I'm trying to animate objects falling onto a conveyor and falling off the end. I'm using a conveyor belt constructed by using an array and curve modifier to pattern the segments around the curve. However, rigid body objects pass straight through the conveyor belt when I use "Deformed" as the source. I can't use "Final" as the source or apply the modifier as then I cannot animate the belt rotating.

Is there a work-around for this?


2 Answers 2


The rigid body simulation will not work correctly with an 'arrayed' mesh fit to a curve in this way as the 'arrayed' instances are not separate bodies but are actually just the original mesh, deformed. This means that while they could be made to be "solid" to the rigid body world (by setting collision to 'Final') they will not interact as if they were separate, moving bodies.

In order to create such a simulation you need to have separate rigid bodies for each 'panel' of the conveyor. Rather than use a Curve Modifier you can instead use a Follow Path constraint on each panel.

Start by creating a single 'panel' and set as a Passive Rigid Body. In the Rigid Body settings, set it to 'Animated'. This will allow it to interact with the simulation while still being controlled outside the simulation.

Create the curve for your conveyor belt - I used a Nurbs Circle as a start point and extruded each side outwards to 'stretch' it.

Add a Follow Path constraint to the panel with Target set to the curve. Configure it so that changing the Offset moves your panel along the path.

Duplicate the panel as many times as required for your complete conveyor. Amend each panel's Offset in the Follow Path constraint to position it in the correct place.

Once complete you can go to the Curve properties, enable 'Path Animation' and keyframe the Evaluation Time to animate.

This produces the following result :



This was done with version 2.77a (Blend file below)

The conveyor is paused mid-stream to demonstrate that the cube is indeed 'sitting' on the belt.

There are a number of ways to make the cube follow the conveyor but arguably, the simplest and safest is to use Physics and a Child-of constraint initially. Once working properly, bake it all.

This will free the cube of physics and constraints. It can then be tweaked safely.

Note - the Child-of's Influence slider prevents the cube from moving forward until it's landed on the belt.

With it working as required, --> at frame 1 <-- physics can be returned to the cube, but this time with the Dynamic box keyframed OFF, and Animation ON.

At the frame where it's to fall off the end, keyframe the physics boxes in reverse. Dynamic ON, Animation OFF.


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