Camera Billboard - Rotate only around Y Axis

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blaxxun
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Camera Billboard - Rotate only around Y Axis

Post by blaxxun » 09 Jan 2019, 12:01

Hi guys,

I have a pointcloud with tree billboards instanced in ICE.
Now i want that the tree billboards always face the camera BUT the billboards should ONLY rotate around the Y axis.

At the moment they also follow the camera when i move over or under the ground surface height.

How can i "lock" X and Z axis?

I tryd to modify without sucess: Billboard Orientation, Align Particle to Position, Align Particle to camera.

Thanks! :)

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rray
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Re: Camera Billboard - Rotate only around Y Axis

Post by rray » 09 Jan 2019, 13:04

Hi there

You can copy the Rotate Toward Target compound from the "Turret constraint" compound and use it to modify the particle orientation.
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softimage resources section (formerly known as rray.de/xsi) updated May 30 2018

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blaxxun
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Re: Camera Billboard - Rotate only around Y Axis

Post by blaxxun » 09 Jan 2019, 14:41

Okay, i tryd that but "Rotate Toward Target" seems to be a "per object" compound.
I try to modify it from "Pose" to "Rotation" since this is "per point".

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rray
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Re: Camera Billboard - Rotate only around Y Axis

Post by rray » 09 Jan 2019, 14:57

Yes exactly, this should work (Particle Orientation->SRT to Matrix->Pose). This should make the compound work in per point mode.
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rray
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Re: Camera Billboard - Rotate only around Y Axis

Post by rray » 09 Jan 2019, 23:19

had a try, was some fiddling around to find out what axis to rotate around, and what is the axis that "aims"

Couldn't get the Pose Out to work, the connection always stayed black. No idea why, I just got the orientation directly out of the compound.
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"as a maya discussion grows longer, the probability of a suggestion involving deleting the preferences approaches one"

softimage resources section (formerly known as rray.de/xsi) updated May 30 2018

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blaxxun
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Re: Camera Billboard - Rotate only around Y Axis

Post by blaxxun » 14 Jan 2019, 13:25

Wow, nice! Thanks!

I had to rotate my trees(Y is up) around X by -90 degrees because they where flat on the ground.
Im sure there is an easyier, more clean way to do that, but for now it works just fine.

Vielen Dank! :-bd

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dwigfor
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Re: Camera Billboard - Rotate only around Y Axis

Post by dwigfor » 16 Jan 2019, 05:51

You should be able to simplify the RotToEuler to EulerToRotation. I don't have XSI open, but I think you can multiply your RotateTowardTarget rotation (input1) with a EulerToRotation (set to -90 X) (input2). One of the few times that the order you multiply matters! RotA*RotB doesn't equal RotB*RotA. You always want parent * child.

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blaxxun
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Re: Camera Billboard - Rotate only around Y Axis

Post by blaxxun » 16 Jan 2019, 07:45

Thats actually what i did, or how do you mean that ?
Could you show it ?

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dwigfor
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Re: Camera Billboard - Rotate only around Y Axis

Post by dwigfor » 16 Jan 2019, 17:30

Should be same result, just a little cleaner code... :)
ICE_Tree_Billboards.png
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dwigfor
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Re: Camera Billboard - Rotate only around Y Axis

Post by dwigfor » 17 Jan 2019, 17:57

My apiologies, it's Child * Parent. Order matters. Sorry bout that!