Change orientation copied object

[Elggetto 2]

Hello,

I have a super simple problem, but I can't seem to figure it out.

Basically, I have a two points line, with normals pointing in opposite directions. I'd like to copy something on each of he two point, but pointing in the direction of the Normal.

Right now, it's perpendicular to the normal.

I tried a few combinations of cross() and @N, @up, set(1.0, 0.0, 0.0), set(0.0, 1.0, 0.0) and everything in between. It rotates, but never in the correct orientation.

I can't transform the input geometry (like rotate 90 degrees), only the normals/up of the line.

 

What would be the best way to do it? Thanks!

2022-06-21_HelpNormals2.hipnc

[Atom 1,489]

Try adding a transform and rotating 90 degrees on the X-axis.

[Elggetto 2]

Hi! Yes, I could do that, but I wanted to learn how to use the pointwrangle and modify the @N or @up directly without using a transform beforehand. I'm still having trouble with the whole @up, @N and @orient thing and I feel like I should know this.

[tamagochy 71]

@N its a direction and its align with Z axis of the object. Up vector align with Y axis of the object. Base on it you can create orientation of the N and Up and object in origin point.

[Elggetto 2]

Yeah ok I guess transform before the copy is the way to go then... It makes more sense I think.

Do you know of any documentation/crash course/video that dives deep into the concept of @up and @N in relation to copytopoints?

All Tutorials I find just tell you what to do, but don't explain in detail what does what. Like what you said with the @N alignin with the Z axis and @up, the Y. This is the first time I read that. Thank you for that info!

[dleonhardt 46]

27 minutes ago, Elggetto said:

Yeah ok I guess transform before the copy is the way to go then... It makes more sense I think.

Do you know of any documentation/crash course/video that dives deep into the concept of @up and @N in relation to copytopoints?

All Tutorials I find just tell you what to do, but don't explain in detail what does what. Like what you said with the @N alignin with the Z axis and @up, the Y. This is the first time I read that. Thank you for that info!

https://www.toadstorm.com/blog/?p=493

 

[ryew 71]

1 hour ago, Elggetto said:

Yeah ok I guess transform before the copy is the way to go then... It makes more sense I think.

Do you know of any documentation/crash course/video that dives deep into the concept of @up and @N in relation to copytopoints?

All Tutorials I find just tell you what to do, but don't explain in detail what does what. Like what you said with the @N alignin with the Z axis and @up, the Y. This is the first time I read that. Thank you for that info!

Peter Quint's old Particle Leaves video did a great job of explaining this; it used the Copy SOP, but the principles are (should be) the same (can't be embedded, unfortunately):

 

[Elggetto 2]

These seem perfect. Thanks a lot guys!

[vicvvsh 161]

15 hours ago, Elggetto said:

Yeah ok I guess transform before the copy is the way to go then... It makes more sense I think.

Do you know of any documentation/crash course/video that dives deep into the concept of @up and @N in relation to copytopoints?

All Tutorials I find just tell you what to do, but don't explain in detail what does what. Like what you said with the @N alignin with the Z axis and @up, the Y. This is the first time I read that. Thank you for that info!

Houdini help? https://www.sidefx.com/docs/houdini/copy/instanceattrs.html

[Elggetto 2]

18 hours ago, vicvvsh said:

Houdini help? https://www.sidefx.com/docs/houdini/copy/instanceattrs.html

Well thanks for that. I must have missed it. This is clearly written haha.

So what I learned: The copy will always orient its Z axis with the normal of the point. THEN it will rotate according to the up value. Of course this only happens if there is no orient (or transform) attribute first.

Lets gooo! Thanks everyone. 

Edited June 25 by Elggetto
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