Forums Technical Discussion Make normals orthogonal to custom vector

Make normals orthogonal to custom vector

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eaniix
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Joined: Nov. 2021
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Hi there,

I'm trying to realign my normal vectors on the left sphere to look like the normals on the right sphere using the red vector which is just {0, 1, 0} in this example. For this example I just set N.y to 0 and normalized N but I need this to be interactive so the yellow normals are always orthogonal to the red vector.

I thought it should be fairly easy but I just can't figure it out right now.
I hope you can help me out with this!
Edited by eaniix - Oct. 16, 2024 14:42:22

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vector.jpg (185.5 KB)

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animatrix_
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Hi,

You mean like this?

@v = normalize ( set ( @N.x, 0, @N.z ) );

Senior FX TD @ Industrial Light & Magic
Get to the NEXT level in Houdini & VEX with Pragmatic VEX! [www.pragmatic-vfx.com] https://lnk.bio/animatrix [lnk.bio]
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eaniix
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I figured it out!

I used the cross product between both vectors and then rotated that 90 degrees around the red vector.

Here's the code I used:

vector dir = normalize(chv('direction'));
v@N = cross(v@N, dir);

vector4 rot = quaternion(radians(90), dir);
v@N = qrotate(rot, v@N);
v@N = normalize(v@N);
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