# q3 collision issues

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I got the collision working using the bsp collision article, the problem now is that i cant slide up stairs( i can slide walls fine) using any of the methods they mention. How would i go about implementing possibly a ellipsoid response to it or altering the code. Thanks [Edited by - rgirard413 on December 18, 2005 10:07:09 PM]

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This is quite a problem and the people at ID solved it by having 2 Collision Boxes a MAJOR and a MINOR collision box. The Minor was 10% smaller in all dimensions and absolute collision only occured with the minor box.

If collision occured with the major box it was moved (by applying acceleration) into the direction required to solve the problem.

Another thing u could try is to check infront of the player all the time and if you detect a stair you simple lift him into the air by the needed height, this is how ID did the stairs in Quake2.

The last solution would be to go into the maps and create a new Collision plane which is just above the stairs and you will slide nicely up it, however this makes for unrealistic decent.

__
|
|___
| B R*
|____
| R

if the players foot is at R (and yoo detect you cant move forward) then simple attempt to move from R* to B if this is possible then you know you have met an edge of a stair, it is at this point where it gets tricky because going from R-->B might not be possible and thats why in q2 they simple place the unit at R* and moved it forward.

(Possible you want to reduce the players velocity due to the fact that he needs to go uphill)

In Quake3 R would be the Major Bounding Box and R* The minor, as the player moves forward the 2 Planes (1 Verticle 1 horizontal) will apply a force to R the major bounding box sending him upwards and opposing his force making a realistic effect.

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