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[Dehacked] Lower player-radius -> go through random walls

 
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[FEAR]Tobi
Dominating!


Joined: 12 Jan 2007
Location: Stuck in my mansion

PostPosted: Wed Jul 14, 2010 11:55 pm    Post subject: [Dehacked] Lower player-radius -> go through random walls Reply with quote

I decreased the player radius from 16 -> 4 and after that I noticed that I can just run through some walls into the void. It doesn't always work, but it should be quickly reproducible.

Here's a wad to show it:
http://wadhost.fathax.com/files/testdhwb.zip
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EarthQuake
Wicked Sick!


Joined: 02 Apr 2004
Location: Athens, Ohio. Dieblieber gonna getcha!

PostPosted: Thu Jul 15, 2010 12:47 am    Post subject: Reply with quote

This is part of how the Doom engine works. It's hard to explain how Doom does collision detection and movement, but think of it like this:

If I were to move in a straight line, my coordinates actually sorta "jump" along different points along that path. This is based on my radius and exactly how fast I am moving. My speed is actually how much distance I move over a set amount of time (in terms of tics). So if I'm approaching a wall, and my radius is really small, then I have a chance to move through the wall because I "jumped" along to a point beyond the wall bypassing the collision detection. From my understanding, Doom attempts to correct this using the last point I jumped to, and snaps me back if I attempt to pass through a wall. Because the radius is so small, sometimes that last point is actually inside the wall, and I'm now on the other side.

I might not have got that 100% correct, but it should be enough to explain what's going on. Basically what this amounts to is that it cannot be fixed. It's part of the game's physics and if fixing it were actually possible, it would ruin a lot of effects like the plasma bump in map01.

If you really must reduce the player radius, try a larger value.
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DoomerMrT
Dominating!


Joined: 09 Mar 2007
Location: http://destiny-server.ath.cx/forums/

PostPosted: Thu Jul 15, 2010 6:19 pm    Post subject: Reply with quote

Yeah low values like this may screw things up. Also applies for missiles, but as it has been said, this is a vanilla doom thing and shouldn't be messed with.
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[FEAR]Tobi
Dominating!


Joined: 12 Jan 2007
Location: Stuck in my mansion

PostPosted: Thu Jul 15, 2010 9:44 pm    Post subject: Reply with quote

Well ok, thanks for the info.
After hearing the complications about it I suppose that it should just stay the way it is, besides I think it could be avoided by just making a thick solid wall.
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Lyfe
Puts the 'Z' in ZDaemon


Joined: 29 May 2002

PostPosted: Thu Jul 15, 2010 11:12 pm    Post subject: Reply with quote

I have a fix for your problem: don't reduce the player radius to 4.


If that isn't suitable, then the next fix is just to make everything else 4 times bigger.
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