Hello Triangle

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

float vertices[] = 
{
	-0.5f, -0.5f, 0.0f,
	 0.5f, -0.5f, 0.0f,
	 0.0f,  0.5f, 0.0f,
};

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

const char* vertexshaderSource = 
"#version 330 core										\n"
"layout(location = 0) in vec3 aPos;						\n"
"void main() {\n"
	"gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);} 	\n";

const char* fragmentshaderSource =
"#version 330 core\n"
"out vec4 FragColor; \n"
"void main() {\n"
"		FragColor = vec4(1.0f, 0.5f, 0.2f, 1.0f);}\n";

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

	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);

	unsigned int vertexShader = glCreateShader(GL_VERTEX_SHADER);
	glShaderSource(vertexShader, 1, &vertexshaderSource, NULL);
	glCompileShader(vertexShader);

	unsigned int fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
	glShaderSource(fragmentShader, 1, &fragmentshaderSource, NULL);
	glCompileShader(fragmentShader);

	unsigned int shaderProgram = glCreateProgram();
	glAttachShader(shaderProgram, vertexShader);
	glAttachShader(shaderProgram, fragmentShader);
	glLinkProgram(shaderProgram);

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


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

		glBindVertexArray(VAO);
		glUseProgram(shaderProgram);
		//glDrawArrays(GL_TRIANGLES, 0, 3);
		//glDrawArrays(GL_POLYGON, 0, 4);
		glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
		glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);


		glfwSwapBuffers(window);
		glfwPollEvents();
	}
	glfwTerminate();
}