计算机图形学之组合图形的绘制（主要是渐变的实现）

设计动物角色，代码如下：

#include<GL/glut.h>
#include<stdio.h>
#include<math.h>
#define PI 3.1416   
//矩形绘制
void glRect(int leftX,int leftY,int rightX,int rightY,int MODE)
{
       
glBegin(MODE);    
glVertex2d(leftX,leftY);    
glVertex2d(rightX,leftY);    
glVertex2d(rightX,rightY);    
glVertex2d(leftX,rightY);    
glEnd();
}
//画弧线
void glArc(double x,double y,double start_angle,double end_angle,double radius,int MODE){
          
glBegin(MODE);    
double delta_angle=PI/180;    
for (double i=start_angle;i<=end_angle;i+=delta_angle)    
{
           
double vx=x+radius * cos(i);        
double vy=y+radius * sin(i);        
glVertex2d(vx,vy);    
}    
glEnd();
}
//画圆
void glCircle(double x, double y, double radius,int MODE)  
{
         
//画全圆    
glArc(x,y,0,2*PI,radius,MODE);  
}  
//画三角形
void glTri(int x1,int y1,int x2,int y2,int x3,int y3,int MODE){
       
glBegin(MODE);    
glVertex2d(x1,y1);    
glVertex2d(x2,y2);    
glVertex2d(x3,y3);    
glEnd();
}
//画四边形
void glFour(int x1,int y1,int x2,int y2,int x3,int y3,int x4,int y4,int MODE){
       
glBegin(MODE);    
glVertex2d(x1,y1);    
glVertex2d(x2,y2);    
glVertex2d(x3,y3);    
glVertex2d(x4,y4);    
glEnd();
}
//画五边形v
oid glFive(int x1,int y1,int x2,int y2,int x3,int y3,int x4,int y4,int x5,int y5,int MODE){
       
glBegin(MODE);    
glVertex2d(x1,y1);    
glVertex2d(x2,y2);    
glVertex2d(x3,y3);    
glVertex2d(x4,y4);    
glVertex2d(x5,y5);    
glEnd();
}
//画线，传入两点坐标
void glLine(int x1,int y1,int x2,int y2,int MODE){
       
//画封闭线    
glBegin(MODE);    
glVertex2d(x1,y1);    
glVertex2d(x2,y2);    
glEnd();
} 
//绘制圆角矩形
void glRoundRec