koobas.hobune.stream
Local Point to World Point without TransformPoint()
Greetings,
I really would like to know, how to convert a local vector3 position to a world vector3 position. And I wanna do this without having the corresponding position on a transform. Tryed searching, but all I find is TransformPoint() and I know pretty much nothing when it comes to math. I only have two Vector3s, and creating a gameobject just to use that method seems pretty stupid. pls help me out! :)
Well, like any coordinate conversion, it helps to know the reference frames you're dealing with.
Where the this point co$$anonymous$$g from? What is it relevant to?
What are you talking about? What am I missing?
There are 3 positions here. The World wich obviously is (0,0,0) a Point A that is in the world, lets say at (5,8,2) and theres a point B in Point A, lets say that one is at (4,2,9)
Now I wanna know where Point B is in the World.
If your heirarchy is something like this:
Point A (5,8,2) (with child Point B (4,2,9))
Then add Point A's reference frame to Point B. Point B would be:
(4+5,8+2,2+9) --> (9,10,11)
You can achieve what you want using the Matrix4x4 class.
Give a position(Vector3), rotation(Quaternion) and scale(Vector3), just like a Transform has:
Matrix4x4 m = Matrix4x4.TRS(position, rotation, scale);
This works like Transform.TransformPoint(localPos)
Vector3 worldPos = m.MultiplyPoint3x4(localPos);
This works like Transform.InverseTransformPoint(worldPos)
Vector3 localPos = m.inverse.MultiplyPoint3x4(worldPos);
You're probably going to have rotation as Quaternion.identity and scale as Vector3.one if you only want to deal with positions.
In that case it's actually simpler to just say :
Vector3 worldPos = localPos + position;
Vector3 localPos = worldPos - position;
position is the same Vector3 you would have given to the Matrix4x4.TRS method. It's that simple if there's no rotation or scaling.
This was really helpful, thank you for putting it together.
Why do you have to convert the position from local to world space? Are the Point A and Point B parented to something? If not, simply use transform.position(world space)
