dynamic rigid bodies looks so weight lighted

Visual, Game & Mobile Development Physics Modeling
#1

hello every body

would you please help me with this problem

i have create a rigid dynamic body (simple box shape)

and set it’s mass to 1000kg and updated it’s interia… but it doesn’t look so heavy and acts like a small 0.0001kg box.

what should i do???

#2

Hello,

Could you please provide some more details? Posting the code you use to instantiate the rigid body and a pvd dump would be most helpful.

Thanks,

Gordon

#3

hi

justing creating a simple dynamic box as sdk says

dynamicRigidBody* box = createNew…;
setMass&UpdateInteria (100);

that is it.

i want it to be 1000kg but it’s like 0.001kg

#4

Hi,

Some more details would be most helpful in figuring out what is not working as you expect. In what way exactly does it behave like a 0.001kg box?

Thanks,

Gordon

#5

Hi Gordon

I want to create a very heavy object. for example part of building that is falling.
when i want to create it, i set mass and update interia with number of 1000 (i take 1000 as 1000kg)

now i have another object (like a ball) and i set it’s mass & update interia with 1 (i assume 1 is 1kg)

after creating them and adding them to the scene when i run the simulation (they both fall from a height). i expect the building part to fall faster and bounce very less. but it behaves like the ball

Please help.

Thanks

#6

Hi,

In a vacuum a 1kg object and a 1000kg ball will accelerate under gravity at exactly the same rate. If they have the same coefficient of restitution then they will bounce with the same velocity as well. What you are seeing is physically correct.

If you want the ball to fall slower you will need to increase its damping rate.

PxRigidDynamic* myBall;
float ballDampingRate;
myBall->setLinearDamping(ballDampingRate);

The default damping rate is 0.05 so you will need to experiment with ballDampingRate > 0.05 until it provides the behaviour you want to see. It might be useful to set the angular damping rate to a higher value than the default too. For a more complete model you could also apply forces to mimic aerodynamic drag working against the ball.

To make the building part bounce less you will need to decrease the coefficient of restitution. It is probably a good idea to set the restitution to zero. To do this you need to create another PxMaterial with zero restitution and then apply that material to the ball’s PxShape on construction.

Thanks,

Gordon