Rotate vertices around pivot

Hey all, for a particular project I'm doing, I need to create a dynamic mesh to emulate the affects of linerenderers on a large scale. The problem I'm running into is that I'm not really sure how to go about have the 4 vertices rotate around the origin so the 2 triangles are oriented at the camera. Basically, I'm just trying to come up with a function that takes 4 vertices and an origin, than transforms them so that the faces created by them are at the camera (like the line renderer does). Any help would be greatly appreciated!

No, I can't just use the linerender class itself, because this will need to be highly optimized on a mobile device to limit both drawcalls and function mesh update calls.

Edit: I'm inquiring as to the quaternion math itself, not the theory or technicality involved in rotating points in 3d space.

 

Code (CSharp):

1. for (int n = 0; n < vertices.Length; n++) {
2.            
3.    vertices[n] = rotation * (vertices[n] - centerPoint) + centerPoint;
4.            
5. }

Where vertices[n] is the vertex you want to rotate, rotation is a quaternion describing the rotation (duh) and the centerPoint is the point you want to rotate around.

Yes, I know this is close to three years old

 

Good stuff.

1) Reversing Matrices operation "Transform Move" by (vertices[n] - centerPoint).
2) Applying rotation via rotation *.
3) Applying "Transform Move" back again with + centerPoint.

Very good and useful.

 

if anyone is looking, this tool allows you to transform vertices of a mesh and position vertices by handle manipulation or by directly entering the x,y,z coordinates of each vertex.
https://assetstore.unity.com/packages/slug/166155