#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#include <time.h>
#include <dos.h>
#include <graphics.h>
#define LEN sizeof(struct rainDrop)

int rainDropNumber=60;
int downSpeed=20;
struct rainDrop *head;

struct rainCircle
{
int x;
int y;
int r;
int curR;
int rainCircleStep;
};

struct rainDrop
{
int startX;
int startY;
int endY;
int curX;
int curY;
int rainColor;
int rainLineStep;
int rainLineLength;
int status;
struct rainCircle water;
struct rainDrop *next;
};

void initgraphics(void)
{
int gmode,gdriver;
gdriver=DETECT;
initgraph(&gdriver,&gmode,"");
}

struct rainDrop *creatDrop(void)
{
struct rainDrop *p;
p=(struct rainDrop *)malloc(LEN);
p->startX=rand()%640;
p->startY=rand()%430;
p->endY=430+rand()%50;
p->curX=p->startX;
p->curY=p->startY;
p->rainLineStep=8;
p->rainColor=rand()%15+1;
p->rainLineLength=rand()%10+10;
p->status=0;
p->water.x=p->startX;
p->water.y=p->endY;
p->water.r=rand()%40;
p->water.curR=rand()%2;
p->water.rainCircleStep=rand()%2+1;
p->next=NULL;
return(p);
}

void recreatDrop(struct rainDrop *p)
{
p->startX=rand()%640;
p->startY=rand()%430;
p->endY=430+rand()%50;
p->curX=p->startX;
p->curY=p->startY;
p->rainLineStep=8;
p->rainColor=rand()%15+1;
p->rainLineLength=rand()%10+10;
p->status=0;
p->water.x=p->startX;
p->water.y=p->endY;
p->water.r=rand()%40;
p->water.curR=rand()%2;
p->water.rainCircleStep=rand()%2+1;
}

void creatRain(void)
{
struct rainDrop *p1,*p2;
int i;
p1=p2=creatDrop();
head=p1;
for(i=0;i<rainDropNumber;i++)
{
p2=creatDrop();
p1->next=p2;
p1=p2;
}
}

void updateRainLineData(struct rainDrop *p)
{
if(p->rainLineStep%5==0)
p->rainLineStep++;
p->curY+=p->rainLineStep;
p->startY=p->curY-p->rainLineLength;
}

void drawRainLine(struct rainDrop *p)
{
setcolor(p->rainColor);
line(p->startX,p->startY,p->curX,p->curY);
}

void clearRainLine(struct rainDrop *p)
{
setcolor(BLACK);
line(p->startX,p->startY,p->curX,p->curY);
}

void rainDropDown(struct rainDrop *p)
{
if(p->curY>=p->endY)
{
clearRainLine(p);
p->status=1;
}
else
{
clearRainLine(p);
updateRainLineData(p);
drawRainLine(p);
}
}

void updateRainCircleData(struct rainDrop *p)
{
p->water.curR+=p->water.rainCircleStep;
}

void drawRainCircle(struct rainDrop *p)
{
setcolor(p->rainColor);
circle(p->water.x,p->water.y,p->water.curR);
}

void clearRainCircle(struct rainDrop *p)
{
setcolor(BLACK);
circle(p->water.x,p->water.y,p->water.curR);
}

void fallToWater(struct rainDrop *p)
{
if(p->water.curR>=p->water.r)
{
clearRainCircle(p);
recreatDrop(p);
}
else
{
clearRainCircle(p);
updateRainCircleData(p);
drawRainCircle(p);
}
}

void rain(void)
{
struct rainDrop *p;
p=head;
while(!kbhit())
{
if(p==NULL)
p=head;
else
{
if(p->status==0)
rainDropDown(p);
else
fallToWater(p);
}
delay(downSpeed);
p=p->next;
}
}

void clearAll(void)
{
struct rainDrop *p,*pf;
p=head;
while(p!=NULL)
{
pf=p;
p=p->next;
free(pf);
}
closegraph();
}

main()
{
printf("Input rainDrop Number:");
scanf("%d",&rainDropNumber);
printf("Input down speed:");
scanf("%d",&downSpeed);
randomize();
initgraphics();
creatRain();
rain();
clearAll();
}