GLFW简介_r18公主连接[通俗易懂]

GLFW 是配合 OpenGL 使用的轻量级工具程序库，缩写自 Graphics Library Framework（图形库框架）。GLFW 的主要功能是创建并管理窗口和 OpenGL 上下文，同时还提供了处理手柄、键盘、鼠标输入的功能。有类似功能的库还有 GLUT和 SDL。

Build

• 下载

$ git clone https://github.com/glfw/glfw.git

• 编译 && 安装

$ cd glfw && mkdir build && cd build && cmake .. && make -j8 && make install

Getting started

可以阅读Getting started来理解GLFW3的使用，通过一个例子讲解如何使用GLFW3来创建一个窗口和绘制一个旋转的三角形，当关闭窗口时如何释放资源。

#include <glad/glad.h> // 需要依赖glad这个库
#define GLFW_INCLUDE_NONE
#include <GLFW/glfw3.h>
#include "linmath.h" // 这个是glfw3里面的一个文件，可以从里面拿到，不过编译安装的时候不会安装到系统目录
 
#include <stdlib.h>
#include <stdio.h>
 
static const struct
{ 
   
    float x, y;
    float r, g, b;
} vertices[3] =
{ 
   
    { 
    -0.6f, -0.4f, 1.f, 0.f, 0.f },
    { 
     0.6f, -0.4f, 0.f, 1.f, 0.f },
    { 
      0.f,  0.6f, 0.f, 0.f, 1.f }
};
 
// 一个GLES Vertex Shader
static const char* vertex_shader_text =
"#version 110\n"
"uniform mat4 MVP;\n"
"attribute vec3 vCol;\n"
"attribute vec2 vPos;\n"
"varying vec3 color;\n"
"void main()\n"
"{\n"
" gl_Position = MVP * vec4(vPos, 0.0, 1.0);\n"
" color = vCol;\n"
"}\n";
 
// 一个GLES Fragment Shader
static const char* fragment_shader_text =
"#version 110\n"
"varying vec3 color;\n"
"void main()\n"
"{\n"
" gl_FragColor = vec4(color, 1.0);\n"
"}\n";
 
static void error_callback(int error, const char* description)
{ 
   
    fprintf(stderr, "Error: %s\n", description);
}
 
static void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods)
{ 
   
    if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
        glfwSetWindowShouldClose(window, GLFW_TRUE);
}
 
int main(void)
{ 
   
    GLFWwindow* window;
    GLuint vertex_buffer, vertex_shader, fragment_shader, program;
    GLint mvp_location, vpos_location, vcol_location;
 
    // 设置错误回调
    glfwSetErrorCallback(error_callback);
 
    if (!glfwInit())
        exit(EXIT_FAILURE);
 
    // 设置使用2.0版本的GL
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 2);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);
 
    // 创建一个窗口，窗口名字为"Simple example"
    window = glfwCreateWindow(640, 480, "Simple example", NULL, NULL);
    if (!window) { 
   
        glfwTerminate();
        exit(EXIT_FAILURE);
    }
 
    // 设置按键回调
    glfwSetKeyCallback(window, key_callback);
 
    // 绑定当前线程的Content为window
    glfwMakeContextCurrent(window);
    // glfwGetProcAddress是对gl库dlsym的封装，gladLoadGLLoader会去尝试加载所有版本的gl库
    gladLoadGLLoader((GLADloadproc)glfwGetProcAddress);
    // 设置swap间隔
    glfwSwapInterval(1);
 
    // 创建顶点buffer，并上传顶点
    glGenBuffers(1, &vertex_buffer);
    glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
 
    // 创建，加载，编译Fragment Shader
    vertex_shader = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertex_shader, 1, &vertex_shader_text, NULL);
    glCompileShader(vertex_shader);
    // 创建，加载，编译Vertex Shader
    fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fragment_shader, 1, &fragment_shader_text, NULL);
    glCompileShader(fragment_shader);
    // 创建，链接Program
    program = glCreateProgram();
    glAttachShader(program, vertex_shader);
    glAttachShader(program, fragment_shader);
    glLinkProgram(program);
    // 获取shader中顶点对应的location
    mvp_location = glGetUniformLocation(program, "MVP");
    vpos_location = glGetAttribLocation(program, "vPos");
    vcol_location = glGetAttribLocation(program, "vCol");
     // 设置顶点的值
    glEnableVertexAttribArray(vpos_location);
    glVertexAttribPointer(vpos_location, 2, GL_FLOAT, GL_FALSE, sizeof(vertices[0]), (void*) 0);
    glEnableVertexAttribArray(vcol_location);
    glVertexAttribPointer(vcol_location, 3, GL_FLOAT, GL_FALSE, sizeof(vertices[0]), (void*) (sizeof(float) * 2));
     // 实时获取窗口的大小，根据时间实时旋转三角形
    while (!glfwWindowShouldClose(window)) { 
   
        float ratio;
        int width, height;
        mat4x4 m, p, mvp;
 
        glfwGetFramebufferSize(window, &width, &height);
        ratio = width / (float) height;
 
        glViewport(0, 0, width, height);
        glClear(GL_COLOR_BUFFER_BIT);
 
        mat4x4_identity(m);
        mat4x4_rotate_Z(m, m, (float) glfwGetTime());
        mat4x4_ortho(p, -ratio, ratio, -1.f, 1.f, 1.f, -1.f);
        mat4x4_mul(mvp, p, m);
 
        glUseProgram(program);
        glUniformMatrix4fv(mvp_location, 1, GL_FALSE, (const GLfloat*) mvp);
        glDrawArrays(GL_TRIANGLES, 0, 3);
 
        glfwSwapBuffers(window);
        glfwPollEvents();
    }
    // 销毁资源
    glfwDestroyWindow(window);
    glfwTerminate();
    exit(EXIT_SUCCESS);
}

Examples

glfw/examples目录下有13个例子可以参考

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