shader.h

#pragma once
#ifndef SHADER_H
#define SHADER_H

#include <glad/glad.h> // 包含glad来获取所有的必须OpenGL头文件
#include <glm/glm.hpp>

#include <string>
#include <fstream>
#include <sstream>
#include <iostream>


class Shader
{
public:
	// 程序ID
	unsigned int ID;

	// 构造器读取并构建着色器
	Shader(const char* vertexPath, const char* fragmentPath)
	{
		// 1. 从文件路径中获取顶点/片段着色器
		std::string vertexCode;
		std::string fragmentCode;
		std::ifstream vShaderFile;
		std::ifstream fShaderFile;
		// 保证ifstream对象可以抛出异常：
		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;
			// 读取文件的缓冲内容到数据流中
			vShaderStream << vShaderFile.rdbuf();
			fShaderStream << fShaderFile.rdbuf();
			// 关闭文件处理器
			vShaderFile.close();
			fShaderFile.close();
			// 转换数据流到string
			vertexCode = vShaderStream.str();
			fragmentCode = fShaderStream.str();
		}
		catch (std::ifstream::failure e)
		{
			std::cout << "ERROR::SHADER::FILE_NOT_SUCCESFULLY_READ" << std::endl;
		}
		const char* vShaderCode = vertexCode.c_str();
		const char* fShaderCode = fragmentCode.c_str();

		// 2. 编译着色器
		unsigned int vertex, fragment;
		int success;
		char infoLog[512];

		// 顶点着色器
		vertex = glCreateShader(GL_VERTEX_SHADER);
		glShaderSource(vertex, 1, &vShaderCode, NULL);
		glCompileShader(vertex);
		// 打印编译错误（如果有的话）
		glGetShaderiv(vertex, GL_COMPILE_STATUS, &success);
		if (!success)
		{
			glGetShaderInfoLog(vertex, 512, NULL, infoLog);
			std::cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog << std::endl;
		};

		// 片段着色器也类似
		fragment = glCreateShader(GL_FRAGMENT_SHADER);
		glShaderSource(fragment, 1, &fShaderCode, NULL);
		glCompileShader(fragment);
		glGetShaderiv(fragment, GL_COMPILE_STATUS, &success);
		if (!success)
		{
			glGetShaderInfoLog(fragment, 512, NULL, infoLog);
			std::cout << "ERROR::SHADER::PIXEL::COMPILATION_FAILED\n" << infoLog << std::endl;
		}

		// 着色器程序
		ID = glCreateProgram();
		glAttachShader(ID, vertex);
		glAttachShader(ID, fragment);
		glLinkProgram(ID);
		// 打印连接错误（如果有的话）
		glGetProgramiv(ID, GL_LINK_STATUS, &success);
		if (!success)
		{
			glGetProgramInfoLog(ID, 512, NULL, infoLog);
			std::cout << "ERROR::SHADER::PROGRAM::LINKING_FAILED\n" << infoLog << std::endl;
		}

		// 删除着色器，它们已经链接到我们的程序中了，已经不再需要了
		glDeleteShader(vertex);
		glDeleteShader(fragment);
	}
	// 使用/激活程序
	void use()
	{
		glUseProgram(ID);
	}
	// uniform工具函数
	void setBool(const std::string& name, bool value) const
	{
		glUniform1i(glGetUniformLocation(ID, name.c_str()), (int)value);
	}
	void setInt(const std::string& name, int value) const
	{
		glUniform1i(glGetUniformLocation(ID, name.c_str()), value);
	}
	void setFloat(const std::string& name, float value) const
	{
		glUniform1f(glGetUniformLocation(ID, name.c_str()), value);
	}
	void setMat4(const std::string& name, const glm::mat4 value) const
	{
		glUniformMatrix4fv(glGetUniformLocation(ID, name.c_str()), 1, GL_FALSE, &value[0][0]);
	}
};

#endif