koobas.hobune.stream
Need equivalent of Transform.TransformPoint() but without using transforms
I want to be able to do the equivalent of this:
var localpos = Vector3(0,0,2);
var tPoint = transform.TransformPoint( localpos );
But without using a transform - so instead:
var pos = transform.position;
// should I use a quaternion instead?
var angle = transform.eulerAngles;
var localpos = Vector3(0,0,2);
var tPoint = // ???
(I realise in this example, it's a bit redundant - my real code would require an empty gameObject added which I don't want.)
The best way of doing that is using a Matrix4x4 any other method would result in a lot of calculations on your side. You don't need scaling, right? Why don't you want to use a empty GO, it's the easiest way of doing that and you have visual debugging support integrated ;)
Anyways, use Matrix4x4.TRS to setup your matrix and don't use eulerangles. Eulerangles have a big problem that they can't represent all possible rotations (transitions to achieve the resulting rotation). That's why we have Quaternions. Even the TRS function needs a Quaternion.
If you have created your matrix you can multiply your point with the matrix. The same matrix is already used inside of a Transform. You can get the matrix with transform.localToWorldMatrix.
Some further information on matrices of that type:
http://en.wikipedia.org/wiki/Transformation_matrix
edit
Just came to my mind: I think that should work too:
var rotation : Quaternion; var position : Vector3; var localpos = Vector3(0,0,2);
var tPoint = rotation * localpos + position;
(of course without scaling!)
