Programatically calculate child offset in world space

Questions & Answers
1

Hi All,
Apologies if this has been answered elsewhere, with the terminology I know I can’t find the answer.

I have an Offset in Position / Rotation relative to a Point. Call the Offset O and the Point A;
I have O as a Matrix4x4 but I can get Vector3/Quaternions from that.

Point A could be anywhere, and be rotated.

I want to get the world space of O, offset from Point A.

I can solve this a hacky way… I spawn a Child GameObject under Point A, and set it’s localTransform to the Offset O. I then take the world Position of that new Child.

Q: How can I do this in code?
(I assume my way is horribly inefficient, and that a method using Vector maths would be the better solution)

2

Seems like you want to get the world space transformation from the offset point relative to transform A.

Transform local to world position:

Vector3 offsetWorldPosition = pointA.TransformPoint(offsetLocalPosition);

Transform local to world rotation:

Quaternion offsetWorldRotation = pointA.rotation * offsetLocalRotation;

Calculate localToWorldMatrix:

Matrix4x4 offsetOfromA_localToWorldMatrix = pointA.localToWorldMatrix * offsetOMatrix;
Vector3 offsetWorldPosition = offsetOfromA_localToWorldMatrix * Vector3.zero;