Doomsday Engine

Class changing weapon bindings

• http://sourceforge.net/p/deng/bugs/_discuss/thread/83384292/a95e/attachment/hexen_class_weapon_change_binds.txt

When a player class change occurs, the player is spawned again at the same location resulting in a new mobj. Problem is, there could be pointers to the old mobj all over the place, for sector sound origins and indeed enemy pursuit targets. Even though the old mobj is "removed", it may not actually be free'd, instead being moved to list of used mobjs ready for reuse, however, it might be a while before that happens and in the mean time, pointers to it are still valid. Thats why attacking the empty spot where you were when you changed class still causes you damage because there is copy of yourself there.

Why are we calling P_SpawnPlayer in this instance? Do we truely want a new mobj at this time? If so then obviously we have quite a bit of bookkeeping that is missing that needs adding.

Or by calling P_SpawnPlayer are we just trying to return the player to the state they would be in had they spawned at the current player position and of the target class? If so then it would be a good idea to split the default player state setup out of P_SpawnPlayer and into a new routine which can be called by both P_SpawnPlayer and P_PlayerChangeClass.

Personally, I favour doing the later as its simpler all round.

After further investigation, doing this the proposed "easy" way would not actually be possible without first addressing a fundamental design issue:

In Hexen, each player class has mobj type specifically for that class (fighter = MT_PLAYER_FIGHTER, cleric = MT_PLAYER_CLERIC, etc...).

So that means that we need either need to change the mobj type dynamically (might be tricky? what is tied to this?) or we need to revise how we interpret the mobj types for jHexen, spawning all players as MT_PLAYER and then picking the Mobj type definition according to a mobj_t->type AND mobj_t->class.

I'm raising the priority of this to a more appropriate level because it is a real stability issue. Particularly in multiplayer where there is the very real possibility of crashing the server merely by playing the game in the intended manner. See my comment on 2009-03-12 at 02:08 PDT for more details.

Note that since commit d407b76c, Hexen's player class changes only occur when players respawn.

In deathmatch yes, however when the player morphs to a pig in coop the same dangling pointers are left behind as in singleplayer.

- labels: jHexen Gameplay --> Hexen