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I want to create a simulation. It will be like: A bowl of candy and a tong. the thong will dive in and will pick one of the candies. I want candies to collide with tongs physic etc.

How can I achieve something like this?

Here is what i'm thinking: For the scene:

Bowl: Rigidbody (Passive) Candies: (Particles + molecular script) Tong: Rigidbody (Active) + Collison

For the animation: Just right one of the candies and parent it to the tong?

I don't know I might be wrong. Any help would be helpful. Or is there any other way to achieve this kind of animation?

Found a photo basically would be something like this: enter image description here

Thanks in advance.

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  • $\begingroup$ For future reference, you can paste your images into the post itself rather than as a link. This improves readability and makes your question easier to answer. $\endgroup$
    – Jakemoyo
    Jun 2, 2022 at 6:52
  • $\begingroup$ You already seem to have a decent Idea of how to start. Why not give it a go and ask questions if you encounter issues and get stuck? $\endgroup$
    – Jakemoyo
    Jun 2, 2022 at 8:21
  • $\begingroup$ Shouldn't a few particles be rigid bodies so you actually can move and grab them? (I am not sure if the grab will work without further adjustments.) $\endgroup$
    – Blunder
    Jun 2, 2022 at 8:47
  • $\begingroup$ I also would use a simple rig to animate the tong. Then add a collision modifier. I still don't think you can grab particles (candy). But honestly, I never tried the molecular add-on. I would make the candy (or just a part of them) a rigid body, cloth, or soft body to get the physic simulated. $\endgroup$
    – Blunder
    Jun 3, 2022 at 13:18

1 Answer 1

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Here is an example with two Cloth simulations. A Soft Body simulation and Rigid Body simulation should work, too. The physic settings for Rigid Body are a bit different.

picking candy animation

You need the following:

  1. a bowl object with Collision modifier
  2. a rigged tong with a Collision modifier. With the Skin modifier you can create a simple tong mesh and armature quickly. Just extrude 4 vertices, and mirror them. Extrude the root, and create the armature with the Skin modifier button. Rename the bones and add a postfix (.L/.R) so you can mirror and symmetrize them. Apply the skin modifier and bind the mesh to the armature with automatic weights.
  3. optional, a bunch of static candy (the white ones). Use your favorite physic sim or particles to fill the bowl. Apply modifier/transformation so it's static.
  4. more sweets with a Cloth simulation (yellow ones). When you have candies of different colors and shapes it might be a good idea to join them into different objects (making groups) and add a Cloth modifier to each candy object. Enable Collision and Self Collision for the Cloth and add a Collision modifier.
  5. the chosen candy that you want to pick (the red one). Add a Vertex Weight Edit modifier, a Cloth modifier, and a Collision modifier. Also, add a Child Of object constraint and choose one of the tip bones as target.

Settings:

  • enable Pressure for the Cloth to make the candy a little more rigid (red one in the example) -or- enable Internal Springs if you like them more squishy like gums (yellow ones in the example)
  • adjust the Collision Distance value in the Cloth settings so it fits your object sizes.
  • for the chosen candy create an empty Vertex Group and add it to the Pin Group in the Cloth settings. The Pin group is needed to grab the candy.

Simulation and Animation

The first 149 frames are just for the Cloth simulation so it can scatter the yellow spheres and they settle down.

For the red candy, the weight for the Pin group and the Influence value of the Child Of constraint are set to 0 for these first 149 frames. The weight is controlled by the Default Value of the Vertex Weight Edit modifier. The Pin weight is basically the switch between simulated and animated. With a Pin weight of 0 the Cloth simulation controls it. A weight of 1 pins the object and you can keyframe its position or let its parent control its position.

settle down

To grab the candy you need to do three things:

  1. set the weight of the Pin vertex group to 1 by setting the Default Value of the Vertex Weight Edit modifier to 1. The Cloth simulation no longer controls the object and you can animate it now.
  2. set Influence of the Child Of modifier to 1 so that the picked candy becomes a child of the tong's tip bone.
  3. move the picked candy to the simulated position → keyframe its position. The Cloth simulation only moves the mesh and leaves the object's position untouched. Watch the origin (orange dot) the example animation. When you "pin" the object in step 1, the mesh is reset to it's original position and "teleports" the candy back.

    To get the exact position, copy of the simulated candy. Rename the objects. The copy becomes the new original and the old one will be a helper object. Apply the cloth modifier of the simulated candy (=now helper object). Then run the simulation again, and go to the desired frame. Now move the candy to the helper object (Shift+S) and keyframe its position.

Note: there are two keyframes at frame 1 and frame 149 to keep the values constantly at 0 (=sim phase). Frame 150 and 179 keep the values at 1 (=grab & drag animation), and frame 180 sets them back to 0 (=drop the candy). Alternatively, set the Interpolation Type to Constant in the Graph Editor.

pick the candy

To drop the candy just do step 1 and 2 from above with 0 values. That is, set the weight of the Pin group and the Influence of the Child Of modifier to 0, and the physic simulation will make it drop.

A Rigid Body Simulation works the same, except that you need no Pin group, no Collision modifiers. Keyframe the Animated checkbox to switch between simulation and animation. The tong must be a passive rigid body and Deform must be enabled.

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  • $\begingroup$ Wow! You are amazing Blunder! Thanks for the detailed answer. $\endgroup$
    – Jasoned
    Jun 4, 2022 at 3:31
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    $\begingroup$ Great answer ‼️👍🏻 $\endgroup$
    – Chris
    Jun 4, 2022 at 6:23

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