# Convert rotations from right hand to left hand?

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Is there a way to calculate the rotation values in a left handed system, given the rotation values in a right handed system? HOW? Thanks!

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Hi,

I had the same problem with a Maya exporter -> DirectX (Maya = right handed, DirectX = left handed.

For the rotation, I found the following : If you have your rotations around each axis, and applied in the order : X, Y then Z, in a right handed system, then in a left handed system, it will be : X, -Y, -Z.

I did found that in a totally empiric way, but I've been using my exporter since half a year now, and I've never had any problem.

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Yeh thats what we're doing. Using Maya for our level editor in a DirectX based game. I tried what you said and it doesn't seem to work, can you show me exactly how you grabbed the rotation values from maya? Also, how were you constructing your projection/view matrices in DX? RH or LH?

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Can you just use a right hand coordinate system instead (rather than converting everything)? We had the same Maya problem, and switching our game to the LH system was pretty painless; 2 steps really (if I remember correctly):

1) Switch the D3DX functions that end in RH to LH
2) Switch the renderstate for culling to the reverse of what you have

I think that's pretty much all I did and never had a problem afterwards. The only downside is that mesh viewer uses a LH system, so it lessens it's value as a tool slightly.

NOTE: This assumes you use the D3DX functions for creating your transform matricies.

Matt Hughson

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Maya uses RH system though, and we were using D3DX functions to convert between RH and LH in our game. Neither is working for us though. I need help!

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Ok, here's the function which extract a transformation matrix from a dagPath, and convert it to left handed :

	MFnTransform	transform(dagPath);	float		mat[4][4];	MEulerRotation	eulerRotation;	double		scale[3];	MVector		translation;	// extract the transformations from the transform	transform.getRotation(eulerRotation);	transform.getScale(scale);	translation	= transform.translation(MSpace::kWorld);	// convert it to left handed	translation.x	= -translation.x;	eulerRotation.y	= -eulerRotation.y;	eulerRotation.z	= -eulerRotation.z;	// rebuild a transformtion matrix from the modified transformations	MTransformationMatrix	transformationMatrix;	transformationMatrix	= transformationMatrix.identity;	transformationMatrix.rotateBy(eulerRotation, MSpace::kWorld);	transformationMatrix.setScale(scale, MSpace::kObject);	transformationMatrix.setTranslation(translation, MSpace::kWorld);	// extract the new matrix	MMatrix mayaMatrix = transformationMatrix.asMatrix();	mayaMatrix.get(mat);	// store it	matrix._11	= mat[0][0];	matrix._12	= mat[0][1];	matrix._13	= mat[0][2];	matrix._14	= mat[0][3];	matrix._21	= mat[1][0];	matrix._22	= mat[1][1];	matrix._23	= mat[1][2];	matrix._24	= mat[1][3];	matrix._31	= mat[2][0];	matrix._32	= mat[2][1];	matrix._33	= mat[2][2];	matrix._34	= mat[2][3];	matrix._41	= mat[3][0];	matrix._42	= mat[3][1];	matrix._43	= mat[3][2];	matrix._44	= mat[3][3];

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paic, youre awesome thx so much =)

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