View Full Version : particles mass

 savat11 November 2010, 02:25 PMHi, someone can help me to understand how to get right mass properties on box#2 meshes? tnx.
JohnnyRandom
11 November 2010, 07:04 PM
Without wind resistance all objects fall at the same speed.

Where mass is most noticeable is during the collision of two objects.

savat
11 November 2010, 08:52 AM
Without wind resistance all objects fall at the same speed.

Where mass is most noticeable is during the collision of two objects.

oh my...this is the physx power?!

how to deal a "quality dynamic" scene at this point? johnny:

-disabling world gravity and including a wind force with a "gravity setting" (-Z direction)?
-or maintain gravity issue and apply a wind resistance (+Z direction) to "decelerate" small pieces over big pieces?

can you explane me a little more?
tnx again.

JohnnyRandom
11 November 2010, 07:14 PM

No, not saying that at all, mass has effect during collisions in a Default PhysX World. Mass and weight are different things, there is no "weight" in PhysX just mass AFAIK. Maybe it needs weight, since weight is the force exerted on the mass of an object to a specified gravity.

No other systems that I know of take Wind into effect either without specifying. Could use some other peoples input on this (since I am not familiar with "every" system)

What I am talking about is wind resistance. In a default PhysX World there is no wind resistance because you haven't really told it that there is any. To get wind resistance you need a PhysX Force ->Surface and either add a wind or a gravity spacewarp. It isn't perfect but I think you'll be hard pressed to find one that is.

Couple examples:
The first play with the multiplier in both events to see the effect of Mass
The second adjust the mass and/or the PhysX Force Influence values to see the different behaviour

Other than that is there something specific you are trying to do?

Anyway hope it helps a little.

savat
11 November 2010, 09:45 AM
...What I am talking about is wind resistance. In a default PhysX World there is no wind resistance because you haven't really told it that there is any. To get wind resistance you need a PhysX Force ->Surface and either add a wind or a gravity spacewarp. It isn't perfect but I think you'll be hard pressed to find one that is...

ok, in physx a feather and a rock fall down at same velocity...a resistance force who simulate air friction needs to emprove the reality of simulation.

this method however create several problem in simulations with very large and very small debris because the small part fly out and to avoid that occours an easy force setting...but this is another problem.

thanks Johnny for your time, very apreciated.

savat
12 December 2010, 03:52 PM
just a moment...
at this point same problem (same physx engine) is in ray fire indipendently from the sponge or heavy metal "material" I assign to objects.
if yes...once again I need to insert a wind/gravity space warp to obtain right gravity on masses or this trick, in RF, is useful only for right masses in collision?

JohnnyRandom
12 December 2010, 11:37 PM
Hmmm, not exactly sure how Mir is calculation mass value with RayFire. Although I would give it a test you can add spacewarps to have effect on your RayFire sim. Truth-be-told it has been a little while since I used PhysX in Rayfire.

12 December 2010, 01:38 PM
There is a Strength by mass checkbox, when it is On, RayFire takes into account object's mass to apply some force.

savat
12 December 2010, 02:55 PM
There is a Strength by mass checkbox, when it is On, RayFire takes into account object's mass to apply some force.