Shaders

main.cpp

#define GLEW_STATIC
#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <bits/stdc++.h>
#include "Shader.h"

float vertices[] = {
	// positions         // colors
	 -0.5f, -0.5f, 0.3f,  1.0f, 0.0f, 0.0f,  // bottom right
	0.5f, -0.9f, 0.0f,  0.0f, 1.0f, 0.0f,  // bottom left
	 0.0f,  0.5f, 0.0f,  0.0f, 0.0f, 1.0f,   // top 
	 0.8f, 0.8f, 0.0f, 1.0f, 0.0f, 1.0f
};

unsigned int indices[] = { // 注意索引从0开始! 
	0, 1, 2, // 第一个三角形
	2, 3, 1  // 第二个三角形
};

void HandleInput(GLFWwindow* window)
{
	if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
	{
		glfwSetWindowShouldClose(window, true);
	}
}

int main()
{

	glfwInit();
	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
	glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

	GLFWwindow* window = glfwCreateWindow(800, 600, "First Window", NULL, NULL);
	if (window == NULL)
	{
		std::cout << "Somethong wrong happen" << std::endl;
		glfwTerminate();
		return -1;
	}
	glfwMakeContextCurrent(window);

	// INIT GLEW
	glewExperimental = true;
	if (glewInit() != GLEW_OK)
	{
		std::cout << "INIT GLEW FAIL" << std::endl;
		glfwTerminate();
		return -1;
	}

	glViewport(0, 0, 800, 600);

	glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);

	// 开启面剔除
	glEnable(GL_CULL_FACE);
	glCullFace(GL_BACK);

	Shader testShader = Shader("vertexCode.txt", "fragmentCode.txt");

	unsigned int VAO;
	glGenVertexArrays(1, &VAO);
	glBindVertexArray(VAO);

	unsigned int VBO;
	glGenBuffers(1, &VBO);
	glBindBuffer(GL_ARRAY_BUFFER, VBO);
	glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

	unsigned int EBO;
	glGenBuffers(1, &EBO);
	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
	glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);

	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0);
	glEnableVertexAttribArray(0);

	glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)(3 * sizeof(float)));
	glEnableVertexAttribArray(1);

	while (!glfwWindowShouldClose(window))
	{
		HandleInput(window);
		glClearColor(0.5f, 0.2f, 0.3f, 1.0f);
		glClear(GL_COLOR_BUFFER_BIT);

		testShader.UseShader();
		glBindVertexArray(VAO);
		glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);


		//glDrawArrays(GL_TRIANGLES, 0, 3);
		glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);


		glfwSwapBuffers(window);
		glfwPollEvents();
	}

	glDeleteVertexArrays(1, &VAO);
	glDeleteBuffers(1, &VBO);
	glfwTerminate();
}

Shader.cpp

#include "Shader.h"
#include <iostream>
#include <fstream>
#include <sstream>

#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <bits/stdc++.h>

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

	vertexFile.open(vertexPath);
	fragmentFile.open(fragmentPath);
	vertexFile.exceptions(std::ifstream::failbit || std::ifstream::badbit);
	fragmentFile.exceptions(std::ifstream::failbit || std::ifstream::badbit);
	
	try
	{
		if (!vertexFile.is_open() || !fragmentFile.is_open())
		{
			throw std::exception("OPEN FILE ERROR");
		}
		// 读取文件的缓冲内容到数据流中
		vertexSStream << vertexFile.rdbuf();
		fragmentSStream << fragmentFile.rdbuf();
		// 关闭文件处理器
		vertexFile.close();
		fragmentFile.close();
		// 转换数据流到string
		vertexCode = vertexSStream.str();
		fragmentCode = fragmentSStream.str();

		vertexSource = vertexCode.c_str();
		fragmentSource = fragmentCode.c_str();

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

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

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

		glDeleteShader(vertex);
		glDeleteShader(fragment);
	}
	catch (std::ifstream::failure &e)
	{
		std::cout << "ERROR::SHADER::FILE_NOT_SUCCESFULLY_READ" << std::endl;
	}
}

Shader::~Shader()
{

}

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

Shader.h

#pragma once
#include <string>
class Shader
{
public:
	// shader program id
	unsigned int ID;
	const char* vertexSource;
	const char* fragmentSource;
	Shader(const char* vertexPath, const char* fragmentPath);
	~Shader();
	void UseShader();
};

vertextCode & fragmentCode

#version 330 core
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec3 aColor;

out vec4 ourColor;

void main()
{
    gl_Position = vec4(aPos, 1.0);
    ourColor = vec4(aColor, 1.0);
}

--------------------------------------------------------
--------------------------------------------------------

#version 330 core
out vec4 FragColor;

in vec4 ourColor;

void main()
{
    FragColor = ourColor;
}