particles mass

#1

Hi,
someone can help me to understand how to get right mass properties on box#2 meshes?
tnx.

#2

Without wind resistance all objects fall at the same speed.

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

#3

oh my…this is the physx power?!
I’ve downloaded your Max2009_Box2_GlueFractureEX.zip…you’re telling me that the mass operator is useless without wind?

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.

#4

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.

#5

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.

#6

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?

#7

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.

#8

There is a Strength by mass checkbox, when it is On, RayFire takes into account object’s mass to apply some force.

#9

hi mir and thanks for your reply.
I did a test…3 spheres with different mass and a gravity force added, streght_by_mass checked.
after various setting, all 3 spheres impact ever at same time.
is possible to have a simple scene to study it?
thanks.

#10

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