#include "snap.h"

IMPORT struct RastPort rp;

Point OldFrame[9];
Point NewFrame[9];
LONG OFType = 0;
UWORD Ptrn;

STATIC VOID MultiDraw(rp, num, xy)
struct RastPort *rp;
LONG num;
Point *xy;
{
    REGISTER LONG i = 0;
    REGISTER Point *coord = xy;
    while (i<num) {
        Move(rp, (LONG)coord->x, (LONG)coord->y);
        coord++;
        Draw(rp, (LONG)coord->x, (LONG)coord->y);
        i++;
    }
}

VOID crawl_frame(dir)
LONG dir;
{
    REGISTER UWORD temp = Ptrn;
    if (dir) {
        Ptrn = ((Ptrn<<1) & 0xfffe) | ((Ptrn & 0x8000)>>15);
    } else {
        Ptrn = ((Ptrn>>1) & 0x7fff) | ((Ptrn & 1)<<15);
    }        
    temp ^= Ptrn;
    SetDrPt(&rp, temp);
    MultiDraw(&rp, OFType, &OldFrame[0]);
    SetDrPt(&rp, Ptrn);
}

VOID erase_frame()
{
    if (OFType) {
        MultiDraw(&rp, OFType, &OldFrame[0]);
        OFType = 0;
    }
}

VOID draw_frame(ft)
LONG ft;
{
    REGISTER LONG i;
      /* Remove old frame */
    WaitTOF();
    erase_frame();
      /* Draw the new frame */
    MultiDraw(&rp, ft, &NewFrame[0]);
      /* save the frame for erasing later */
    for (i=0; i<=ft; i++) {
        OldFrame[i].x = NewFrame[i].x;
        OldFrame[i].y = NewFrame[i].y;
    }
    OFType = ft;
}