试一下 moving ball

\*******'w'加速,'s'减速,'a','d'转向************\

#include <bios.h>
#include <math.h>
#include <graphics.h>
#include <stdio.h>
#include <time.h>
#include <dos.h>
#define PI 3.14159265
#define r 15
#define c(c) setfillstyle(1,c)

main()
{int x=320,y=240,x0=320,y0=240;float v=0,t=0,a=0;
 char k='0';
 int gdriver=DETECT,gmode;
  initgraph(&gdriver,&gmode,"c:\\tc2\\bgi");

 setcolor(15);
setwritemode(XOR_PUT);

while(k!='q')
 {while(bioskey(1)==0)
   {printf("t=%f,v=%f,a=%f(%d,%d)\r",t,v,a,x,y);
   if(x<=0||x>=639)a=PI-a;if(y<=0||y>=479)a=-a;
   x=v*cos(a)*t+x;y=v*sin(a)*t+y;
    line(x0,y0,x,y);
    circle(x,y,5);
    delay(5000);
    circle(x,y,5);
      x0=x;y0=y;
      t+=0.01;
      }
   k=bioskey(0);
switch(k)
  {case 'a': a-=0.1;break;
   case 'd': a+=0.1;break;
   case 's': v-=0.1;break;
   case 'w': v+=0.1;break;
  }
}
}