Rotating to Normal

Hi guys,

got a quick question. I was making a Copy Sop vs Instancing example for a friend, and found the following problem.

In Copy Sop, there is a rotate to Normal option, and when I tried to extract the normals from the template object and have the instancing geo comp do the same thing with the Rotate To options, I get a warning, saying some of the normals are co-linear to the up vector and won’t be rotated. You end up with a different looking final object.

How does Copy Sop actually deal with this? And how can I resolve this issue via instancing?

Please see attached tox file for the example.
Thank you.
CopySop_vs_Instancing.tox (958 Bytes)

Hi there,

A 3d rotation also needs a second vector to be able to align all 3 axis.
(Since if you would rotate an object towards 1 vector, it can still spin around that vector)

If you dont supply any up vector in the instance parameters, the normal up vector (0,1,0) will be used. And since at least 1 instance will have a ‘rotate to’ vector of 0,1,0, it has no idea how to handle those.

I’ve played a bit around and it looks like the copySOP rotates the up vector 90 degrees according the normal. I’ve did this using a pointSOP to add an up vector that is rotated like this.
See attachment.

Hope this helps.

Cheers,
tim
CopySop_vs_Instancing_with_up.tox (1.42 KB)

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Thank you!