Except that you can’t change certain things in those callbacks, and I suspect that changing a “substitute object” is one of them. I don’t know if it is for certain, but it’s worth pointing out because it may cause problems (like a crash).

Good catch, <del>I’d perhaps look into #postRenderFrame then.  #PreRenderFrame says “The renderer has already called GetRenderMesh() on all the object instances, and the materials and lights are already updated.” So post may work (as long as he doesn’t need it to happen on the first frame)</del>

I don’t know of anything. I know globals are evil and all that, but…

You could make a script, with pre/post render callbacks, where each toggles a boolean global.  isRendering = true/false.

This would have to be in your startup folder or something like that so that the callbacks get registered in each max session… otherwise your controller pointing to “isRendering” will freak out.

I’d considered that but was hoping there was a pre-defined means of obtaining the “Max Status” rather than having to do it manually. The overall idea may work though - any “gotcha’s” you can think of which would prevent this working reliably? Always assuming you can do the replacement in such a script - I tried (briefly) creating a new Box at a given time. It wouldn’t render the box, but it appeared as soon as the render ended. Needs more investigation, I think.

I can’t think of gotchas with that.  In the SDK, .net under ManagedServices there is a “AnimationFrameChangeListener” class that may be useful (might work at both render time and slider changes).

It may be easier with something like this to simply create a custom “render frames” script… something that would actually stop render, advance slider time (and change mesh as necessary), render next frame, and then at the end combine them into a movie.  I kind of do that in my script: <font color=red>Render 3D v1.3</font>, but I’m not breaking render per say; though you can look at the code and see how I’m adding support for .MOV by combining bitmaps.