int Simulation::pn_junction_sprk(int x, int y, int pt)
{
    int r = pmap[y][x];
    if ((r & 0xFF) != pt)
        return 0;
    r >>= 8;
    if (parts[r].type != pt)
        return 0;
    if (parts[r].life != 0)
        return 0;

    parts[r].ctype = pt;
    part_change_type(r,x,y,PT_SPRK);
    parts[r].life = 4;
    return 1;
}