powder.c

int try_move(int i, int x, int y, int nx, int ny)
{
        unsigned r;


        if(nx<0 || ny<0 || nx>=XRES || ny>=YRES)
                return 0;
        if(x==nx && y==ny)
                return 1;
        r = pmap[ny][nx];
        if(r && (r>>8)<NPART)
                r = (r&~0xFF) | parts[r>>8].type;

        if(parts[i].type==PT_PHOT&&((r&0xFF)==PT_GLAS||(r&0xFF)==PT_PHOT||(r&0xFF)==PT_CLNE||((r&0xFF)==PT_LCRY&&parts[r>>8].life > 5)))
        {
                return 1;
        }

        if((r&0xFF)==PT_VOID)
        {
                parts[i].type=PT_NONE;
                return 0;
        }