/*
* 当需要给图形赋予真实颜色的时候,不太可能为没一个顶点指定一个颜色,通常会采用纹理贴图
* 每个顶点关联一个纹理坐标 (Texture Coordinate) 其它片段上进行片段插值
*
*/
#include <iostream>
#define STBI_NO_SIMD
#define STB_IMAGE_IMPLEMENTATION
#include "stb_image.h"
#include <glad/glad.h> // 把这个头文件放在最上面
#include <GLFW/glfw3.h>
#include <string>
#include <fstream>
#include <sstream>
#include "glm/glm.hpp"
class MyShader {
public:
unsigned int ID; // 着色器程序 ID
// 构造函数读取并构建 shader
MyShader(const char* vertexPath, const char* fragmentPath);
// 使用激活 Shader
void use();
// 设置 uniform 的工具函数
void setBool(const std::string& name, bool value) const;
void setInt(const std::string& name, int value) const;
void setFloat(const std::string& name, float value) const;
void setVec4(const std::string& name, const glm::vec4& value) const;
};
MyShader::MyShader(const char* vertexPath, const char* fragmentPath)
{
// 从文件加载 shader 的源码
// 1.0 从文件路径加载顶点 / 片段源代码
std::string vertexCode, fragmentCode;
std::ifstream vShaderFile, fShaderFile;
// 确保 ifstream 对象可以引发异常
vShaderFile.exceptions(std::ifstream::failbit | std::ifstream::badbit);
fShaderFile.exceptions(std::ifstream::failbit | std::ifstream::badbit);
try
{
// 打开文件
vShaderFile.open(vertexPath);
fShaderFile.open(fragmentPath);
std::stringstream vShaderStream, fShaderStream;
// 将文件的缓冲区内容读入流
vShaderStream << vShaderFile.rdbuf();
fShaderStream << fShaderFile.rdbuf();
// 关闭文件处理程序
vShaderFile.close();
fShaderFile.close();
// 将流转换为字符串
vertexCode = vShaderStream.str();
fragmentCode = fShaderStream.str();
}
catch (const std::ifstream::failure e)
{
std::cout << "ERROR::SHADER::FILE_NOT_SUCCESSFULLY_READ" << std::endl;
}
const char* vShaderCode = vertexCode.c_str();
const char* fShaderCode = fragmentCode.c_str();
// 编译着色器
unsigned int vertexShader, fragmentShader;
int success;
char infoLog[512];
// 顶点着色器
vertexShader = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(vertexShader, 1, &vShaderCode, nullptr);
glCompileShader(vertexShader);
glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);
if (!success) // 打印错误提示信息
{
glGetShaderInfoLog(vertexShader, 512, NULL, infoLog);
std::cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog << std::endl;
}
//片元着色器
fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(fragmentShader, 1, &fShaderCode, nullptr);
glCompileShader(fragmentShader);
glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &success);
if (!success)
{
glGetShaderInfoLog(fragmentShader, 512, NULL, infoLog);
std::cout << "ERROR::SHADER::FRAGMENT::COMPILATION_FAILED\n" << infoLog << std::endl;
}
//着色器程序
ID = glCreateProgram();
glAttachShader(ID, vertexShader);
glAttachShader(ID, fragmentShader);
glLinkProgram(ID);
glGetProgramiv(ID, GL_LINK_STATUS, &success);
if (!success)
{
glGetProgramInfoLog(ID, 512, nullptr, infoLog);
std::cout << "ERROR::SHADER::PROGRAM::LINKING_FAILED\n" << infoLog << std::endl;
}
//删除着色器
glDeleteShader(vertexShader);
glDeleteShader(fragmentShader);
}
void MyShader::use()
{
glUseProgram(ID);
}
void MyShader::setBool(const std::string& name, bool value) const
{
glUniform1i(glGetUniformLocation(ID, name.c_str()), (int)value);
}
void MyShader::setInt(const std::string& name, int value) const
{
glUniform1i(glGetUniformLocation(ID, name.c_str()), value);
}
void MyShader::setFloat(const std::string& name, float value) const
{
glUniform1i(glGetUniformLocation(ID, name.c_str()), value);
}
void MyShader::setVec4(const std::string& name, const glm::vec4& value) const
{
glUniform4fv(glGetUniformLocation(ID, name.c_str()), 1, &value[0]);
}
//响应键盘输入事件
//ESC推出窗口
void processInput(GLFWwindow* window)
{
if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
{
glfwSetWindowShouldClose(window, true);
}
}
//当用户改变窗口的大小的时候,视口也应该被调整。
//对窗口注册一个回调函数(Callback Function),它会在每次窗口大小被调整的时候被调用
void framebuffer_size_callback(GLFWwindow* window, int width, int height)
{
//glViewport函数前两个参数控制窗口左下角的位置。第三个和第四个参数控制渲染窗口的宽度和高度(像素)
glViewport(0, 0, width, height);
}
int main()
{
float vertices[] = {
// 位置 // 颜色 // 纹理坐标
0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f, // 右上
0.5f, -0.5f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f, 1.0f, // 右下
-0.5f, -0.5f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f, // 左下
-0.5f, 0.5f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 0.0f // 左上
};
unsigned int indices[] = {
0, 1, 3,
1, 2, 3,
};
/*******************************************定义常量************************************************/
//设置窗口的宽和高
const unsigned int SCR_WIDTH = 800;
const unsigned int SCR_HEIGHT = 600;
/*******************************************函数***************************************************/
//初始化GLFW
glfwInit();
// 初始化GLFW
if (!glfwInit())
{
std::cerr << "Failed to initialize GLFW" << std::endl;
return -1;
}
//声明版本与核心
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 4); //主版本号
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 6); //次版本号
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
//创建窗口并设置其大小,名称,与检测是否创建成功
GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", nullptr, nullptr);
if (window == nullptr)
{
std::cout << "Failed to create GLFW window" << std::endl;
glfwTerminate();
return -1;
}
//创建完毕之后,需要让当前窗口的环境在当前线程上成为当前环境,就是接下来的画图都会画在我们刚刚创建的窗口上
glfwMakeContextCurrent(window);
//告诉GLFW我们希望每当窗口调整大小的时候调用这个函数
glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
//glad寻找opengl的函数地址,调用opengl的函数前需要初始化glad
if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
{
std::cout << "Failed to initialize GLAD" << std::endl;
return -1;
}
// 创建一个 shader 的类
MyShader shader("shader/shader.vs", "shader/shader.fs");
unsigned int VBO, VAO, EBO;
glGenVertexArrays(1, &VAO);
glBindVertexArray(VAO); //绑定VAO对象
glGenBuffers(1, &VBO);
glGenBuffers(1, &EBO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(3 * sizeof(float)));
glEnableVertexAttribArray(1);
glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(6 * sizeof(float)));
glEnableVertexAttribArray(2);
// 绑定 EBO
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
//链接顶点属性,设置顶点属性指针
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
//以顶点属性位置值作为参数,启用顶点属性;顶点属性默认是禁用的。
glBindBuffer(GL_ARRAY_BUFFER, 0);
//glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
glBindVertexArray(0);
// 读一张纹理图像
int width, height, channels;
unsigned char* data = stbi_load("lena.jpg", &width, &height, &channels, 0);
if (data)
{
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data);
glGenerateMipmap(GL_TEXTURE_2D);
}
else
{
std::cout << "Failed to load texture" << std::endl;
}
stbi_image_free(data);
//glfwWindowShouldClose()检查窗口是否需要关闭。如果是,游戏循环就结束了,接下来我们将会清理资源,结束程序
while (!glfwWindowShouldClose(window))
{
//响应键盘输入
processInput(window);
//设置清除颜色
glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
//清除当前窗口,把颜色设置为清除颜色
glClear(GL_COLOR_BUFFER_BIT);
shader.use(); // 选择流水线
// 设置unifor 值
float timeValue = glfwGetTime();
float greenValue = sin(timeValue) / 2.0f + 0.5f;
glm::vec4 color = glm::vec4(0.0f, greenValue, 0.0f, 1.0f);
shader.setVec4("ourColor", color);
//绑定VAO
glBindVertexArray(VAO);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
//glDrawArrays(GL_TRIANGLES, 0, 3);
glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
//线框绘制
//glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
//交换颜色缓冲
glfwSwapBuffers(window);
//处理事件
glfwPollEvents();
}
//释放前面所申请的资源
glfwTerminate();
清理资源
glDeleteVertexArrays(1, &VAO);
glDeleteBuffers(1, &VBO);
glDeleteBuffers(1, &EBO);
glDeleteProgram(shader.ID);
return 0;
}
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