在VS2012下使用glut GL_TRIANGLE_STRIP绘制三角形示例程序,绘制的是多个三角形,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_TRIANGLE_STRIP连续点生成三角形的规则如下图所示:
源代码如下所示:
// GlutTriangleStripDemo.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_POINT_SMOOTH);
glHint(GL_POINT_SMOOTH,GL_NICEST);
glEnable(GL_LINE_SMOOTH);
glHint(GL_LINE_SMOOTH,GL_NICEST);
//使用白色绘制坐标系
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();
//坐标系平移到(-50.0f,0.0f,00.0f)
glPushMatrix();
glTranslatef(-50.0f,0.0f,00.0f);
//白色绘制五个顶点
glColor3f(1.0f,1.0f,1.0f);
glPointSize(5.0f);
glBegin(GL_POINTS);
glVertex3f(0.0f,0.0f,0.0f);
glVertex3f(25.0f,25.0f,0.0f);
glVertex3f(0.0f,50.0f,0.0f);
glVertex3f(-25.0f,25.0f,0.0f);
glVertex3f(-25.0f,0.0f,0.0f);
glEnd();
//GL_FLAT使用单色模式填充三角形
//GL_SMOOTH使用颜色平滑变换模式填充三角形
glShadeModel(GL_FLAT);
//使用GL_TRIANGLE_STRIP绘制三角形
glBegin(GL_TRIANGLE_STRIP);
//使用红色绘制第一个三角形
glColor3f(1.0f,0.0f,0.0f);
glVertex3f(0.0f,0.0f,0.0f);
glVertex3f(25.0f,25.0f,0.0f);
glVertex3f(0.0f,50.0f,0.0f);
//使用绿色绘制第二个三角形
glColor3f(0.0f,1.0f,0.0f);
glVertex3f(-25.0f,25.0f,0.0f);
//使用蓝色绘制第三个三角形
glColor3f(0.0f,0.0f,1.0f);
glVertex3f(-25.0f,0.0f,0.0f);
//结束GL_TRIANGLE_STRIP绘制三角形
glEnd();
glPopMatrix();
//坐标系平移到(50.0f,0.0f,00.0f)
glPushMatrix();
glTranslatef(50.0f,0.0f,00.0f);
//白色绘制五个顶点
glColor3f(1.0f,1.0f,1.0f);
glPointSize(5.0f);
glBegin(GL_POINTS);
glVertex3f(0.0f,0.0f,0.0f);
glVertex3f(25.0f,25.0f,0.0f);
glVertex3f(0.0f,50.0f,0.0f);
glVertex3f(-25.0f,25.0f,0.0f);
glVertex3f(-25.0f,0.0f,0.0f);
glEnd();
//GL_FLAT使用单色模式填充三角形
//GL_SMOOTH使用颜色平滑变换模式填充三角形
glShadeModel(GL_SMOOTH);
//使用GL_TRIANGLE_STRIP绘制三角形
glBegin(GL_TRIANGLE_STRIP);
//使用红色绘制第一个三角形
glColor3f(1.0f,0.0f,0.0f);
glVertex3f(0.0f,0.0f,0.0f);
glVertex3f(25.0f,25.0f,0.0f);
glVertex3f(0.0f,50.0f,0.0f);
//使用绿色绘制第二个三角形
glColor3f(0.0f,1.0f,0.0f);
glVertex3f(-25.0f,25.0f,0.0f);
//使用蓝色绘制第三个三角形
glColor3f(0.0f,0.0f,1.0f);
glVertex3f(-25.0f,0.0f,0.0f);
//结束GL_TRIANGLE_STRIP绘制三角形
glEnd();
glPopMatrix();
//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 TriAngleStrip Demo
glutCreateWindow("OpenGL TriAngleStrip 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;
}