View Full Version : Gravity and natural movement?

06-12-2003, 01:07 PM
How do I get an object to bounce around naturally when dropped at an angle on another object, lets say a table.

I've managed to apply the gravity to make the object fall, but it just bouncec up and down in a straight line (elasticy set to 25%) until it lies still?

Do I have to apply another 'modifier' or somehow tell the object it's supposed to bounce around?

06-12-2003, 01:40 PM
I assume you mean the motion modifier, so you are in for a disappointment. There is no way of getting natural motion with just this tool since it has nothing to do with real dynamics simulation. To achieve this, you have several options:

a) Do the good old manual keyframing - since you only speak of one object, this should not be too much to ask for.

b) Read tutorials on how to do rigid body simulation with Motion Designer.

c) Find yourself some money and buy Impact! from Dynamic Realities.


06-12-2003, 05:24 PM
There is this program for 55 bucks or so. It's not the best, but it is cheap. Just make sure to read EVERYTHING that comes with it.
I found it works great, but only has some problems with Keyframed movements interacting with it's physics. I didn't spend too much time with it though...but it will let you do a little more than bounce a ball (see it's examples).


They have working demo that lets you import your LW files into it, but not export the keyframes back to LW.

This is a good step before trying to go full out for Impact!

caustic wave
07-05-2003, 03:39 AM
I have created a ground and box with a cloth on top.
I selected motion designer to collide with the box, but when it falls, it goes through the ground-MD only has 2 buttons activated for my box and cloth to collide, if I select the ground, my cloth will not collide with the box. should not MD have more then 2 buttons for object activation, i wish i was a programmer, I would re-design the MD for more then 2 object detection.

any help on this one please


07-05-2003, 09:59 AM
For an object, in the motion modifiers (M) there is a fuction called Gravity... is does simple calculations based on accelerations and there is elasticity setting for striking the ground...

Now, this maybe too simple of motion. If so, you can then output the motion file by baking it, then modifing it with Graph Editor...

Will... gravitically challenged...

07-05-2003, 10:57 AM
The problem is that you want a simulation. You can probably do this with motion designer (which can have more then two collsion objects) but its not something its specifically designed for but can be made to do with some tweaking. Its designed to do soft body (cloth) dynamics.
Impact is the closest youll get to an easy solution.
As someone mentioned, you can always do it the old fashioned way (keyframing). :)

07-05-2003, 03:54 PM
use Motion Designer or PFX!
You could easily make a hard body simulation tweaking MD (search for MD here and cgtalk) or you could use FXlinker do psuedoreal (can i coin that? :) ) simulations that may look good enough for your scene.
PFX would be easier to do, setup emitters and collisions, then FXLink your object to a particle and it will bounce off the table.

have fun!

07-05-2003, 03:54 PM
have you tried particles and object replacement ?
works for me !

07-05-2003, 09:50 PM
You could link the object to particles via FXLinker. Another option would be to make the object behave as a particle itself and react to gravity, wind and collision objects by applying fXMotion to it.

07-06-2003, 06:57 AM
splinegod, exactly my line of thinking !