[MUD-Dev] Quake II has gone GPL

[Vincent Archer]

According to shren:

>> This looks stupid, from a theoretical point of view, but it
>> usually works (i.e. A and B get to see a "correct" situation, in
>> which either A passes before B manage to get to the door, or A is
>> blocked by B).  This only fails if lag is major and the situation
>> borderline (they rush to the door at the same time).
 
> This is interesting; clarify further.  I'm A and I'm using a "I
> never collide with any other player" cheat.  B runs into me, B is
> not using such a cheat.  Does that mean that A is blocked by B,
> because B tells the server, "I hit A"?

No. It's exactly as you postulate: each client runs his own
collision detection and behaves according to *his* vision of the
world state.  The server does not detect any collisions, nor even
attempt to correlate collisions between mobiles. The only thing A or
B send is "I'm at X,Y,Z now, facing heading H, and moving at speed
S".

This is why, for example, server-animated mobiles do not collision
with each other or the players. A player cannot pass (unless hacked)
thru another player; MOBs routinely interpenetrate or pass thru
players with ease.

In fact, the are some circumstances where a player can lose control
of himself (charm). In these cases, the server is driving you, and
you become capable of interpenetrating anything.

Asheron's Call uses server-validated moves, on the other hand, and
not only validates your movement (which is apparent when lagging
bad, as you start running in place once you move out of the "need
validation" radius from the last validated position), but also does
collision. I've often slipped between two monsters to run away, only
to warp 1s later back into the crowd because what my client thought
as passage wasn in fact blocked.

I can attest that, even if it's the more accurate version, it *is*
annoying as hell, and you quickly learn not to trust your client at
all regarding your position.

--
	Vincent Archer			Email:	archer at frmug.org

All men are mortal.  Socrates was mortal.  Therefore, all men are Socrates.
							(Woody Allen)
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