Some troubles with sleeping and size of collision primitives

[ledahut]

I try with version 223 and the body wake up if you set newtonmatrix.
I have the same bug when I want to use kinematic Joint on a sleeping body [It does not wake up by connecting the joint]. viewtopic.php?f=12&t=6122

Just wait for the next version, or work on an older one for the moment.

[Stucuk]

Is any force being applied to the body or Joint(If the object is on the ground then gravity isn't counted by this question as its not enough to move the object)? If not then it will just goto sleep anyway.

[ledahut]

Try http://le.dahut.free.fr/simple.exe
Yellow=awake, orange= sleep.
Only one ground and one dynamic body.
Mouse1 to pick, mouse2 to change camera orientation, MouseWheel to move camera.
Autofreeze=1

If you try to pick the body after it start sleeping mode then It will not work with newton 2.24. (Just try to copy dll in the same directory as exe).


RQ: Move the camera to get the sleeping state [color change on renderscreen].
(I have another problem, the body wont sleep after picking, if It has never before. But this is maybe my code).

[Julio Jerez]

Is that tes usingh later 2.24?
can you post it in the Bug Track forum?

[ledahut]

That test use 2.16 to 2.24 [That depends of the dll program load.]
Sleep work good until 2.23 [included] , I think it's not a joint's bug because FadeToBlack has the same bug when he teleports a sleeping body with NewtonBodySetMatrix.

can you post it in the Bug Track forum?

The new subForum? Or the bugtracker Thread?

[Julio Jerez]

the new subforum please.
Later Delfi will move what is in the BugTraker to the new sub forum.

[ledahut]

Only administrators can post topics or move them there, ordinary users cannot make topics there but they can reply to topics which are moved there.

[Julio Jerez]

Delfi, how that works?

[FadeToBlack]

and another problem:
why bodies get some additional impulse when one body penetrate in other? i set elasticity to 0.0 and softness to 0.1, but sometimes bodies jump when collide.

[Julio Jerez]

maybe elasticity to 0.1 and softness to 0.0

[FadeToBlack]

I`ve tested again and again to ensure that softness woks wrong.
it seems the elasticity is parameter of body restitution (like it named in other physical engines)
it seems the softness is speed of pulling bodies in contact normal direction. it is only for visual effect, not for physics simulation and it should`nt cause impulse changing.
where is mistake in my thoughts?

[Julio Jerez]

I`ve tested again and again to ensure that softness woks wrong.

softeness is not wrong.

it seems the elasticity is parameter of body restitution (like it named in other physical engines)

yes elasticity is what some people call restitution, but I do not call it elasticity because any one else call Elasticity too,
I call it because in clasical mechanic that is the name of the properties a collision between Plastic to Elastic bodies.
It could be that other physics are calling Elasticity because they saw in Newton First. The defintion comes a collison being clasifyed somewhere from Plastic to Elastic.

it seems the softness is speed of pulling bodies in contact normal direction. it is only for visual effect, not for physics simulation and it should`nt cause impulse changing.
where is mistake in my thoughts?

yes this is correct, but softeness is a penalty acceleration that is added to the contact point if they penetrate.
it is not propotional to the penetration, instead the penetration is use as a switch to decide if using the softhness or not,

In Newton this parameter is not visual, is is in fact translate to an impulsive force add to the contact point, and it is one of the reason collision can go bad if you set that value to anything too high.
the parameter have not physical explanation other that recover bodies from penetation.
so the physics of it are umpredicatble since I do not have any physcial/mathematical expresion to add it to the engine.
like I said, set it to zero, the engine do recover from penetration graciously by separating the at a constant speed when they penetrate.

[FadeToBlack]

ok, now its clear. thank you for good explanation!

[FadeToBlack]

i have problems with sleeping again. i want to make animated body, the body which follows some path and can interact physically with other bodies. for example, it is look like an elevator or other mechanism with nontrivial movement/rotation. i've tried to do it many ways, like creating bodies with large mass and adding them some velocities in direction to the target position. this ideas failed, because i get lag between target position & real body position. i've tried to calculate velocity like velocity = (new_pos - old_pos) / dt or velocity = (new_pos - old_pos) * 100.0f, the same for omega. in one perfect moment i've found some interesting thing - it is possible to apply velocities to static bodies (with mass=0.0f) and it can interact with other bodies (body is still, but interact like moving). i test it feature, and it works fine except the one thing: when static body moves it can't awake dynamic bodies and penetrate to all sleeping bodies. if in contact moment body don't sleep, it's work excellent. Question is: how can i implement my feature (path following) another way? or how can i awake bodies that becomes contacted with my static(mass=0), but moving(!!!), body?

[Julio Jerez]

are you using newton 1.53?