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I am creating a shot where:

  • gravity is turned off
  • multiple objects are "floating" in space
  • a few objects collide with eachother
  • each object has it's own forcefield in order to propel it forward.

I've tweaked the settings and gotten each object to move at the speeds I'd like. The problem I'm having is that I can't seem to figure out how to add some slight rotation to the objects to add to the realism. Any way to do this?

UPDATE 12/12/2020: I've researched more and I'm looking for something that in C4D is called "Angular Velocity" as described in this video around 7 minutes in:

C4D Antigravity Tutorial

After finding that, I found info about angular velocity being available in the particle force field emitter. Can I somehow rig up the particle emitter as my force field in order to add angular velocity to my object? I also found a Blender add-on called "Projectile" which looks promising. Allows you to do exactly what I want but is rather buggy.

There's got to be a setting like this in Blender that gives you the ability to rotate the object without any collisions occurring, can someone point me in the right direction?

UPDATE 12/17/2020: I found this helpful thread (How can I add motion to a rigid body?) that describes how to use keyframes on an "animated" rigid body in the first two frames of the animation, then switching animated off for the duration of the animation. That sets the velocity however you like it and is proving to be promising when combined with the answer below.Basically it's setting "Initial Velocity". Now I know! Here are some other helpful tutorials on this:

Blender 2.71 Rigid body - starting speed

Blender 2.81 - how to give object initial velocity for physics simulation tutorial

UPDATE 12/18/2020: I was having trouble with the animation not carrying through after the initial keyframing. It took a bit of reading, but I figured it out. This is covered in the video links above, the first one has it in the comments, and the second one he details it out in the video. From 2.80 on you need to set up the keyframes on a frame after frame 1 or it for some reason doesn't work. Here are the keyframe details:

Frame 2 and 3: Have the initial velocity keyframes set here. Rotation and location keyframes telling blender how fast you want your object to move.

Frame 3: "Animated" box (in Rigid Body settings) is ticked on.

Frame 4: "Animated" Box is ticked off.

After that, your initial velocity should work!

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This was done in Version 2.77a and should work in 2.8+ . (Blend file below)

There's very little to do to get this working in Blender...

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First up, make sure the physics cache has enough frames set up to accommodate the action.

What makes this work is the 'natural' dislike' physics objects have for each other. They don't like being together and even with the collision margin set to 0.002, they'll still want to move apart in a no-gravity situation.

So all you need to do is place two objects together and switch on the physics.

Details -

The (invisible) cube is a rigid body with physics set to 'Active' and it's ' Animated' box ticked permanently. It's not keyframed and left stationary.

The black (floating) object is also a rigid body and left stationary but still set to 'Active' and with it's physics keyframed to 'Animated' at frame 1. That's switched to 'Dynamic' at the frame the hand in the video is to touch it, or it is to be hit by another floating object.

When the collision isn't matched to a video'd object, normal physics should apply when they hit. Both objects could be animated and switched to Dynamic at the collision point

The forces at play as shown above are from the physics engine only. With the cube barely touching the floater, and 'Collision Margin' set to 0.002 (on them both) the repelling force between them isn't great and it gently drifts away.

How it drifts and the force behind it would depend on the angle and penetration of the cube.

The floater will want to slow down over time so the damping settings (physics) have to be set to zero.

Similarly the shape selection on both, 'Convex Hull' as against 'Mesh' will also make a difference.

'Passive' and 'Active' choices can also have a marked effect.

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If you have 3D objects in the workspace drifting and colliding, normal physics would take care the impact mechanations.

If on the other hand you want to control the angle and at what speed the 'victim' object takes off, the described example above would do that. The visible colliding object wouldn't need physics. It would be animated scenery only and would have no effect on those with physics properties.

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  • $\begingroup$ This is very helpful information! I've been keyframing the boxes to impact my main objects and it's been difficult to get them set up exactly right. The information on jus putting the objects so they're touching is very helpful, as well as the collision margin helping out with the speed it's "shot" away. I'm still not getting the fast rotation from the get go that I see in your example but I suspect it has to do with placement of the passive object. Thank you for your help! $\endgroup$ – Jboogsthethug Dec 17 '20 at 21:10
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    $\begingroup$ Your welcome @Jboogsthethug , I made my 'floater' elongated, much like the pen I saw in your linked Youtube video. Not sure if it's shape would have a bearing though, never thought to try that. I'm not on the Blender machine at the mo. but logic suggests the floater's origin-point would also affect the way it rotates. I note you mentioned a 'passive' object. I ticked 'Active' on both mine and see that I'd incorrectly omitted that fact. I'll fix that with an Edit... Good luck with your project. :) $\endgroup$ – Edgel3D Dec 19 '20 at 0:41

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