Guide For Exporter Writers

[rgigante]

Hey bkircher, XSI has the same Maya axis orientation...but a couple of things:
1. helped by my memory , i remember that maya has the option to switch from XZY to XYZ coords system, enabling the user to have the Y-vector coming "in" the screen. In this case u can easily use the 4x4 rotation matrix as it comes out from Maya.

2. In the case your axis sys is XZY, well starting from your 4x4 matrix simply switch the index corresponding to Y with the index corresponding to Z elements in your matrix. The only thing you have to take care is the eventual sign change you can encounter when switching indices.

So starting from
m00 m01 m02 m03
m10 m11 m12 m13
m20 m21 m22 m23
m30 m31 m32 m33

you should obtain something like
m00 m02 m01 m03
m20 m22 m21 m23
m10 m12 m11 m13
m30 m31 m32 m33

this (check the sign!) should work fine!

Hope this helps.

Regards, Riccardo.

[CTZn]

Quaternions now ? Euler-angles ?!? Passionating ... hips !



Seriously what are the fourth line and column for ?

bkircher, if you think you can solve it by yourself and with rgigante hint (thanks for that), fine then. Else what I'll do my best to assist you. I have a good mind in general, but I have a real complex with maths...

[Kram1032]

three points of a tri and one more point, marking a line, that starts from the midpoint of the tri - the normal

[CTZn]

Is that for sure Kram ? I don't think that's that simple...

[Kram1032]

Should be so, yes... usually...
no guaranty, though (I neither use Maya nor XSI)

Maybe, that helps?
http://en.wikipedia.org/wiki/Rotation_matrix

[bkircher]

@ rgigante:
thanks for the info, well look into that eventually (taking each rotation by itself (CTZn found out the correct z.rotation already), and then we'll check the rotation order:

Swapping the vectors cross-wise seems to be a good idea.
Our transform matrix in Maya is a combination of scale, rotate and translate, so we would have to sort that piece by piece, i guess.

[rgigante]

@bkircher
u welcome, and yes swapping index will result in having all the transformations (transl, rot, scal, skew.. and so on) directly obtained.

Riccardo.

[CTZn]

three points of a tri and one more point, marking a line, that starts from the midpoint of the tri - the normal

I saw nothing like that in http://en.wikipedia.org/wiki/Rotation_matrix... We (well, they actually. I put z up by chance, could have been any other axis or none at all) are not dealing with geometry definition here.

[Kram1032]

hum...
yeah...
I'm not sure, anymore
I said stuff about the geometry, not about the rotation

[OnoSendai]

Added a section to the original post: "Getting the Indigo Directory Path"

[SmartDen]

i think, the thread needs to be updated, Ono

[OnoSendai]

Yes, you're right.
Anything you would like to see?
I've updated it with a couple more sections at the bottom.

[SmartDen]

i would like to see command line options and render settings that have no effect, e.g. image_save_period

[galinette]

Seriously what are the fourth line and column for ?

Homogeneous coordinates. An application of a math object known as "projective spaces". Hyper-useful for rasterized 3D.

For making it short, it generalizes the transformation matrix to translations, frustum projections, etc... using a 4x4 matrix. You can combine all the transformations (rotaton, scaling, skew, translation, perspective, etc...) just by multiplying 4x4 matrices, and with the resulting 4x4 matrix you have a transformation that will change object-local vertex coordinates into screen space coordinates in one matrix-vector multiplication. Isn't that magic?

[Headroom]

Mathemagic ;o)

Ah....well that little word play works better in German.