VS2012下基于Glut OpenGL GL_TRIANGLES示例程序：

在VS2012下使用glut GL_TRIANGLES绘制三角形示例程序，绘制的是两个三角形，效果如下图所示，按PC的UP,DOWN,LEFT,RIGHT按键可以从不同的角度查看该图形。GL_TRIANGLES连续点生成三角形的规则如下图所示：

源代码如下：

// GlutTriangleDemo.cpp : 定义控制台应用程序的入口点。//#include "stdafx.h"#include <gl/glut.h>#include <math.h>//圆周率宏#define GL_PI 3.1415f//获取屏幕的宽度GLint SCREEN_WIDTH=0;GLint SCREEN_HEIGHT=0;//设置程序的窗口大小GLint windowWidth=400;GLint windowHeight=300;//绕x轴旋转角度GLfloat xRotAngle=0.0f;//绕y轴旋转角度GLfloat yRotAngle=0.0f;//显示回调函数void renderScreen(void){    GLfloat x,y,z,angle;    //把整个窗口清理为当前清理颜色：黑色    glClear(GL_COLOR_BUFFER_BIT);    //将当前Matrix状态入栈    glPushMatrix();    //坐标系绕x轴旋转xRotAngle    glRotatef(xRotAngle,1.0f,0.0f,0.0f);    //坐标系绕y轴旋转yRotAngle    glRotatef(yRotAngle,0.0f,1.0f,0.0f);//进行平滑处理　glEnable(GL_LINE_SMOOTH);glHint(GL_LINE_SMOOTH,GL_NICEST);//设置绘画颜色为白色    glColor3f(1.0f,1.0f,1.0f);//绘制坐标系glBegin(GL_LINES);glVertex3f(-80.0f,0.0f,0.0f);glVertex3f(80.0f,0.0f,0.0f);glVertex3f(0.0f,-80.0f,0.0f);glVertex3f(0.0f,80.0f,0.0f);glVertex3f(0.0f,0.0f,-80.0f);glVertex3f(0.0f,0.0f,80.0f);glEnd();glPushMatrix();glTranslatef(80.0f,0.0f,0.0f);glRotatef(90.0f,0.0f,1.0f,0.0f);glutWireCone(3,6,10,10);glPopMatrix();glPushMatrix();glTranslatef(0.0f,80.0f,0.0f);glRotatef(-90.0f,1.0f,0.0f,0.0f);glutWireCone(3,6,10,10);glPopMatrix();glPushMatrix();glTranslatef(0.0f,0.0f,80.0f);glRotatef(90.0f,0.0f,0.0f,1.0f);glutWireCone(3,6,10,10);glPopMatrix();    //设置绘画颜色为绿色    glColor3f(0.0f,1.0f,0.0f);//开始绘制两个三角形glBegin(GL_TRIANGLES);glVertex3f(0.0f,0.0f,0.0f);glVertex3f(50.0f,0.0f,0.0f);glVertex3f(25.0f,25.0f,0.0f);glVertex3f(-25.0f,0.0f,0.0f);glVertex3f(-75.0f,0.0f,0.0f);glVertex3f(-50.0f,25.0f,0.0f);    //结束绘三角形    glEnd();    //恢复压入栈的Matrix    glPopMatrix();    //交换两个缓冲区的指针    glutSwapBuffers();}//设置Redering State void setupRederingState(void){    //设置清理颜色为黑色    glClearColor(0.0f,0.0,0.0,1.0f);    //设置绘画颜色为绿色    glColor3f(0.0f,1.0f,0.0f);}//窗口大小变化回调函数void changSize(GLint w,GLint h){    //横宽比率    GLfloat ratio;    //设置坐标系为x(-100.0f,100.0f)、y(-100.0f,100.0f)、z(-100.0f,100.0f)    GLfloat coordinatesize=100.0f;    //窗口宽高为零直接返回    if((w==0)||(h==0))        return;    //设置视口和窗口大小一致    glViewport(0,0,w,h);    //对投影矩阵应用随后的矩阵操作    glMatrixMode(GL_PROJECTION);    //重置当前指定的矩阵为单位矩阵　    glLoadIdentity();    ratio=(GLfloat)w/(GLfloat)h;    //正交投影    if(w<h)        glOrtho(-coordinatesize,coordinatesize,-coordinatesize/ratio,coordinatesize/ratio,-coordinatesize,coordinatesize);    else        glOrtho(-coordinatesize*ratio,coordinatesize*ratio,-coordinatesize,coordinatesize,-coordinatesize,coordinatesize);    //对模型视图矩阵堆栈应用随后的矩阵操作    glMatrixMode(GL_MODELVIEW);    //重置当前指定的矩阵为单位矩阵　    glLoadIdentity();}//按键输入处理回调函数void specialKey(int key,int x,int y){    if(key==GLUT_KEY_UP){        xRotAngle-=5.0f;    }    else if(key==GLUT_KEY_DOWN){        xRotAngle+=5.0f;    }    else if(key==GLUT_KEY_LEFT){        yRotAngle-=5.0f;    }    else if(key==GLUT_KEY_RIGHT){        yRotAngle+=5.0f;    }    //重新绘制    glutPostRedisplay();}int main(int argc, char* argv[]){    //初始化glut     glutInit(&argc,argv);    //使用双缓冲区模式    glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGBA|GLUT_DEPTH);    //获取系统的宽像素    SCREEN_WIDTH=glutGet(GLUT_SCREEN_WIDTH);    //获取系统的高像素    SCREEN_HEIGHT=glutGet(GLUT_SCREEN_HEIGHT);//创建窗口，窗口名字为OpenGL TriAngle Demo    glutCreateWindow("OpenGL TriAngle Demo");    //设置窗口大小    glutReshapeWindow(windowWidth,windowHeight);    //窗口居中显示    glutPositionWindow((SCREEN_WIDTH-windowWidth)/2,(SCREEN_HEIGHT-windowHeight)/2);    //窗口大小变化时的处理函数    glutReshapeFunc(changSize);    //设置显示回调函数     glutDisplayFunc(renderScreen);    //设置按键输入处理回调函数    glutSpecialFunc(specialKey);    //设置全局渲染参数    setupRederingState();    glutMainLoop();    return 0;}