Is there any way to apply Physics Behavior with a trigger?

[mikec79991839]

I have a character that has ears that I want to fall when given a trigger in the scene recording mode but haven't been able to figure it out.  The layer is independent and I have applied the "dynamic" and "collide" tag to it but as soon as I open the character in scene recording mode the ears are already gone.

Has anyone else had this experience?

Any help is appreciated.

Thank you.

[alank99101739]

When you say “fall”, do you mean fall off, or just flop down?  I don’t know how to attach a trigger to changing values (e.g. physics setting), but you can certainly arm a physics setting like gravity and Record changes in values over time. You might consider having a separate behavior so changing the gravity for the ears does not mess up anything else on the puppet as well (e.g. hair).

If the ears are pointing upwards, I believe you can have the default gravity to be negative (so it pushes up), then record a new value which is positive, pushing the ears in the opposite direction.

Another idea is to put a dragger on the ears, so you hold them up with a dragger then trim the drag to the place you want the ears to flop down, so gravity wins.

I have not tried either one - just suggestions to experiment with. But I have not seen a trigger change a property as such - just using recordings of takes and adjusting the value there.

[mikec79991839]

Those are some really good ideas.  I want the ears to just fall off... so I will try the negative gravity trick, but I like your dragger ideas as well.  Looks like most of the work will be in the recording area.

Thanks for your input. I think those may be workable solutions.

[alank99101739]

I think one of the tips and tricks videos talked about physics and particles as well. I think another option is to have the ears both as part of the puppet (with a separate transform behavior, so you can record the opacity separate to the rest of the puppet - you record a zero opacity when you want them to fall off). Then you have a separate puppet using collide etc physics behaviors (maybe with cannon to make it appear, or give it velocity etc). The separate puppet appears at the exact time you set opacity to zero, so it looks like the same puppet, but its really a separate puppet that just looks the same.

I had some trouble in this area with physics behaviors and puppets that did not start at the beginning of the scene (Problems with Physics (bouncing balls) ), so I actually had to split it into two scenes spliced at the point you want the ears to start falling. If you get a better approach working I would love to hear how you did it!  Splitting the scene is a bit of a pain to get them to exactly line up etc. It was okay for me in my case as I managed to get everything not moving at the splice point.  But using physics instead of a pure dragger gives much more natural motion paths than I have ever managed dragging to do.

[alank99101739]

Just to follow up, all the problems I reported turned out to be my problems. So no reason I know of not to try out the physicals behaviors.

So my favorite of the options is

(1) Add a transform behavior to the ears layer, so you can adjust the opacity of the ears without affecting the rest of the puppet.

(2) Record a zero opacity for the ears that time you want them to fall off.

(3) Create a separate puppet for just the ears and trim it to start at the same time the opacity goes to zero.

(4) On the second puppet add the "Dynamic" and "Collision" tags with "Start Immediately" - the ears should just fall to the ground at that time.

The only thing to watch for that is confusing is the physics behaviors cannot be scrubbed like other things - they just start and keep going even if the playhead is not moving. Sometimes you need to hit the "reset" button in the scene (the two "recycling" arrows in a circle) to reset the physics back to the start.  When you do a final render it is reliable and correct, but during editing (for speed reasons I think) the physics just play ignoring the scrubbing and editing settings.

[mikec79991839 · Accepted solution]

What I finally ended up doing was duplicate the ears layers ( so I have two sets of layers that are identical) and then I swapped the layers using the swap layers trigger, so I had the ears on the head as the default and then swapped layers with a key trigger that had a physics behavior applied to that layer of ears.  It worked. 

Thanks for all your help, you gave me a couple ideas that helped me resolve it.

[alank99101739]

Clever!  I will have to remember that one!