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3 questions

Apr 30, 2009 at 6:37 AM
1. Can I not dynamically set the friction coefficient? I set it, and i confirm it was set but the friction is still acting like its 0.
2. When i try to create an elipse body and geom i give it the normal height and width but the body and geom are way bigger than what i defined, and when i change the collision grid it changes its size.
Is there a specific size i should specify? or is their any special way to set parameters for eliptical bodies im missing?
3. The reason why i wanna use an elipse body is because i wanna be able to tell where on the geom it collides, whether its top bottom left or right, and from what ive heard its possible with an elipse.
Is there any other way to check collisions in a similar way?

I am having problems controlling the jumping when it comes to walls and offset bodies
Thanks in advance, and if anybody has any random ideas on controlling jumping please chime in.
Apr 30, 2009 at 2:57 PM
1. The default friction type in FP is FrictionType.Average. This means that the average friction of the two geometries is the friction applied between them. Try changing the friction of both the geometries colliding.

2. What version is this in: 2.0.1 or the source control builds? I remember changing ellipses to use radius instead of width and height. Can't remember when... It should be fixed in the source control builds, I would appreciate it if you can confirm this.

3. Ellipse bodies does not know anything about collisions. It only knows about force and its moment of inertia. Ellipse geometries on the other hand, know about geometries. Anyway, the physics engine does not really know what is up and what is down. You have to come up with a solution to find out where the geometries are in relation to each other.
You could do a check when the geometries collide. If the Y value of the other geometry is lower than the one it's colliding with, then it's higher up - so on and so forth.
This can be done with all the geometries, not only ellipses.

4. As for the jumping, apply an impulse to the character and he should jump. You have to specify your problems for further help.
Apr 30, 2009 at 7:06 PM
Thank you,
I will check the friction change when i get home, currently i am able to set the friction level on 1 geometry and it will apply it correctly,
but when i try to change eit in-game it causes problems, i will apply frictions to other geometries though to see if it fixes itself.

I am using a build from april 20th so its not completely up to date i will download the latest check in.

I know elipse bodies dont know i said i made elipse bodies and geomtries, i had thought that an elipse would calculate vertices and i could check a specific vertices
There was another thread where someone said they did it
It was the one with the kid doing a platformer for school and he was talking about restitution co-efficient for balls in his game, nvm

But I know how to apply impulse forces etc, i know how to make the character jump
My problem is making sure an impulse is only applied if they are on the ground, i check against the geometries in the simulator to see if its colliding and if it is and its not falling or jumping it can jump.
My problem was making so that it was not able to jump off the sides of geomtries.
Sorry i realize i wasnt being as specific as i shouldve been.

I will add a condition about the Y position of the entire geometry but it seems like that is bound to be buggy,
o well its worth a try.