Math behind transform.TransformDirection?

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I know TransformDirection can convert local to world coordinates. Can can tell me how the math behind the process works?

Answer 1

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Answer by EvilTak · Dec 09, 2014 at 11:19 AM

The transform of a gameobject has a matrix storing information like position, rotation and scale. TransformDirection multiplies the input vector with the transform's matrix and returns the result. InverseTransformDirection multiplies the input vector with the transpose of the transform's matrix. In 3d it is a 4 by 4 matrix, in 2d 2 by 2 matrices are used.

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wangunity · Dec 10, 2014 at 01:51 AM 0

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thank you . may be i should google a method by c or c++ about the process. also to find the same process with mono game project, because it have open source code.

starikcetin · Jul 29, 2021 at 03:34 PM 0

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This is wrong. What you are describing is TransformPoint, not TransformDirection.

Answer 2

Answer by starikcetin · Jul 30, 2021 at 10:20 AM

You have to decompose the rotation component of the matrix.

There is a Matrix4x4.rotation property. It returns a Quaternion. Simply rotate your direction vector with that Quaternion.

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Math behind transform.TransformDirection?

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