OpenGL笔记七之顶点数据绘制命令和绘制模式

笑鸿的学习笔记2024-07-10 19:08

OpenGL笔记七之顶点数据绘制命令和绘制模式

------ 2024-07-07 杭州 下午

总结自bilibili赵新政老师的教程

code review!

文章目录

1.OpenGL版本号更改和编译更改

"#version 330 core\n"

glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);

2.GL_TRIANGLES模式绘制一个三角形、支持NFC坐标随窗口缩放

2.1.三个点

运行

关键代码

cpp 复制代码 
prepareInterleavedBuffer();
// prepareVAOForGLTriangles();
cpp 复制代码 
glDrawArrays(GL_TRIANGLES, 0, 3);
// glDrawArrays(GL_LINE_STRIP, 0, 6);

main.cpp

cpp 复制代码 
#include <iostream>

#define DEBUG

//注意：glad头文件必须在glfw引用之前引用
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <string>
#include <assert.h>//断言
#include "wrapper/checkError.h"
#include "application/Application.h"

/*
*┌────────────────────────────────────────────────┐
*│　目	   标： 学习glDrawArrays进行绘制命令
*│　讲    师： 赵新政(Carma Zhao)
*│　拆分目标：
*│
*│　		1  采用GL_TRANGLES进行绘制
*				** 这里大家可以缩放窗体，实验NDC坐标的作用

*│　		2  prepareVAOForGLTriangles:构建四个顶点的vao
*│　		3  测试Triangle的三种mode：TRIANGLES  TRIANGLE_STRIP TRIANGLE_FAN
*│　		4  测试Line的二种mode：LINES  LINE_STRIP
*└────────────────────────────────────────────────┘
*/

GLuint vao, program;


void OnResize(int width, int height) {
	GL_CALL(glViewport(0, 0, width, height));
	std::cout << "OnResize" << std::endl;
}

void OnKey(int key, int action, int mods) {
	std::cout << key << std::endl;
}

void prepareSingleBuffer() {
	//1 准备positions colors数据
	float positions[] = {
		   -0.5f, -0.5f, 0.0f,
			0.5f, -0.5f, 0.0f,
			0.0f,  0.5f, 0.0f
	};
	float colors[] = {
	   1.0f, 0.0f, 0.0f,
	   0.0f, 1.0f, 0.0f,
	   0.0f,  0.0f, 1.0f
	};


	//2 使用数据生成两个vbo posVbo， colorVbo
	GLuint posVbo, colorVbo;
	glGenBuffers(1, &posVbo);
	glGenBuffers(1, &colorVbo);

	glBindBuffer(GL_ARRAY_BUFFER, posVbo);
	glBufferData(GL_ARRAY_BUFFER, sizeof(positions), positions, GL_STATIC_DRAW);

	glBindBuffer(GL_ARRAY_BUFFER, colorVbo);
	glBufferData(GL_ARRAY_BUFFER, sizeof(colors), colors, GL_STATIC_DRAW);

	//3 生成vao并且绑定
	GLuint vao = 0;
	glGenVertexArrays(1, &vao);
	glBindVertexArray(vao);

	//4 分别将位置/颜色属性的描述信息加入vao当中
	//4.1描述位置属性
	glBindBuffer(GL_ARRAY_BUFFER, posVbo);//只有绑定了posVbo，下面的属性描述才会与此vbo相关
	glEnableVertexAttribArray(0);
	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);

	//4.2 描述颜色属性
	glBindBuffer(GL_ARRAY_BUFFER, colorVbo);
	glEnableVertexAttribArray(1);
	glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);

	glBindVertexArray(0);
}


void prepareInterleavedBuffer() {
	//1 准备好Interleaved数据（位置+颜色）
	float vertices[] = {
		   -0.5f, -0.5f, 0.0f,  1.0f, 0.0f, 0.0f,
			0.5f, -0.5f, 0.0f,  0.0f, 1.0f, 0.0f,
			0.0f,  0.5f, 0.0f,  0.0f,  0.0f, 1.0f
	};


	//2 创建唯一的vbo
	GLuint vbo = 0;
	GL_CALL(glGenBuffers(1, &vbo));
	GL_CALL(glBindBuffer(GL_ARRAY_BUFFER, vbo));
	GL_CALL(glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW));

	//3 创建并绑定vao
	GL_CALL(glGenVertexArrays(1, &vao));
	GL_CALL(glBindVertexArray(vao));


	GL_CALL(glBindBuffer(GL_ARRAY_BUFFER, vbo));
	//4 为vao加入位置和颜色的描述信息
	//4.1 位置描述信息
	GL_CALL(glEnableVertexAttribArray(0));
	GL_CALL(glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0));

	//4.2 颜色描述信息
	GL_CALL(glEnableVertexAttribArray(1));
	GL_CALL(glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)(3 * sizeof(float))));

	//5 扫尾工作：解绑当前vao
	glBindVertexArray(0);
}

void prepareVAOForGLTriangles() {
	//1 准备positions
	float positions[] = {
		-0.5f, -0.5f, 0.0f,
		0.5f, -0.5f, 0.0f,
		0.0f,  0.5f, 0.0f,
		0.5f,  0.5f, 0.0f,
		0.8f,  0.8f, 0.0f,
		0.8f,  0.0f, 0.0f
	};


	//2  posVbo
	GLuint posVbo;
	glGenBuffers(1, &posVbo);

	glBindBuffer(GL_ARRAY_BUFFER, posVbo);
	glBufferData(GL_ARRAY_BUFFER, sizeof(positions), positions, GL_STATIC_DRAW);

	//3 生成vao并且绑定
	glGenVertexArrays(1, &vao);
	glBindVertexArray(vao);

	//4 描述位置属性
	glBindBuffer(GL_ARRAY_BUFFER, posVbo);
	glEnableVertexAttribArray(0);
	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);

	glBindVertexArray(0);
}

void prepareShader() {
	//1 完成vs与fs的源代码，并且装入字符串
	const char* vertexShaderSource =
		"#version 330 core\n"
		"layout (location = 0) in vec3 aPos;\n"
		"void main()\n"
		"{\n"
		"   gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);\n"
		"}\0";
	const char* fragmentShaderSource =
		"#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";


	//2 创建Shader程序（vs、fs）
	GLuint vertex, fragment;
	vertex = glCreateShader(GL_VERTEX_SHADER);
	fragment = glCreateShader(GL_FRAGMENT_SHADER);


	//3 为shader程序输入shader代码
	glShaderSource(vertex, 1, &vertexShaderSource, NULL);
	glShaderSource(fragment, 1, &fragmentShaderSource, NULL);

	int success = 0;
	char infoLog[1024];
	//4 执行shader代码编译 
	glCompileShader(vertex);
	//检查vertex编译结果
	glGetShaderiv(vertex, GL_COMPILE_STATUS, &success);
	if (!success) {
		glGetShaderInfoLog(vertex, 1024, NULL, infoLog);
		std::cout << "Error: SHADER COMPILE ERROR --VERTEX" << "\n" << infoLog << std::endl;
	}

	glCompileShader(fragment);
	//检查fragment编译结果
	glGetShaderiv(fragment, GL_COMPILE_STATUS, &success);
	if (!success) {
		glGetShaderInfoLog(fragment, 1024, NULL, infoLog);
		std::cout << "Error: SHADER COMPILE ERROR --FRAGMENT" << "\n" << infoLog << std::endl;
	}

	//5 创建一个Program壳子
	program = glCreateProgram();

	//6 将vs与fs编译好的结果放到program这个壳子里
	glAttachShader(program, vertex);
	glAttachShader(program, fragment);

	//7 执行program的链接操作，形成最终可执行shader程序
	glLinkProgram(program);

	//检查链接错误
	glGetProgramiv(program, GL_LINK_STATUS, &success);
	if (!success) {
		glGetProgramInfoLog(program, 1024, NULL, infoLog);
		std::cout << "Error: SHADER LINK ERROR " << "\n" << infoLog << std::endl;
	}

	//清理
	glDeleteShader(vertex);
	glDeleteShader(fragment);
}

void render() {
	//执行opengl画布清理操作
	GL_CALL(glClear(GL_COLOR_BUFFER_BIT));

	//1 绑定当前的program
	glUseProgram(program);

	//2 绑定当前的vao
	glBindVertexArray(vao);

	//3 发出绘制指令
	glDrawArrays(GL_TRIANGLES, 0, 3);
	// glDrawArrays(GL_LINE_STRIP, 0, 6);
}


int main() {
	if (!app->init(800, 600)) {
		return -1;
	}

	app->setResizeCallback(OnResize);
	app->setKeyBoardCallback(OnKey);

	//设置opengl视口以及清理颜色
	GL_CALL(glViewport(0, 0, 800, 600));
	GL_CALL(glClearColor(0.2f, 0.3f, 0.3f, 1.0f));
	prepareShader();
	prepareInterleavedBuffer();
	// prepareVAOForGLTriangles();
	while (app->update()) {
		render();
	}
	app->destroy();
	return 0;
}

2.2.四个点从0号点开始数3个点

运行

关键代码

cpp 复制代码 
// prepareInterleavedBuffer();
prepareVAOForGLTriangles();
cpp 复制代码 
float positions[] = {
	-0.5f, -0.5f, 0.0f,
	0.5f, -0.5f, 0.0f,
	0.0f,  0.5f, 0.0f,
	0.5f,  0.5f, 0.0f,
	// 0.8f,  0.8f, 0.0f,
	// 0.8f,  0.0f, 0.0f
};

main.cpp

cpp 复制代码 
#include <iostream>

#define DEBUG

//注意：glad头文件必须在glfw引用之前引用
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <string>
#include <assert.h>//断言
#include "wrapper/checkError.h"
#include "application/Application.h"

/*
*┌────────────────────────────────────────────────┐
*│　目	   标： 学习glDrawArrays进行绘制命令
*│　讲    师： 赵新政(Carma Zhao)
*│　拆分目标：
*│
*│　		1  采用GL_TRANGLES进行绘制
*				** 这里大家可以缩放窗体，实验NDC坐标的作用

*│　		2  prepareVAOForGLTriangles:构建四个顶点的vao
*│　		3  测试Triangle的三种mode：TRIANGLES  TRIANGLE_STRIP TRIANGLE_FAN
*│　		4  测试Line的二种mode：LINES  LINE_STRIP
*└────────────────────────────────────────────────┘
*/

GLuint vao, program;


void OnResize(int width, int height) {
	GL_CALL(glViewport(0, 0, width, height));
	std::cout << "OnResize" << std::endl;
}

void OnKey(int key, int action, int mods) {
	std::cout << key << std::endl;
}

void prepareSingleBuffer() {
	//1 准备positions colors数据
	float positions[] = {
		   -0.5f, -0.5f, 0.0f,
			0.5f, -0.5f, 0.0f,
			0.0f,  0.5f, 0.0f
	};
	float colors[] = {
	   1.0f, 0.0f, 0.0f,
	   0.0f, 1.0f, 0.0f,
	   0.0f,  0.0f, 1.0f
	};


	//2 使用数据生成两个vbo posVbo， colorVbo
	GLuint posVbo, colorVbo;
	glGenBuffers(1, &posVbo);
	glGenBuffers(1, &colorVbo);

	glBindBuffer(GL_ARRAY_BUFFER, posVbo);
	glBufferData(GL_ARRAY_BUFFER, sizeof(positions), positions, GL_STATIC_DRAW);

	glBindBuffer(GL_ARRAY_BUFFER, colorVbo);
	glBufferData(GL_ARRAY_BUFFER, sizeof(colors), colors, GL_STATIC_DRAW);

	//3 生成vao并且绑定
	GLuint vao = 0;
	glGenVertexArrays(1, &vao);
	glBindVertexArray(vao);

	//4 分别将位置/颜色属性的描述信息加入vao当中
	//4.1描述位置属性
	glBindBuffer(GL_ARRAY_BUFFER, posVbo);//只有绑定了posVbo，下面的属性描述才会与此vbo相关
	glEnableVertexAttribArray(0);
	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);

	//4.2 描述颜色属性
	glBindBuffer(GL_ARRAY_BUFFER, colorVbo);
	glEnableVertexAttribArray(1);
	glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);

	glBindVertexArray(0);
}


void prepareInterleavedBuffer() {
	//1 准备好Interleaved数据（位置+颜色）
	float vertices[] = {
		   -0.5f, -0.5f, 0.0f,  1.0f, 0.0f, 0.0f,
			0.5f, -0.5f, 0.0f,  0.0f, 1.0f, 0.0f,
			0.0f,  0.5f, 0.0f,  0.0f,  0.0f, 1.0f
	};


	//2 创建唯一的vbo
	GLuint vbo = 0;
	GL_CALL(glGenBuffers(1, &vbo));
	GL_CALL(glBindBuffer(GL_ARRAY_BUFFER, vbo));
	GL_CALL(glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW));

	//3 创建并绑定vao
	GL_CALL(glGenVertexArrays(1, &vao));
	GL_CALL(glBindVertexArray(vao));


	GL_CALL(glBindBuffer(GL_ARRAY_BUFFER, vbo));
	//4 为vao加入位置和颜色的描述信息
	//4.1 位置描述信息
	GL_CALL(glEnableVertexAttribArray(0));
	GL_CALL(glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0));

	//4.2 颜色描述信息
	GL_CALL(glEnableVertexAttribArray(1));
	GL_CALL(glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)(3 * sizeof(float))));

	//5 扫尾工作：解绑当前vao
	glBindVertexArray(0);
}

void prepareVAOForGLTriangles() {
	//1 准备positions
	float positions[] = {
		-0.5f, -0.5f, 0.0f,
		0.5f, -0.5f, 0.0f,
		0.0f,  0.5f, 0.0f,
		0.5f,  0.5f, 0.0f,
		// 0.8f,  0.8f, 0.0f,
		// 0.8f,  0.0f, 0.0f
	};


	//2  posVbo
	GLuint posVbo;
	glGenBuffers(1, &posVbo);

	glBindBuffer(GL_ARRAY_BUFFER, posVbo);
	glBufferData(GL_ARRAY_BUFFER, sizeof(positions), positions, GL_STATIC_DRAW);

	//3 生成vao并且绑定
	glGenVertexArrays(1, &vao);
	glBindVertexArray(vao);

	//4 描述位置属性
	glBindBuffer(GL_ARRAY_BUFFER, posVbo);
	glEnableVertexAttribArray(0);
	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);

	glBindVertexArray(0);
}

void prepareShader() {
	//1 完成vs与fs的源代码，并且装入字符串
	const char* vertexShaderSource =
		"#version 330 core\n"
		"layout (location = 0) in vec3 aPos;\n"
		"void main()\n"
		"{\n"
		"   gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);\n"
		"}\0";
	const char* fragmentShaderSource =
		"#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";


	//2 创建Shader程序（vs、fs）
	GLuint vertex, fragment;
	vertex = glCreateShader(GL_VERTEX_SHADER);
	fragment = glCreateShader(GL_FRAGMENT_SHADER);


	//3 为shader程序输入shader代码
	glShaderSource(vertex, 1, &vertexShaderSource, NULL);
	glShaderSource(fragment, 1, &fragmentShaderSource, NULL);

	int success = 0;
	char infoLog[1024];
	//4 执行shader代码编译 
	glCompileShader(vertex);
	//检查vertex编译结果
	glGetShaderiv(vertex, GL_COMPILE_STATUS, &success);
	if (!success) {
		glGetShaderInfoLog(vertex, 1024, NULL, infoLog);
		std::cout << "Error: SHADER COMPILE ERROR --VERTEX" << "\n" << infoLog << std::endl;
	}

	glCompileShader(fragment);
	//检查fragment编译结果
	glGetShaderiv(fragment, GL_COMPILE_STATUS, &success);
	if (!success) {
		glGetShaderInfoLog(fragment, 1024, NULL, infoLog);
		std::cout << "Error: SHADER COMPILE ERROR --FRAGMENT" << "\n" << infoLog << std::endl;
	}

	//5 创建一个Program壳子
	program = glCreateProgram();

	//6 将vs与fs编译好的结果放到program这个壳子里
	glAttachShader(program, vertex);
	glAttachShader(program, fragment);

	//7 执行program的链接操作，形成最终可执行shader程序
	glLinkProgram(program);

	//检查链接错误
	glGetProgramiv(program, GL_LINK_STATUS, &success);
	if (!success) {
		glGetProgramInfoLog(program, 1024, NULL, infoLog);
		std::cout << "Error: SHADER LINK ERROR " << "\n" << infoLog << std::endl;
	}

	//清理
	glDeleteShader(vertex);
	glDeleteShader(fragment);
}

void render() {
	//执行opengl画布清理操作
	GL_CALL(glClear(GL_COLOR_BUFFER_BIT));

	//1 绑定当前的program
	glUseProgram(program);

	//2 绑定当前的vao
	glBindVertexArray(vao);

	//3 发出绘制指令
	glDrawArrays(GL_TRIANGLES, 0, 3);
	// glDrawArrays(GL_LINE_STRIP, 0, 6);
}


int main() {
	if (!app->init(800, 600)) {
		return -1;
	}

	app->setResizeCallback(OnResize);
	app->setKeyBoardCallback(OnKey);

	//设置opengl视口以及清理颜色
	GL_CALL(glViewport(0, 0, 800, 600));
	GL_CALL(glClearColor(0.2f, 0.3f, 0.3f, 1.0f));
	prepareShader();
	// prepareInterleavedBuffer();
	prepareVAOForGLTriangles();
	while (app->update()) {
		render();
	}
	app->destroy();
	return 0;
}

2.3.四个点从1号点开始数3个点

运行

关键代码

cpp 复制代码 
glDrawArrays(GL_TRIANGLES, 1, 3);

2.4.四个点从2号点开始数3个点

运行

关键代码

cpp 复制代码 
glDrawArrays(GL_TRIANGLES, 2, 3);

2.5.六个点从0号点开始数6个点

运行

关键代码

cpp 复制代码 
glDrawArrays(GL_TRIANGLES, 0, 6);
cpp 复制代码 
float positions[] = {
	-0.5f, -0.5f, 0.0f,
	0.5f, -0.5f, 0.0f,
	0.0f,  0.5f, 0.0f,
	0.5f,  0.5f, 0.0f,
	0.8f,  0.8f, 0.0f,
	0.8f,  0.0f, 0.0f
};

2.6.六个点从0号点开始数5个点

运行

关键代码

cpp 复制代码 
glDrawArrays(GL_TRIANGLES, 0, 5);

3.GL_TRIANGLE_STRIP模式绘制三角形

运行

关键代码

cpp 复制代码 
glDrawArrays(GL_TRIANGLE_STRIP, 0, 6);

main.cpp

cpp 复制代码 
#include <iostream>

#define DEBUG

//注意：glad头文件必须在glfw引用之前引用
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <string>
#include <assert.h>//断言
#include "wrapper/checkError.h"
#include "application/Application.h"

/*
*┌────────────────────────────────────────────────┐
*│　目	   标： 学习glDrawArrays进行绘制命令
*│　讲    师： 赵新政(Carma Zhao)
*│　拆分目标：
*│
*│　		1  采用GL_TRANGLES进行绘制
*				** 这里大家可以缩放窗体，实验NDC坐标的作用

*│　		2  prepareVAOForGLTriangles:构建四个顶点的vao
*│　		3  测试Triangle的三种mode：TRIANGLES  TRIANGLE_STRIP TRIANGLE_FAN
*│　		4  测试Line的二种mode：LINES  LINE_STRIP
*└────────────────────────────────────────────────┘
*/

GLuint vao, program;


void OnResize(int width, int height) {
	GL_CALL(glViewport(0, 0, width, height));
	std::cout << "OnResize" << std::endl;
}

void OnKey(int key, int action, int mods) {
	std::cout << key << std::endl;
}

void prepareSingleBuffer() {
	//1 准备positions colors数据
	float positions[] = {
		   -0.5f, -0.5f, 0.0f,
			0.5f, -0.5f, 0.0f,
			0.0f,  0.5f, 0.0f
	};
	float colors[] = {
	   1.0f, 0.0f, 0.0f,
	   0.0f, 1.0f, 0.0f,
	   0.0f,  0.0f, 1.0f
	};


	//2 使用数据生成两个vbo posVbo， colorVbo
	GLuint posVbo, colorVbo;
	glGenBuffers(1, &posVbo);
	glGenBuffers(1, &colorVbo);

	glBindBuffer(GL_ARRAY_BUFFER, posVbo);
	glBufferData(GL_ARRAY_BUFFER, sizeof(positions), positions, GL_STATIC_DRAW);

	glBindBuffer(GL_ARRAY_BUFFER, colorVbo);
	glBufferData(GL_ARRAY_BUFFER, sizeof(colors), colors, GL_STATIC_DRAW);

	//3 生成vao并且绑定
	GLuint vao = 0;
	glGenVertexArrays(1, &vao);
	glBindVertexArray(vao);

	//4 分别将位置/颜色属性的描述信息加入vao当中
	//4.1描述位置属性
	glBindBuffer(GL_ARRAY_BUFFER, posVbo);//只有绑定了posVbo，下面的属性描述才会与此vbo相关
	glEnableVertexAttribArray(0);
	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);

	//4.2 描述颜色属性
	glBindBuffer(GL_ARRAY_BUFFER, colorVbo);
	glEnableVertexAttribArray(1);
	glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);

	glBindVertexArray(0);
}


void prepareInterleavedBuffer() {
	//1 准备好Interleaved数据（位置+颜色）
	float vertices[] = {
		   -0.5f, -0.5f, 0.0f,  1.0f, 0.0f, 0.0f,
			0.5f, -0.5f, 0.0f,  0.0f, 1.0f, 0.0f,
			0.0f,  0.5f, 0.0f,  0.0f,  0.0f, 1.0f
	};


	//2 创建唯一的vbo
	GLuint vbo = 0;
	GL_CALL(glGenBuffers(1, &vbo));
	GL_CALL(glBindBuffer(GL_ARRAY_BUFFER, vbo));
	GL_CALL(glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW));

	//3 创建并绑定vao
	GL_CALL(glGenVertexArrays(1, &vao));
	GL_CALL(glBindVertexArray(vao));


	GL_CALL(glBindBuffer(GL_ARRAY_BUFFER, vbo));
	//4 为vao加入位置和颜色的描述信息
	//4.1 位置描述信息
	GL_CALL(glEnableVertexAttribArray(0));
	GL_CALL(glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0));

	//4.2 颜色描述信息
	GL_CALL(glEnableVertexAttribArray(1));
	GL_CALL(glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)(3 * sizeof(float))));

	//5 扫尾工作：解绑当前vao
	glBindVertexArray(0);
}

void prepareVAOForGLTriangles() {
	//1 准备positions
	float positions[] = {
		-0.5f, -0.5f, 0.0f,
		0.5f, -0.5f, 0.0f,
		0.0f,  0.5f, 0.0f,
		0.5f,  0.5f, 0.0f,
		0.8f,  0.8f, 0.0f,
		0.8f,  0.0f, 0.0f
	};


	//2  posVbo
	GLuint posVbo;
	glGenBuffers(1, &posVbo);

	glBindBuffer(GL_ARRAY_BUFFER, posVbo);
	glBufferData(GL_ARRAY_BUFFER, sizeof(positions), positions, GL_STATIC_DRAW);

	//3 生成vao并且绑定
	glGenVertexArrays(1, &vao);
	glBindVertexArray(vao);

	//4 描述位置属性
	glBindBuffer(GL_ARRAY_BUFFER, posVbo);
	glEnableVertexAttribArray(0);
	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);

	glBindVertexArray(0);
}

void prepareShader() {
	//1 完成vs与fs的源代码，并且装入字符串
	const char* vertexShaderSource =
		"#version 330 core\n"
		"layout (location = 0) in vec3 aPos;\n"
		"void main()\n"
		"{\n"
		"   gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);\n"
		"}\0";
	const char* fragmentShaderSource =
		"#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";


	//2 创建Shader程序（vs、fs）
	GLuint vertex, fragment;
	vertex = glCreateShader(GL_VERTEX_SHADER);
	fragment = glCreateShader(GL_FRAGMENT_SHADER);


	//3 为shader程序输入shader代码
	glShaderSource(vertex, 1, &vertexShaderSource, NULL);
	glShaderSource(fragment, 1, &fragmentShaderSource, NULL);

	int success = 0;
	char infoLog[1024];
	//4 执行shader代码编译 
	glCompileShader(vertex);
	//检查vertex编译结果
	glGetShaderiv(vertex, GL_COMPILE_STATUS, &success);
	if (!success) {
		glGetShaderInfoLog(vertex, 1024, NULL, infoLog);
		std::cout << "Error: SHADER COMPILE ERROR --VERTEX" << "\n" << infoLog << std::endl;
	}

	glCompileShader(fragment);
	//检查fragment编译结果
	glGetShaderiv(fragment, GL_COMPILE_STATUS, &success);
	if (!success) {
		glGetShaderInfoLog(fragment, 1024, NULL, infoLog);
		std::cout << "Error: SHADER COMPILE ERROR --FRAGMENT" << "\n" << infoLog << std::endl;
	}

	//5 创建一个Program壳子
	program = glCreateProgram();

	//6 将vs与fs编译好的结果放到program这个壳子里
	glAttachShader(program, vertex);
	glAttachShader(program, fragment);

	//7 执行program的链接操作，形成最终可执行shader程序
	glLinkProgram(program);

	//检查链接错误
	glGetProgramiv(program, GL_LINK_STATUS, &success);
	if (!success) {
		glGetProgramInfoLog(program, 1024, NULL, infoLog);
		std::cout << "Error: SHADER LINK ERROR " << "\n" << infoLog << std::endl;
	}

	//清理
	glDeleteShader(vertex);
	glDeleteShader(fragment);
}

void render() {
	//执行opengl画布清理操作
	GL_CALL(glClear(GL_COLOR_BUFFER_BIT));

	//1 绑定当前的program
	glUseProgram(program);

	//2 绑定当前的vao
	glBindVertexArray(vao);

	//3 发出绘制指令
	glDrawArrays(GL_TRIANGLE_STRIP, 0, 6);
	// glDrawArrays(GL_TRIANGLES, 0, 6);
	// glDrawArrays(GL_LINE_STRIP, 0, 6);
}


int main() {
	if (!app->init(800, 600)) {
		return -1;
	}

	app->setResizeCallback(OnResize);
	app->setKeyBoardCallback(OnKey);

	//设置opengl视口以及清理颜色
	GL_CALL(glViewport(0, 0, 800, 600));
	GL_CALL(glClearColor(0.2f, 0.3f, 0.3f, 1.0f));
	prepareShader();
	// prepareInterleavedBuffer();
	prepareVAOForGLTriangles();
	while (app->update()) {
		render();
	}
	app->destroy();
	return 0;
}

4.GL_TRIANGLES_FAN模式绘制三角形

运行

关键代码

cpp 复制代码 
glDrawArrays(GL_TRIANGLE_FAN, 0, 6);

main.cpp

cpp 复制代码 
#include <iostream>

#define DEBUG

//注意：glad头文件必须在glfw引用之前引用
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <string>
#include <assert.h>//断言
#include "wrapper/checkError.h"
#include "application/Application.h"

/*
*┌────────────────────────────────────────────────┐
*│　目	   标： 学习glDrawArrays进行绘制命令
*│　讲    师： 赵新政(Carma Zhao)
*│　拆分目标：
*│
*│　		1  采用GL_TRANGLES进行绘制
*				** 这里大家可以缩放窗体，实验NDC坐标的作用

*│　		2  prepareVAOForGLTriangles:构建四个顶点的vao
*│　		3  测试Triangle的三种mode：TRIANGLES  TRIANGLE_STRIP TRIANGLE_FAN
*│　		4  测试Line的二种mode：LINES  LINE_STRIP
*└────────────────────────────────────────────────┘
*/

GLuint vao, program;


void OnResize(int width, int height) {
	GL_CALL(glViewport(0, 0, width, height));
	std::cout << "OnResize" << std::endl;
}

void OnKey(int key, int action, int mods) {
	std::cout << key << std::endl;
}

void prepareSingleBuffer() {
	//1 准备positions colors数据
	float positions[] = {
		   -0.5f, -0.5f, 0.0f,
			0.5f, -0.5f, 0.0f,
			0.0f,  0.5f, 0.0f
	};
	float colors[] = {
	   1.0f, 0.0f, 0.0f,
	   0.0f, 1.0f, 0.0f,
	   0.0f,  0.0f, 1.0f
	};


	//2 使用数据生成两个vbo posVbo， colorVbo
	GLuint posVbo, colorVbo;
	glGenBuffers(1, &posVbo);
	glGenBuffers(1, &colorVbo);

	glBindBuffer(GL_ARRAY_BUFFER, posVbo);
	glBufferData(GL_ARRAY_BUFFER, sizeof(positions), positions, GL_STATIC_DRAW);

	glBindBuffer(GL_ARRAY_BUFFER, colorVbo);
	glBufferData(GL_ARRAY_BUFFER, sizeof(colors), colors, GL_STATIC_DRAW);

	//3 生成vao并且绑定
	GLuint vao = 0;
	glGenVertexArrays(1, &vao);
	glBindVertexArray(vao);

	//4 分别将位置/颜色属性的描述信息加入vao当中
	//4.1描述位置属性
	glBindBuffer(GL_ARRAY_BUFFER, posVbo);//只有绑定了posVbo，下面的属性描述才会与此vbo相关
	glEnableVertexAttribArray(0);
	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);

	//4.2 描述颜色属性
	glBindBuffer(GL_ARRAY_BUFFER, colorVbo);
	glEnableVertexAttribArray(1);
	glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);

	glBindVertexArray(0);
}


void prepareInterleavedBuffer() {
	//1 准备好Interleaved数据（位置+颜色）
	float vertices[] = {
		   -0.5f, -0.5f, 0.0f,  1.0f, 0.0f, 0.0f,
			0.5f, -0.5f, 0.0f,  0.0f, 1.0f, 0.0f,
			0.0f,  0.5f, 0.0f,  0.0f,  0.0f, 1.0f
	};


	//2 创建唯一的vbo
	GLuint vbo = 0;
	GL_CALL(glGenBuffers(1, &vbo));
	GL_CALL(glBindBuffer(GL_ARRAY_BUFFER, vbo));
	GL_CALL(glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW));

	//3 创建并绑定vao
	GL_CALL(glGenVertexArrays(1, &vao));
	GL_CALL(glBindVertexArray(vao));


	GL_CALL(glBindBuffer(GL_ARRAY_BUFFER, vbo));
	//4 为vao加入位置和颜色的描述信息
	//4.1 位置描述信息
	GL_CALL(glEnableVertexAttribArray(0));
	GL_CALL(glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0));

	//4.2 颜色描述信息
	GL_CALL(glEnableVertexAttribArray(1));
	GL_CALL(glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)(3 * sizeof(float))));

	//5 扫尾工作：解绑当前vao
	glBindVertexArray(0);
}

void prepareVAOForGLTriangles() {
	//1 准备positions
	float positions[] = {
		-0.5f, -0.5f, 0.0f,
		0.5f, -0.5f, 0.0f,
		0.0f,  0.5f, 0.0f,
		0.5f,  0.5f, 0.0f,
		0.8f,  0.8f, 0.0f,
		0.8f,  0.0f, 0.0f
	};


	//2  posVbo
	GLuint posVbo;
	glGenBuffers(1, &posVbo);

	glBindBuffer(GL_ARRAY_BUFFER, posVbo);
	glBufferData(GL_ARRAY_BUFFER, sizeof(positions), positions, GL_STATIC_DRAW);

	//3 生成vao并且绑定
	glGenVertexArrays(1, &vao);
	glBindVertexArray(vao);

	//4 描述位置属性
	glBindBuffer(GL_ARRAY_BUFFER, posVbo);
	glEnableVertexAttribArray(0);
	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);

	glBindVertexArray(0);
}

void prepareShader() {
	//1 完成vs与fs的源代码，并且装入字符串
	const char* vertexShaderSource =
		"#version 330 core\n"
		"layout (location = 0) in vec3 aPos;\n"
		"void main()\n"
		"{\n"
		"   gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);\n"
		"}\0";
	const char* fragmentShaderSource =
		"#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";


	//2 创建Shader程序（vs、fs）
	GLuint vertex, fragment;
	vertex = glCreateShader(GL_VERTEX_SHADER);
	fragment = glCreateShader(GL_FRAGMENT_SHADER);


	//3 为shader程序输入shader代码
	glShaderSource(vertex, 1, &vertexShaderSource, NULL);
	glShaderSource(fragment, 1, &fragmentShaderSource, NULL);

	int success = 0;
	char infoLog[1024];
	//4 执行shader代码编译 
	glCompileShader(vertex);
	//检查vertex编译结果
	glGetShaderiv(vertex, GL_COMPILE_STATUS, &success);
	if (!success) {
		glGetShaderInfoLog(vertex, 1024, NULL, infoLog);
		std::cout << "Error: SHADER COMPILE ERROR --VERTEX" << "\n" << infoLog << std::endl;
	}

	glCompileShader(fragment);
	//检查fragment编译结果
	glGetShaderiv(fragment, GL_COMPILE_STATUS, &success);
	if (!success) {
		glGetShaderInfoLog(fragment, 1024, NULL, infoLog);
		std::cout << "Error: SHADER COMPILE ERROR --FRAGMENT" << "\n" << infoLog << std::endl;
	}

	//5 创建一个Program壳子
	program = glCreateProgram();

	//6 将vs与fs编译好的结果放到program这个壳子里
	glAttachShader(program, vertex);
	glAttachShader(program, fragment);

	//7 执行program的链接操作，形成最终可执行shader程序
	glLinkProgram(program);

	//检查链接错误
	glGetProgramiv(program, GL_LINK_STATUS, &success);
	if (!success) {
		glGetProgramInfoLog(program, 1024, NULL, infoLog);
		std::cout << "Error: SHADER LINK ERROR " << "\n" << infoLog << std::endl;
	}

	//清理
	glDeleteShader(vertex);
	glDeleteShader(fragment);
}

void render() {
	//执行opengl画布清理操作
	GL_CALL(glClear(GL_COLOR_BUFFER_BIT));

	//1 绑定当前的program
	glUseProgram(program);

	//2 绑定当前的vao
	glBindVertexArray(vao);

	//3 发出绘制指令
	glDrawArrays(GL_TRIANGLE_FAN, 0, 6);
	// glDrawArrays(GL_TRIANGLES, 0, 6);
	// glDrawArrays(GL_LINE_STRIP, 0, 6);
}


int main() {
	if (!app->init(800, 600)) {
		return -1;
	}

	app->setResizeCallback(OnResize);
	app->setKeyBoardCallback(OnKey);

	//设置opengl视口以及清理颜色
	GL_CALL(glViewport(0, 0, 800, 600));
	GL_CALL(glClearColor(0.2f, 0.3f, 0.3f, 1.0f));
	prepareShader();
	// prepareInterleavedBuffer();
	prepareVAOForGLTriangles();
	while (app->update()) {
		render();
	}
	app->destroy();
	return 0;
}

5.绘制直线：GL_LINES模式

运行

关键代码

cpp 复制代码 
glDrawArrays(GL_LINES, 0, 6);

6.绘制直线：GL_LINES_STRIP模式

运行

关键代码

cpp 复制代码 
glDrawArrays(GL_LINE_STRIP, 0, 6);

main.cpp

cpp 复制代码 
#include <iostream>

#define DEBUG

//注意：glad头文件必须在glfw引用之前引用
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <string>
#include <assert.h>//断言
#include "wrapper/checkError.h"
#include "application/Application.h"

/*
*┌────────────────────────────────────────────────┐
*│　目	   标： 学习glDrawArrays进行绘制命令
*│　讲    师： 赵新政(Carma Zhao)
*│　拆分目标：
*│
*│　		1  采用GL_TRANGLES进行绘制
*				** 这里大家可以缩放窗体，实验NDC坐标的作用

*│　		2  prepareVAOForGLTriangles:构建四个顶点的vao
*│　		3  测试Triangle的三种mode：TRIANGLES  TRIANGLE_STRIP TRIANGLE_FAN
*│　		4  测试Line的二种mode：LINES  LINE_STRIP
*└────────────────────────────────────────────────┘
*/

GLuint vao, program;


void OnResize(int width, int height) {
	GL_CALL(glViewport(0, 0, width, height));
	std::cout << "OnResize" << std::endl;
}

void OnKey(int key, int action, int mods) {
	std::cout << key << std::endl;
}

void prepareSingleBuffer() {
	//1 准备positions colors数据
	float positions[] = {
		   -0.5f, -0.5f, 0.0f,
			0.5f, -0.5f, 0.0f,
			0.0f,  0.5f, 0.0f
	};
	float colors[] = {
	   1.0f, 0.0f, 0.0f,
	   0.0f, 1.0f, 0.0f,
	   0.0f,  0.0f, 1.0f
	};


	//2 使用数据生成两个vbo posVbo， colorVbo
	GLuint posVbo, colorVbo;
	glGenBuffers(1, &posVbo);
	glGenBuffers(1, &colorVbo);

	glBindBuffer(GL_ARRAY_BUFFER, posVbo);
	glBufferData(GL_ARRAY_BUFFER, sizeof(positions), positions, GL_STATIC_DRAW);

	glBindBuffer(GL_ARRAY_BUFFER, colorVbo);
	glBufferData(GL_ARRAY_BUFFER, sizeof(colors), colors, GL_STATIC_DRAW);

	//3 生成vao并且绑定
	GLuint vao = 0;
	glGenVertexArrays(1, &vao);
	glBindVertexArray(vao);

	//4 分别将位置/颜色属性的描述信息加入vao当中
	//4.1描述位置属性
	glBindBuffer(GL_ARRAY_BUFFER, posVbo);//只有绑定了posVbo，下面的属性描述才会与此vbo相关
	glEnableVertexAttribArray(0);
	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);

	//4.2 描述颜色属性
	glBindBuffer(GL_ARRAY_BUFFER, colorVbo);
	glEnableVertexAttribArray(1);
	glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);

	glBindVertexArray(0);
}


void prepareInterleavedBuffer() {
	//1 准备好Interleaved数据（位置+颜色）
	float vertices[] = {
		   -0.5f, -0.5f, 0.0f,  1.0f, 0.0f, 0.0f,
			0.5f, -0.5f, 0.0f,  0.0f, 1.0f, 0.0f,
			0.0f,  0.5f, 0.0f,  0.0f,  0.0f, 1.0f
	};


	//2 创建唯一的vbo
	GLuint vbo = 0;
	GL_CALL(glGenBuffers(1, &vbo));
	GL_CALL(glBindBuffer(GL_ARRAY_BUFFER, vbo));
	GL_CALL(glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW));

	//3 创建并绑定vao
	GL_CALL(glGenVertexArrays(1, &vao));
	GL_CALL(glBindVertexArray(vao));


	GL_CALL(glBindBuffer(GL_ARRAY_BUFFER, vbo));
	//4 为vao加入位置和颜色的描述信息
	//4.1 位置描述信息
	GL_CALL(glEnableVertexAttribArray(0));
	GL_CALL(glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0));

	//4.2 颜色描述信息
	GL_CALL(glEnableVertexAttribArray(1));
	GL_CALL(glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)(3 * sizeof(float))));

	//5 扫尾工作：解绑当前vao
	glBindVertexArray(0);
}

void prepareVAOForGLTriangles() {
	//1 准备positions
	float positions[] = {
		-0.5f, -0.5f, 0.0f,
		0.5f, -0.5f, 0.0f,
		0.0f,  0.5f, 0.0f,
		0.5f,  0.5f, 0.0f,
		0.8f,  0.8f, 0.0f,
		0.8f,  0.0f, 0.0f
	};


	//2  posVbo
	GLuint posVbo;
	glGenBuffers(1, &posVbo);

	glBindBuffer(GL_ARRAY_BUFFER, posVbo);
	glBufferData(GL_ARRAY_BUFFER, sizeof(positions), positions, GL_STATIC_DRAW);

	//3 生成vao并且绑定
	glGenVertexArrays(1, &vao);
	glBindVertexArray(vao);

	//4 描述位置属性
	glBindBuffer(GL_ARRAY_BUFFER, posVbo);
	glEnableVertexAttribArray(0);
	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);

	glBindVertexArray(0);
}

void prepareShader() {
	//1 完成vs与fs的源代码，并且装入字符串
	const char* vertexShaderSource =
		"#version 330 core\n"
		"layout (location = 0) in vec3 aPos;\n"
		"void main()\n"
		"{\n"
		"   gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);\n"
		"}\0";
	const char* fragmentShaderSource =
		"#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";


	//2 创建Shader程序（vs、fs）
	GLuint vertex, fragment;
	vertex = glCreateShader(GL_VERTEX_SHADER);
	fragment = glCreateShader(GL_FRAGMENT_SHADER);


	//3 为shader程序输入shader代码
	glShaderSource(vertex, 1, &vertexShaderSource, NULL);
	glShaderSource(fragment, 1, &fragmentShaderSource, NULL);

	int success = 0;
	char infoLog[1024];
	//4 执行shader代码编译 
	glCompileShader(vertex);
	//检查vertex编译结果
	glGetShaderiv(vertex, GL_COMPILE_STATUS, &success);
	if (!success) {
		glGetShaderInfoLog(vertex, 1024, NULL, infoLog);
		std::cout << "Error: SHADER COMPILE ERROR --VERTEX" << "\n" << infoLog << std::endl;
	}

	glCompileShader(fragment);
	//检查fragment编译结果
	glGetShaderiv(fragment, GL_COMPILE_STATUS, &success);
	if (!success) {
		glGetShaderInfoLog(fragment, 1024, NULL, infoLog);
		std::cout << "Error: SHADER COMPILE ERROR --FRAGMENT" << "\n" << infoLog << std::endl;
	}

	//5 创建一个Program壳子
	program = glCreateProgram();

	//6 将vs与fs编译好的结果放到program这个壳子里
	glAttachShader(program, vertex);
	glAttachShader(program, fragment);

	//7 执行program的链接操作，形成最终可执行shader程序
	glLinkProgram(program);

	//检查链接错误
	glGetProgramiv(program, GL_LINK_STATUS, &success);
	if (!success) {
		glGetProgramInfoLog(program, 1024, NULL, infoLog);
		std::cout << "Error: SHADER LINK ERROR " << "\n" << infoLog << std::endl;
	}

	//清理
	glDeleteShader(vertex);
	glDeleteShader(fragment);
}

void render() {
	//执行opengl画布清理操作
	GL_CALL(glClear(GL_COLOR_BUFFER_BIT));

	//1 绑定当前的program
	glUseProgram(program);

	//2 绑定当前的vao
	glBindVertexArray(vao);

	//3 发出绘制指令
	glDrawArrays(GL_LINE_STRIP, 0, 6);
	// glDrawArrays(GL_TRIANGLES, 0, 6);
	// glDrawArrays(GL_LINE_STRIP, 0, 6);
}


int main() {
	if (!app->init(800, 600)) {
		return -1;
	}

	app->setResizeCallback(OnResize);
	app->setKeyBoardCallback(OnKey);

	//设置opengl视口以及清理颜色
	GL_CALL(glViewport(0, 0, 800, 600));
	GL_CALL(glClearColor(0.2f, 0.3f, 0.3f, 1.0f));
	prepareShader();
	// prepareInterleavedBuffer();
	prepareVAOForGLTriangles();
	while (app->update()) {
		render();
	}
	app->destroy();
	return 0;
}

7.其他代码文件

7.1.主CMakeLists.txt

cmake 复制代码 
# 指定 CMake 最低版本
cmake_minimum_required(VERSION 3.12)

# 项目名称
project(OpenGL_Lecture)

# 设置 C++ 标准
set(CMAKE_CXX_STANDARD 17)

# 包含头文件目录
include_directories(
    ${CMAKE_CURRENT_SOURCE_DIR}/thirdParty/include
    /usr/include
)

# 包含库文件目录
link_directories(
    ${CMAKE_CURRENT_SOURCE_DIR}/thirdParty/lib
    /usr/lib/x86_64-linux-gnu
)

# 设置 CMAKE_PREFIX_PATH 以找到 GLFW
set(CMAKE_PREFIX_PATH "/usr/local/lib/cmake/glfw3")
set(GLFW_DIR "/usr/local/lib/cmake/glfw3")

# 查找 GLFW3 库
find_package(glfw3 REQUIRED CONFIG)

add_subdirectory(wrapper)
add_subdirectory(application)

# 添加可执行文件
add_executable(openglStudy "main.cpp" "glad.c")

# 链接库
target_link_libraries(openglStudy glfw wrapper app)

7.2.application\CMakeLists.txt

cmake 复制代码 
#递归将本文件夹下所有cpp放到FUNCS中
file(GLOB_RECURSE APP ./  *.cpp)

#将FUNCS中所有cpp编译为funcs这个lib库
add_library(app ${APP} )

target_include_directories(app PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})
target_link_libraries(app PRIVATE glfw)

7.3.application\Application.h

cpp 复制代码 
#pragma once 

/*
*┌────────────────────────────────────────────────┐
*│　目	   标： 封装Application（表示了当前应用程序本身）
*│　讲    师： 赵新政(Carma Zhao)
*│　拆分目标：
*│
*│　		1	单例类（全局唯一实例）
*│　		2	成员变量 + 成员函数
*				2.1 成员函数-init（初始化）
*				2.2 成员函数-update（每一帧执行）
*				2.3 成员函数-destroy（结尾执行）
*│　		3	响应回调函数(Resize)
*				3.1 声明一个函数指针ResizeCallback
*				3.2 声明一个ResizeCallback类型的成员变量
*				3.3 声明一个SetResizeCallback的函数 ，设置窗体变化响应回调函数
*				3.4 声明一个static的静态函数，用于响应glfw窗体变化
*				3.5 将静态函数设置到glfw的监听Resize监听当中
*				3.6 * 学会使用glfw的UserPointer
*│　		4	响应键盘消息函数(KeyBoard)
*				3.1 声明一个static的静态函数，用于响应glfw的键盘事件
*				3.2 将静态函数设置到glfw的监听KeyCallback监听当中
*				3.3 声明一个函数指针KeyBoardCallback
*				3.4 声明一个KeyBoardCallback类型的成员变量
*				3.5 声明一个SetKeyBoardCallback的函数 ，设置键盘响应回调函数
*				3.6 * 学会使用glfw的UserPointer
*└────────────────────────────────────────────────┘
*/
#include <iostream>


#define app Application::getInstance()

class GLFWwindow;

using ResizeCallback = void(*)(int width, int height);
using KeyBoardCallback = void(*)(int key, int action, int mods);

class Application {
public:
	~Application();
	
	//用于访问实例的静态函数
	static Application* getInstance();

	bool init(const int& width = 800, const int& height = 600);

	bool update();

	void destroy();


	uint32_t getWidth()const { return mWidth; }
	uint32_t getHeight()const { return mHeight; }

	void setResizeCallback(ResizeCallback callback) { mResizeCallback = callback; }
	void setKeyBoardCallback(KeyBoardCallback callback) { mKeyBoardCallback = callback; }

private:
	//C++类内函数指针
	static void frameBufferSizeCallback(GLFWwindow* window, int width, int height);
	static void keyCallback(GLFWwindow* window, int key, int scancode, int action, int mods);

private:
	//全局唯一的静态变量实例
	static Application* mInstance;

	uint32_t mWidth{ 0 };
	uint32_t mHeight{ 0 };
	GLFWwindow* mWindow{ nullptr };

	ResizeCallback mResizeCallback{ nullptr };
	KeyBoardCallback mKeyBoardCallback{ nullptr };

	Application();
};

7.4.application\Application.cpp

cpp 复制代码 
#include "Application.h"
#include<glad/glad.h>
#include<GLFW/glfw3.h>


//初始化Application的静态变量
Application* Application::mInstance = nullptr;
Application* Application::getInstance() {
	//如果mInstance已经实例化了（new出来了），就直接返回
	//否则需要先new出来，再返回
	if (mInstance == nullptr) {
		mInstance = new Application();
	}

	return mInstance;
}

Application::Application() {

}

Application::~Application() {

}


bool Application::init(const int& width, const int& height) {
	mWidth = width;
	mHeight = height;

	//1 初始化GLFW基本环境
	glfwInit();
	//1.1 设置OpenGL主版本号、次版本号
	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
	//1.2 设置OpenGL启用核心模式（非立即渲染模式）
	glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

	//2 创建窗体对象
	mWindow = glfwCreateWindow(mWidth, mHeight, "OpenGLStudy", NULL, NULL);
	if (mWindow == NULL) {
		return false;
	}

	//**设置当前窗体对象为OpenGL的绘制舞台
	glfwMakeContextCurrent(mWindow);

	if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) {
		std::cout << "Failed to initialize GLAD" << std::endl;
		return false;
	}
	
	glfwSetFramebufferSizeCallback(mWindow, frameBufferSizeCallback);

	//this就是当前全局唯一的Application对象
	glfwSetWindowUserPointer(mWindow, this);

	//键盘响应
	glfwSetKeyCallback(mWindow, keyCallback);

	return true;
}

bool Application::update() {
	if (glfwWindowShouldClose(mWindow)) {
		return false;
	}

	//接收并分发窗体消息
	//检查消息队列是否有需要处理的鼠标、键盘等消息
	//如果有的话就将消息批量处理，清空队列
	glfwPollEvents();

	//切换双缓存
	glfwSwapBuffers(mWindow);

	return true;
}

void Application::destroy() {
	//退出程序前做相关清理
	glfwTerminate();
}


void Application::frameBufferSizeCallback(GLFWwindow* window, int width, int height) {
	std::cout << "Resize" << std::endl;

	Application* self = (Application*)glfwGetWindowUserPointer(window);
	if (self->mResizeCallback != nullptr) {
		self->mResizeCallback(width, height);
	}

	//if (Application::getInstance()->mResizeCallback != nullptr) {
	//	Application::getInstance()->mResizeCallback(width, height);
	//}
}

void Application::keyCallback(GLFWwindow* window, int key, int scancode, int action, int mods) {
	Application* self = (Application*)glfwGetWindowUserPointer(window);
	if (self->mKeyBoardCallback != nullptr) {
		self->mKeyBoardCallback(key, action, mods);
	}
}

7.5.wrapper\CMakeLists.txt

cmake 复制代码 
#递归将本文件夹下所有cpp放到FUNCS中
file(GLOB_RECURSE WRAPPER ./  *.cpp)

#将FUNCS中所有cpp编译为funcs这个lib库
add_library(wrapper ${WRAPPER} )

target_include_directories(wrapper PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})
target_link_libraries(wrapper PRIVATE glfw)

7.6.wrapper\checkError.h

cpp 复制代码 
#pragma once 

//预编译宏
#ifdef DEBUG
#define GL_CALL(func)  func;checkError();
#else
#define GL_CALL(func) 
#endif 


void checkError();

7.7.wrapper\checkError.cpp

cpp 复制代码 
#include "checkError.h"
#include <glad/glad.h>
#include <string>
#include <iostream>
#include <assert.h>

void checkError() {
	GLenum errorCode = glGetError();
	std::string error = "";
	if (errorCode != GL_NO_ERROR) {
		switch (errorCode)
		{
		case GL_INVALID_ENUM: error = "INVALID_ENUM"; break;
		case GL_INVALID_VALUE:  error = "INVALID_VALUE"; break;
		case GL_INVALID_OPERATION: error = "INVALID_OPERATION"; break;
		case GL_OUT_OF_MEMORY: error = "OUT OF MEMORY"; break;
		default:
			error = "UNKNOWN";
			break;
		}
		std::cout << error << std::endl;

		//assert会根据传入的bool值，来决定程序是否停止
		//true：程序顺利运行
		//false：程序会断死
		assert(false);
	}
}
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