I am trying one of the inevitable n00b exercises, the roller coaster or race track model. I have almost got the hang of it (create nurbs-path, create one track module, Array Modifier to Fit Curve, Curve Modifier, presto!). All of this works, and I get a 3d track suitable for rolling marbles or toy cars etc. However I find that while the Modifiers are still on the stack, the replicated track surface is not "solid" in Rigid Body World. My little rolling toy falls through the track immediately. After I Apply both Modifiers, the track becomes solid and I can then roll the toy down it.

However, as I observe the toy's behaviour on the track, I want to tweak the nurbs-path in various ways (slope, camber, radius etc) and it seems that the only way to do this is to Ctrl-Z back to the point just before I Applied the Modifiers. Sometimes, if I'm not careful, I lose other useful changes in the process of unwinding the modifiers so that I can tweak the nurbs-path.

Is there any way (a) to keep the modifiers active and yet have the track solid enough for testing, or (b) quickly to undo Applied Modifiers on selected object only? Or is the workflow loop I am now doing (test RB sim, ctrlZ ctrlZ until the modifiers are back on the track-object stack, tweak curve, apply mods again, rinse, repeat) actually the best/only way to do this?


1 Answer 1


I quote from the Answer to the other Question (see comments above) of which mine is (sort of) a duplicate.

You need to change the Source and the Shape of the rigid body collisions. In the physics tab of the properties panel, change the Source from "Deform" to "Final". Only "Final" takes the modifiers in to consideration, hence your trouble. The other setting you need to change is the rigid body collision Shape, set it to "Mesh".

This solves my problem: as soon as I select Final, the replicated object becomes solid in RB world and I can still tweak the controlling curve to reshape and refine it, without any Ctrl-Z nonsense.


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