Booleans + materials + and motion blur = materials not rendering?!
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Hi there,
I'm attaching a scene to help illustrate what I'm talking about:
I have some objects being progressively hidden (and, in other contexts, revealed) through animated Booleans. Those work as expected, but for some reason, if I enable Motion Blur, at (repeatable) frames, the objects "cut" by the Booleans suddenly lose their assigned material -- and in some cases, even if they're not impacted by the Boolean animating on a particular frame.
To see what I mean, with motion blur enabled, render the attached scene at frame 788. Advance one frame to 789. In 788, you will most likely see a blue material on the smaller cylindrical bits that march along a spline wrap; in 789, those cylinders will have lost their material, as well the red thin editable object above one of the white cubes (you'll see what I mean in the scene!). And on frame 790, things are back as they should be.
Then disable motion blur and re-render frame 789. The materials should render properly.
What is going on that motion blur has this effect on certain objects, but only at certain times? I tried messing with the objects used as "cutters" (either tweaking their size values or number of subdivisions), but I can't come up with a true solution. Is there something I'm missing?
Just in case it's helpful to know: I'm not married to the Boolean idea: I just want a way to hide (or reveal) objects over time. I thought about fields and vertex maps, but my limited understanding suggests I'd have to significantly increase object resolution for that to work...somehow. I'm happy to be educated! Thanks for looking!
Regards,
BlakeEdit: Okay, I can't seem to upload my scene: I just get a message that says "ERROR" with no explanatory text or anything. I placed the file on Dropbox here:
https://www.dropbox.com/scl/fi/vvi0b44mz13owr0yraqqp/S03E04-seq-01D_boole_test-02.c4d?rlkey=n4yo5lqzbzv6j89p9wt9b39it&st=1azjv96q&dl=0
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Hi Blake,
Motion blur is based on the points of an object, and the points can move differently than the object axis, e.g., in character animation.
Boole creates new points and amount of points. Which destroys the idea of Motion Blur.
The Error message is
Warning: Object: "Placeholder" contains inconsistent topology. Deformation Blur output will be inconsistent.In some cases, a merged Motion Vector pass will work in Post, but the chances are rare that it fits, or if so, how much work that might be to create all needed masks, etc.
Sorry to have no better solution.
My best wishes
The Error is from the c4d file, over 1MB*
*If the C4D file is above 1MB and can't be uploaded here as is, please use only DropBox, Google, WeTransfer, Adobe, or Apple Cloud services. Please upload the file as is, no rar or zip. Paste the URL as is (no tiny url or HTML wrapper). Sorry for the long instruction, but safety first. Yes, I will not touch anything else. But please note, I have no solution for Redshift changing point amount, etc., Motion Blur.All the best
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Ah, okay, thanks for the explanation! Is there a better solution to progressively revealing (or hiding) an object? I guess something like MRI slices, but being able to keep the "slices" on one side of the "beam" visible and the others hidden? That's probably not terribly clear, either! Thanks again!
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Hi Blake,
If an MRI slice works for you (excellent idea), then please check out this file if this goes along with your idea.
All the best
