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triangle.cpp
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triangle.cpp
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#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <iostream>
// 窗口大小回调函数
void framebuffer_size_callback(GLFWwindow *, int, int);
//用户输入
void processInput(GLFWwindow *);
//glfw初始化
void glfw_init();
//检测窗口
int check_window(GLFWwindow *);
// 加载glad
int load_opengl_fun_ptr();
// 编译着色器
unsigned int compile_shader();
// 绘制
void draw_my_triangle(GLFWwindow *window, unsigned int shaderProgram);
// 定义屏幕宽和高
const unsigned int SCR_WIDTH = 800;
const unsigned int SCR_HEIGHT = 600;
int main() {
// 初始化glfw库
glfw_init();
//MacOS
#ifdef __APPLE__
glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
#endif
// 创建窗口
GLFWwindow *window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "绘制三角形", NULL, NULL);
// 检测窗口
check_window(window);
// 设置当前窗口context为主线程
glfwMakeContextCurrent(window);
// 设置窗口大小
glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
// 加载opengl函数指针
load_opengl_fun_ptr();
// 编译着色器
auto shaderProgram = compile_shader();
// 绘制
draw_my_triangle(window, shaderProgram);
// 清除glfw资源
glfwTerminate();
return 0;
}
// process all input: query GLFW whether relevant keys are pressed/released this frame and react accordingly
void processInput(GLFWwindow *window) {
if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
glfwSetWindowShouldClose(window, true);
}
// glfw: whenever the window size changed (by OS or user resize) this callback function executes
void framebuffer_size_callback(GLFWwindow *window, int width, int height) {
// make sure the viewport matches the new window dimensions; note that width and
// height will be significantly larger than specified on retina displays.
glViewport(0, 0, width, height);
}
void glfw_init() {
// glfw初始化
glfwInit();
// glfw主版本号
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
// glfw次版本号
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
// 使用glfw核心模式
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
}
int check_window(GLFWwindow *window) {
if (window == NULL) {
std::cout << "Failed to create GLFW window" << std::endl;
glfwTerminate();
return -1;
}
return 0;
}
// glad: load all OpenGL function pointers
int load_opengl_fun_ptr() {
if (!gladLoadGLLoader((GLADloadproc) glfwGetProcAddress)) {
std::cout << "Failed to initialize GLAD" << std::endl;
return -1;
}
return 0;
}
/**
* 编译着色器
* @return
*/
unsigned int compile_shader() {
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(0.2f, 0.0f, 0.5f, 1.0f);\n"
"}\n\0";
// build and compile our shader program
// ------------------------------------
// vertex shader
unsigned int vertexShader = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
glCompileShader(vertexShader);
// check for shader compile errors
int success;
char infoLog[512];
glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);
if (!success) {
glGetShaderInfoLog(vertexShader, 512, NULL, infoLog);
std::cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog << std::endl;
}
// fragment shader
unsigned int fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
glCompileShader(fragmentShader);
// check for shader compile errors
glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &success);
if (!success) {
glGetShaderInfoLog(fragmentShader, 512, NULL, infoLog);
std::cout << "ERROR::SHADER::FRAGMENT::COMPILATION_FAILED\n" << infoLog << std::endl;
}
// link shaders
unsigned int shaderProgram = glCreateProgram();
glAttachShader(shaderProgram, vertexShader);
glAttachShader(shaderProgram, fragmentShader);
glLinkProgram(shaderProgram);
// check for linking errors
glGetProgramiv(shaderProgram, GL_LINK_STATUS, &success);
if (!success) {
glGetProgramInfoLog(shaderProgram, 512, NULL, infoLog);
std::cout << "ERROR::SHADER::PROGRAM::LINKING_FAILED\n" << infoLog << std::endl;
}
glDeleteShader(vertexShader);
glDeleteShader(fragmentShader);
return shaderProgram;
}
void draw_my_triangle(GLFWwindow *window, unsigned int shaderProgram) {
float vertices[] = {
-0.5f, -0.5f, 0.0f, // left
0.5f, -0.5f, 0.0f, // right
0.0f, 0.5f, 0.0f // top
};
unsigned int VBO, VAO;
glGenVertexArrays(1, &VAO);
glGenBuffers(1, &VBO);
glBindVertexArray(VAO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void *) 0);
glEnableVertexAttribArray(0);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindVertexArray(0);
while (!glfwWindowShouldClose(window)) {
// input
// -----
processInput(window);
// render
// ------
glClearColor(0.6f, 0.7f, 0.0f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
// draw our first triangle
glUseProgram(shaderProgram);
glBindVertexArray(
VAO); // seeing as we only have a single VAO there's no need to bind it every time, but we'll do so to keep things a bit more organized
glDrawArrays(GL_TRIANGLES, 0, 3);
// glBindVertexArray(0); // no need to unbind it every time
// glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.)
// -------------------------------------------------------------------------------
glfwSwapBuffers(window);
glfwPollEvents();
}
// optional: de-allocate all resources once they've outlived their purpose:
// ------------------------------------------------------------------------
glDeleteVertexArrays(1, &VAO);
glDeleteBuffers(1, &VBO);
glDeleteProgram(shaderProgram);
}