C 绘图

    #include "graphics.h"
    #define LEFT 0
    #define TOP 0
    #define RIGHT 639
    #define BOTTOM 479
    #define LINES 400
    #define MAXCOLOR 15
    int main()
    {
    int driver,mode,error;
    int x1,y1;
    int x2,y2;
    int dx1,dy1,dx2,dy2,i=1;
    int count=0;
    int color=0;
    driver=VGA;
    mode=VGAHI;
    initgraph(&driver,&mode,"");
    x1=x2=y1=y2=10;
    dx1=dy1=2;
    dx2=dy2=3;
    while(!kbhit())
    {
        line(x1,y1,x2,y2);
        x1+=dx1;y1+=dy1;
        x2+=dx2;y2+dy2;
        if(x1<=LEFT||x1>=RIGHT)