Add lhypot to util.c

[Joris]

I think I have about 6-8 modules that use this function. It would be very useful to add it to util.c

{{{ #!C static long lhypot(register long dx, register long dy) { register unsigned long r, dd;

    dd = dx*dx+dy*dy;

    if (dx < 0) dx = -dx;
    if (dy < 0) dy = -dy;

    /* initial hypotenuse guess (from Gems) */
    r = (dx > dy) ? (dx+(dy>>1)) : (dy+(dx>>1));

    if (r == 0) return (long)r;

    /* converge 3 times */
    r = (dd/r+r)>>1;
    r = (dd/r+r)>>1;
    r = (dd/r+r)>>1;

    return (long)r;

} }}}

[Former user]

Most distances are only used for comparison, so storing the distance squared and comparing to that is better. game.c does this in IsAntiwarped(). game.c uses lhypot for a silly reason and it should be changed not to. funky/autoturrent uses it because it does rudimentary geometry/physics. Do you have uses of lhypot that don't fit those 2 cases?

[Joris]

I have not done stuff with ASSS for a while, but a quick grep tells me I used it to:

• Determine where to shoot in a destroyable staticturret module (like autoturret)
• Determine how much damage to deal to a fake player when it is hit by splash damage

int dist = lhypot(x - bx, y - by);
damage = dist * - (i32)maxdamage / radius + maxdamage;

• Determine when to trigger prox bombs (could do without hypot)
• Determine what speed a player if flying at so that I can figure out where to place a repel to give him a speed boost in the proper direction:

speed = LHypot(p->position.xspeed,  p->position.yspeed);
wpn.x = p->position.x - (p->position.xspeed / speed) * REPEL_DIST;
wpn.y = p->position.y - (p->position.yspeed / speed) * REPEL_DIST;
wpn.xspeed = -p->position.xspeed;
wpn.yspeed = -p->position.yspeed;

• Deal damage from a nuke to buildings

[Former user]

I would have to say then that lhypot doesn't belong in util.c. It's not a general programming utility. I am going to set this bug to wontfix. lhypot would be part of a hypothetical geometry or physics module, which you can file a bug for if you want.

[Joris]

okay fine with me