# Physics for falling leaves?

Posts: 381
edited December 1969

Continuing my Carrara learning program, I'm trying to make a very simple tree and house scene to show seasons. Winter tree (trunk and branches) -> buds grow out into leaves light green -> full set of leaves dark green -> leaves turn to orange then to brown and then fall to ground.

Right now I am testing ideas so my tree is just a vertical cylinder and I'm playing with a single leaf which for now is a rather flat cube.

Everything is fine up to where the leaves fall.

With a limited number of leaves, I could keyframe each from branch to ground. But, I was thinking the tree would have 100 leaves, which would be a pain to animate individually.

Is there any way to have physics off until I need the leaves to fall and then turn it on and let gravity do its trick?

----------
A second question:

Eventually I would like to have snow fall on the scene (just a very simple toon scene with a house, yard and single tree). Is there any way to do that with particles dropping?

Could I have a clear box around the entire scene that would "catch" the particles?

• Posts: 1,931
edited October 2013

Yes,
You make a physical calculation then you changes “Physics” to “Image”, which will create keyframes for each leave.
You groups all leaves in a clip which you can move back at the selected moment.
If you do not create a clip, you select all the keyframes and you move them in the timeline.
For the snow, I think it's a preset for that (?)

Post edited by DUDU on
• Posts: 9,021
edited December 1969

Actually a good way would be to turn off the scene gravity under the Scene's physics tab, and use a directional force instead. The directional force's effect can be keyframed, so you could have no force, and when you want it to kick in, add a value. You may even wish to keyframe lower and higher values as well as small directional changes to better mimic how leaves would fall to the ground. The icon looks like an arrow to help you aim it.

For leaves that drop at different rates, you may be able to adjust the mass or whatever on the leaves. Remember, that the surface parameters of physics objects will determine the bounce, friction etc. But you must also remember the surface parameters of the non-physics objects in the scene as well, especially those items the physics objects interact with!

• Posts: 23,784
edited December 1969

using particles much simpler and easier for leaves or the fountain with a surface replicator.

• Posts: 373
edited December 1969

Why not use the tree generator? convert to mesh for the trunk and one mesh for leaves and animate using a directional force

• Posts: 15,387
edited October 2013

dot_bat said:
Why not use the tree generator? convert to mesh for the trunk and one mesh for leaves and animate using a directional force
Agreed.
Wow, all of you contributors... this is some great food for thought!
Post edited by Dartanbeck on
• Posts: 1,931
edited December 1969

… and the “Must”, it is to combine several of these techniques in the same scene!

• Posts: 381
edited December 1969

Thanks to everyone for the replies.

dot_bat said:
Why not use the tree generator? convert to mesh for the trunk and one mesh for leaves and animate using a directional force

I'm very new at this... how can I do this? I get a trunk, then have to render leaves, but in the assemble room I still just have a trunk... ??

• Posts: 381
edited October 2013

OK, I found the Show Leaves button, but then still don't see the leaves as separate meshes...

Post edited by That Other Persona on
• Posts: 15,387
edited December 1969

OK, I found the Show Leaves button, but then still don't see the leaves as separate meshes...
Show Leaves will show the leaves in the Assembly room, when using a plant made in the plant editor - obviously Dartan... that's where the "Show Leaves" button is! - "I know... just give me a sec, will ya?" - Sorry, Dart. Please... continue:

What I believe dot_bat was saying, is to create a tree using the Plant Editor and converting to vertex object. While I've never done this with a Carrara Plant yet, here's how to:

Create your tree to your liking. In the Assembly room, select the tree and Edit > Convert to other modeler > Vertex Modeler

According to what Dot_Bat instructed, I am assuming that you'll have a vertex object for the tree and, perhaps a grouping of vertex objects as the leaves - or, perhaps a single vertex object for each leaf? Not sure how that works without experimenting, myself.

• Posts: 23,784
edited December 1969

I have imported a converted one into Poser and clothified the leaves!
if you export the obj you can reimport it with the option to create seperate meshes for shading domains checked then posibly make them all physic animated, the thought scares me!

• Posts: 15,387
edited December 1969

I have imported a converted one into Poser and clothified the leaves!
if you export the obj you can reimport it with the option to create seperate meshes for shading domains checked then posibly make them all physic animated, the thought scares me!
What scares you might make me do something horribly wrong in my pants - so I'll shy away from that, if you please ;)
• Posts: 373
edited December 1969

what i was thinking is create the tree and the leaves, convert to vertex. the leaves are a seperate shading domain, select by domain only the leaves and copy them and delete the selection of leaves then com or control v to place the copied leaves in the tree. what you are left with is a mesh separeate for the trunk and a mesh for the leaves.
havent tried this myself but should work

• Posts: 15,387
edited December 1969

It will be interesting to hear if the leaves of this single mesh can fall dynamically or if they fall as a single mesh. The important thing will be to include varying forces to get them to dance their way to the ground as leaves do. I am somewhat envious that I am not the one doing this project. Maybe some day.

• Posts: 373
edited October 2013

yeah i dont know if they would fall individually, i kind of doubt it, but you could still go in and change that. a bit tedious but possible and would look great i think. maybe a little too involved for the poster at the moment. i know they were just experimenting with a simple object with gravity for learning sake. but still for fall it just needs to be a few at a time

Post edited by dot_bat on
• Posts: 238
edited December 1969

The leaf physics can be difficult to setup without being able to separate the leaves into individual instances. Heres another suggestion. Insert a default Plant(tree) in scene.

1.In the Plant editor.
-Checkmark->Full-Detail Mesh.
-Edit->Convert to Other Modeler...and select the Vertex Modeler, press OK.

2.In the Texture room.
-Create a new master leaf shader and set the Alpha channel to 0.Should be invisible now for testing.

3.In the Assemble room.
-Insert a Surface Replicator in scene.
-From the Browser->Objects tab->Leaves, insert the 'Leaf' object in scene and rename it to 'Leaf' or similar.
-In the Leaf objects Motion tab, set to Physics method.

4.In the Surface Replicator editor.
-Source object: Plant.
-Replicated objects:Leaf.
-Minimum distance between objects:0.05ft.
-Then click on the->Create real instances: 'Create' button, press OK.

In the assemble room you can now click on the Simulate Physics icon. The 100 leaves should fall to the ground. You can adjust the hotpoint of the original surface replicated leaf to better match the branches before creating real instances, set higher leaf counts in the replicator and adjust shaders as needed for animation etc.

For the snow falling, you can setup a particle emitter to emit from a plane or similar object over a scene. The only issue with particles is that they don't have any volume and may not build up or collect on surfaces like real snow would.

As a side note to step #1. I'm using version 8.1 Pro(build 153) and the physics have an error with a default plant in scene. This is why I have to convert to other modeler. Other Carrara versions might work without that conversion step.

• Posts: 1,931
edited October 2013

tbwoq, it is very interesting!
Don't the leaves touch the trunk ?, I ask that because, even with the distance from collision of the scene to “0”, it could disappear at the first image…
I will test, thank you!

Post edited by DUDU on
• Posts: 1,931
edited December 1969

tbwok, splendid, it is the autumn in my PC Thank you a lot !

• Posts: 238
edited December 1969