OpenGL笔记（4）C++文件流读取shader着色器

前言

由于前面写三角形时要用字符串来储存着色器代码的做法太不优雅了，所以决定用文件流读取

创建文件

在vs的解决方案资源管理器中，在资源文件夹下创建两个txt文件，名字为vertexSource.vs和fragmentSource.fs，后缀名.vs代表是顶点着色器文件，.fs代表片段着色器文件。
然后写入着色器代码

#version 330 core
layout (location = 0) in vec3 aPos;

void main()
{
    gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);
}

#version 330 core
out vec4 FragColor;

void main()
{
    FragColor = vec4(1.0f, 0.5f, 0.2f, 1.0f);
} 

Shader类

为保持良好的编程习惯，新建一个shader.h头文件和一个shader.cpp，在头文件中写入类变量和函数头，在cpp文件中写入实现函数的代码。

#ifndef SHADER_H
#define SHADER_H

#include <string>

class Shader
{
public :
	unsigned int ID;//Program ID
	std::string vertexString;
	std::string fragmentString;
	const char* vertexSource;
	const char* fragmentSource;
public :
	Shader(const char* vertexPath, const char* fragmentPath);
	void use();
	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;

};

#endif

#define GLEW_STATIC
#include "Shader.h"
#include <iostream>
#include <fstream>
#include <sstream>
#include <glad/glad.h>

using namespace std;

Shader::Shader(const char* vertexPath, const char* fragmentPath)
{
	ifstream vertexFile;
	ifstream fragmentFile;
	stringstream vertexSStream;
	stringstream fragmentSStream;
	


	vertexFile.exceptions(ifstream::failbit || ifstream::badbit);
	fragmentFile.exceptions(ifstream::failbit || ifstream::badbit);


	try
	{
		vertexFile.open(vertexPath);
		fragmentFile.open(fragmentPath);

		if (!vertexFile.is_open()||!fragmentFile.is_open())
		{
			throw exception("open file error");
		}
		vertexSStream << vertexFile.rdbuf();
		fragmentSStream << fragmentFile.rdbuf();

		vertexFile.close();
		fragmentFile.close();

		vertexString = vertexSStream.str();
		fragmentString = fragmentSStream.str();

		vertexSource = vertexString.c_str();
		fragmentSource = fragmentString.c_str();

		
	}
	catch (const exception& ex)
	{
		printf(ex.what());
	}

	unsigned int vertex, fragment;
	int success;
	char infoLog[512];

	vertex = glCreateShader(GL_VERTEX_SHADER);
	glShaderSource(vertex, 1, &vertexSource, NULL);
	glCompileShader(vertex);

	glGetShaderiv(vertex, GL_COMPILE_STATUS, &success);
	if (!success)
	{
		glGetShaderInfoLog(vertex, 512, NULL, infoLog);
		cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog << endl;
	}

	fragment = glCreateShader(GL_FRAGMENT_SHADER);
	glShaderSource(fragment, 1, &fragmentSource, NULL);
	glCompileShader(fragment);

	glGetShaderiv(fragment, GL_COMPILE_STATUS, &success);
	if (!success)
	{
		glGetShaderInfoLog(fragment, 512, NULL, infoLog);
		cout << "ERROR::SHADER::FRAGMENT::COMPILATION_FAILED\n" << infoLog << endl;
	}


	ID = glCreateProgram();
	glAttachShader(ID, vertex);
	glAttachShader(ID, fragment);
	glLinkProgram(ID);

	glGetProgramiv(ID, GL_LINK_STATUS, &success);
	if (!success)
	{
		glGetProgramInfoLog(ID, 512, NULL, infoLog);
		cout << "ERROR::SHADER::PROGRAM::LINKING_FAILED\n" << infoLog << endl;
	}

	glDeleteShader(vertex);
	glDeleteShader(fragment);
}

void Shader::use()
{
	glUseProgram(ID);
}

void Shader::setBool(const string& name, bool value) const
{
	glUniform1i(glGetUniformLocation(ID, name.c_str()), (int)value);
}

void Shader::setInt(const string& name, int value) const
{
	glUniform1i(glGetUniformLocation(ID, name.c_str()), value);
}

void Shader::setFloat(const string& name, float value) const
{
	glUniform1i(glGetUniformLocation(ID, name.c_str()), value);
}

那么shader类已经写好了。

使用

在渲染循环里写入

Shader myShader;
myShader.use();