OpenGL筆記（4）C++文件流讀取shader着色器

前言

由於前面寫三角形時要用字符串來儲存着色器代碼的做法太不優雅了，所以決定用文件流讀取

創建文件

在vs的解決方案資源管理器中，在資源文件夾下創建兩個txt文件，名字爲vertexSource.vs和fragmentSource.fs，後綴名.vs代表是頂點着色器文件，.fs代表片段着色器文件。
然後寫入着色器代碼

#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類

爲保持良好的編程習慣，新建一個shader.h頭文件和一個shader.cpp，在頭文件中寫入類變量和函數頭，在cpp文件中寫入實現函數的代碼。

#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);
}

那麼shader類已經寫好了。

使用

在渲染循環裏寫入

Shader myShader;
myShader.use();