FAILED\n" << info_log << std::endl;
    }
    // 刪除著色器
    glDeleteShader(vertex_shader);
    glDeleteShader(fragment_shader);

// 線框模式
    //glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);

5、渲染

//渲染循環(huán)
	while (!glfwWindowShouldClose(window)) {

		// 清空顏色緩沖
		glClearColor(0.0f, 0.34f, 0.57f, 1.0f);
		glClear(GL_COLOR_BUFFER_BIT);

		// 使用著色器程序
		glUseProgram(shader_program);

		// 繪制三角形
		glBindVertexArray(vertex_array_object);                                    // 綁定VAO
		glDrawArrays(GL_TRIANGLES, 0, 3);                                          // 繪制三角形
		glBindVertexArray(0);                                                      // 解除綁定

		// 交換緩沖并且檢查是否有觸發(fā)事件(比如鍵盤(pán)輸入、鼠標(biāo)移動(dòng)等）
		glfwSwapBuffers(window);
		glfwPollEvents();
	}

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

二、完整代碼

代碼

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

#include <iostream>

const int screen_width = 800;
const int screen_hight = 600;

//三角形的頂點(diǎn)數(shù)據(jù)
const float triangle[] = {
	//--位置--//
	-0.5f,-0.5f,0.0f,//左下
	0.5f,-0.5f,0.0f,//右下
	0.0f,0.5f,0.0f,//正上
};

int main() {

	//初始化GLFW
	glfwInit();//初始化GLFW
	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);//設(shè)置主版本號(hào)
	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);//設(shè)置次版本號(hào)
	glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);//設(shè)置核心模式
	//glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);//MAC OS
	glfwWindowHint(GLFW_RESIZABLE, false);//關(guān)閉可調(diào)節(jié)窗口大小

	//創(chuàng)建窗口(寬、高、窗口名)
	auto window = glfwCreateWindow(screen_width, screen_hight, "Triangle", nullptr, nullptr);
	if (window == nullptr) {
		std::cout << "Failed to Create OpenGL Context" << std::endl;
		glfwTerminate();
		return -1;
	}
	glfwMakeContextCurrent(window);

	//初始化GLAD
	if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
	{
		std::cout << "Failed to initialize GLAD" << std::endl;
		return -1;
	}

	//創(chuàng)建視口
	glViewport(0, 0, screen_width, screen_hight);

	//生成并綁定VBO
	GLuint vertex_buffer_object;
	glGenBuffers(1, &vertex_buffer_object);
	glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer_object);
	//將頂點(diǎn)數(shù)據(jù)綁定至默認(rèn)的緩沖中
	glBufferData(GL_ARRAY_BUFFER, sizeof(triangle), triangle, GL_STATIC_DRAW);
	//生成并綁定VAO
	GLuint vertex_array_object;
	glGenVertexArrays(1, &vertex_array_object);
	glBindVertexArray(vertex_array_object);

	//設(shè)置頂點(diǎn)屬性指針
	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);//參數(shù)：頂點(diǎn)著色器位置值，分量，頂點(diǎn)數(shù)據(jù)類(lèi)型，是否標(biāo)準(zhǔn)化，步長(zhǎng)、數(shù)據(jù)偏移量
	glEnableVertexAttribArray(0);//開(kāi)啟0通道

	//設(shè)置完成之后就可以解綁VBO、VAO了
	glBindVertexArray(0);
	glBindBuffer(GL_ARRAY_BUFFER, 0);

	//頂點(diǎn)著色器源碼
	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";

	//片段著色器源碼
	const char* fragment_shader_source =
		"#version 330 core\n"
		"out vec4 FragColor;\n"
		"void main()\n"
		"{\n"
		"	FragColor = vec4(1.0f,0.1f,0.1f,1.0f);\n"
		"}\n\0";

	//生成并編譯著色器
	//頂點(diǎn)著色器
	int vertex_shader = glCreateShader(GL_VERTEX_SHADER);
	glShaderSource(vertex_shader, 1, &vertex_shader_source, NULL);
	glCompileShader(vertex_shader);
	int success;
	char info_log[512];
	// 檢查著色器是否成功編譯，如果編譯失敗，打印錯(cuò)誤信息
	glGetShaderiv(vertex_shader, GL_COMPILE_STATUS, &success);
	if (!success)
	{
		glGetShaderInfoLog(vertex_shader, 512, NULL, info_log);
		std::cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << info_log << std::endl;
	}
	// 片段著色器
	int fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
	glShaderSource(fragment_shader, 1, &fragment_shader_source, NULL);
	glCompileShader(fragment_shader);
	// 檢查著色器是否成功編譯，如果編譯失敗，打印錯(cuò)誤信息
	glGetShaderiv(fragment_shader, GL_COMPILE_STATUS, &success);
	if (!success)
	{
		glGetShaderInfoLog(fragment_shader, 512, NULL, info_log);
		std::cout << "ERROR::SHADER::FRAGMENT::COMPILATION_FAILED\n" << info_log << std::endl;
	}
	// 鏈接頂點(diǎn)和片段著色器至一個(gè)著色器程序
	int shader_program = glCreateProgram();
	glAttachShader(shader_program, vertex_shader);
	glAttachShader(shader_program, fragment_shader);
	glLinkProgram(shader_program);
	// 檢查著色器是否成功鏈接，如果鏈接失敗，打印錯(cuò)誤信息
	glGetProgramiv(shader_program, GL_LINK_STATUS, &success);
	if (!success) {
		glGetProgramInfoLog(shader_program, 512, NULL, info_log);
		std::cout << "ERROR::SHADER::PROGRAM::LINKING_FAILED\n" << info_log << std::endl;
	}
	// 刪除著色器
	glDeleteShader(vertex_shader);
	glDeleteShader(fragment_shader);

	// 線框模式
	//glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);

	//渲染循環(huán)
	while (!glfwWindowShouldClose(window)) {

		// 清空顏色緩沖
		glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
		glClear(GL_COLOR_BUFFER_BIT);

		// 使用著色器程序
		glUseProgram(shader_program);

		// 繪制三角形
		glBindVertexArray(vertex_array_object);                                    // 綁定VAO
		glDrawArrays(GL_TRIANGLES, 0, 3);                                          // 繪制三角形
		glBindVertexArray(0);                                                      // 解除綁定

		// 交換緩沖并且檢查是否有觸發(fā)事件(比如鍵盤(pán)輸入、鼠標(biāo)移動(dòng)等）
		glfwSwapBuffers(window);
		glfwPollEvents();
	}

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

	// 清理所有的資源并正確退出程序
	glfwTerminate();
	return 0;
}