上一篇文章中也使用了比较老的方法glBegin 和 glEnd的方法来绘制了简单的集合图元，现在使用比较新的而且更高效的方法来绘制简单的集合图元。
这种方法与以前方法的不同点在对数据的处理上，glBegin 和 glEnd是要给出数据，然后直接来进行绘制，然而新的方法是现将数据保存到显存中，然后直接一个绘制命令，，就可以直接从显卡内存中直接读取数据进行绘制，效率更高而且更方便。
#include <GL/glew.h>#include <GL/freeglut.h>#include <iostream>#include "rshader.h"using namespace std;GLuint vao;void display(){GLuint vbo;GLuint ebo;GLfloat v_position[] ={0.0f, 0.5f,0.5f, -0.5f,-0.5f, -0.5f,};GLushort indecise[] ={0, 1,1, 2,2, 0};glClear(GL_COLOR_BUFFER_BIT);glGenVertexArrays(1, &vao);glBindVertexArray(vao);glGenBuffers(1, &vbo);glBindBuffer(GL_ARRAY_BUFFER, vbo);glBufferData(GL_ARRAY_BUFFER, sizeof(v_position), v_position, GL_STATIC_DRAW);glGenBuffers(1, &ebo);glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo);glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indecise), indecise, GL_STATIC_DRAW);const char *vershader = read("vershader.txt");GLuint vshader = glCreateShader(GL_VERTEX_SHADER);glShaderSource(vshader, 1, &vershader, NULL);glCompileShader(vshader);GLint status;glGetShaderiv(vshader, GL_COMPILE_STATUS, &status);const char *fragshader = read("fragshader.txt");GLuint fshader = glCreateShader(GL_FRAGMENT_SHADER);glShaderSource(fshader, 1, &fragshader, NULL);glCompileShader(fshader);GLuint program = glCreateProgram();glAttachShader(program, vshader);glAttachShader(program, fshader);glLinkProgram(program);glUseProgram(program);GLint posAttrib = glGetAttribLocation(program, "position");glVertexAttribPointer(posAttrib, 2, GL_FLOAT, GL_FALSE, 0, 0);glEnableVertexAttribArray(posAttrib);//glDrawArrays(GL_LINE_LOOP, 0, sizeof(v_position) / sizeof(GLfloat) / 2);glDrawElements(GL_LINES, sizeof(indecise) / sizeof(GLushort), GL_UNSIGNED_SHORT, 0);glFlush();}int main(int argc, char **argv){glutInit(&argc, argv);glutInitDisplayMode(GLUT_RGBA);glutInitWindowPosition(200, 200);glutInitWindowSize(600, 600);glutCreateWindow("opengl");GLenum err = glewInit();if (err == GL_TRUE){cerr << "glew init failed!\n" << endl;exit(-1);}glutDisplayFunc(display);glutMainLoop();return 0;}
以下为简单的两个shader（只是为了说明原理，所以只有输入输出）
vershader.txt
#version 430 corein vec2 position;void main(){gl_Position = vec4(position, 0.0, 1.0);}
fragshader.txt
#version 430 coreout vec4 outColor;void main(){outColor = vec4(1.0, 1.0, 1.0, 1.0);}此处为读文件操作，将着色器源代码读入内存
#include <stdio.h>#include <stdlib.h>#include <iostream>using namespace std;const char *read(char *filename){FILE *in;in = fopen(filename, "rb");if (in == NULL){cerr << "failed to open file!" << endl;exit(-1);}fseek(in, 0, SEEK_END);unsigned int size = ftell(in);fseek(in, 0, SEEK_SET);char *data = new char[size + 1];fread(data, 1, size, in);data[size] = 0;fclose(in);return const_cast<const char *>(data);}在绘制处使用两种不同的绘制命令来进行绘制，一种是使用glDrawArrays直接读取显存中的顶点信息进行绘制；另一种是glDrawElements，这种方法需要设置GL_ELEMENT_ARRAY_BUFFER，这里存储的就是顶点绘制索引信息。
临行之前，面对太多的疑问和不解：
