CGTalk - Explosion FX + dynamics

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brammelo

03-22-2003, 10:33 PM

Hi Guys,

Imagine an devided cube subjected to the FX explosion deformer. Works perfect for simulating explosions, but the debris should collide with a floor. I tried combining it with dynamics, but I ran into two problems:

(a) the explosion deformer is a child of the cube, and drops down due to gravity.
(b) the pieces of debris are not calculated as separate pieces, but are calculated as a group. kinda of strange to see the whole group bounce up again when the first piece hits the ground.

The question is pretty obious: how should it solve this? Use TP? Or are there other objects in the Dynamics module that can be used to simulate an explosion?

I don't know much about TP or dynamics, so my appologies if this is a textbook situation. If it is textbook, just let me know, and I'll dive into the manuals.

thanks in advance,
BaRa

Per-Anders

03-23-2003, 12:25 AM

take a look at my "teardrop" example using TP on my site

http://www.peranders.com/c4d8/

this should help. the node that gives you pretty much the same results as explosionfx is pfragment.

brammelo

03-23-2003, 11:21 AM

Hi Per,

Thanks for replying. I surely will take a look at your solution, but first I'm gonna try something else, using dynamics. Not sure it will work, but this is what I need to test:

- subdivide and/or knife volume, and split parts into different polygons. Each polygon (with thickness) is considered a rigid body.
- animate the gravity - which means having it at zero for a while, so nothing moves.
- use an invisible rigid body sphere at the inside of the to be exploded volume, and animate its radius, so it pushes the fragments of the volume aside.

I'll let you know if it worked.

Thanks a lot for the feedback :-)
BaRa

handige_harrie

03-23-2003, 11:33 AM

Your solution sounds good brammelo, I had a similar thing in mind, but the problem is in keeping the object nicely fit together before exploding, I think you cannot achieve this when activating dynamics. So you should only be activating the dynamics solver at the point of explosion. This means that if you have a falling object like mdme_sadie's teardrop you would have to animate the falling motion by hand.

Unfortunately dynamics is hell (imo) involving static objects (that will move later on, but have to remain at rest in the beginning). Objects do not remain at rest and tend to slide through eachother. High solver settings can slow down this but never eliminate it.

Maybe someone has a nice workaround for this problem :hmm: :)

brammelo

03-23-2003, 05:43 PM

Dag Peter,

By keeping the gravity at a zero value for a time, the objects remain in place. So that part seems to work. I have other problems though, as you expected:

- intersection of parts once the dynamics kick in.
- blowing up the thing. I used a sphere of which I animated the scale, but this didn't do much. So I tried it with an (animated) wind object, but it's hell to tweak.

Cheers,
BaRa

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