Guide For Exporter Writers

A forum for exporter development discussion.
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rgigante
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Post by rgigante » Sat Nov 03, 2007 9:54 pm

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.

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CTZn
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Post by CTZn » Sun Nov 04, 2007 1:19 am

:shock: Quaternions now ? Euler-angles ?!? Passionating ... hips ! :oops:

:arrow: :arrow:

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...
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Kram1032
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Post by Kram1032 » Sun Nov 04, 2007 4:43 am

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

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CTZn
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Post by CTZn » Sun Nov 04, 2007 4:59 am

Is that for sure Kram ? I don't think that's that simple...
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Kram1032
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Post by Kram1032 » Sun Nov 04, 2007 5:02 am

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
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Post by bkircher » Sun Nov 04, 2007 8:55 pm

@ 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.

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rgigante
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Post by rgigante » Sun Nov 04, 2007 10:11 pm

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

Riccardo.

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CTZn
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Post by CTZn » Mon Nov 05, 2007 2:59 am

kram wrote: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.
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Kram1032
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Post by Kram1032 » Mon Nov 05, 2007 4:10 am

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

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OnoSendai
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Re: Guide For Exporter Writers

Post by OnoSendai » Tue May 05, 2009 12:45 pm

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

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SmartDen
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Re: Guide For Exporter Writers

Post by SmartDen » Wed Jul 01, 2009 5:38 am

i think, the thread needs to be updated, Ono
Check normals, dude!

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Image

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OnoSendai
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Re: Guide For Exporter Writers

Post by OnoSendai » Wed Jul 01, 2009 5:55 pm

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

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SmartDen
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Re: Guide For Exporter Writers

Post by SmartDen » Wed Jul 01, 2009 7:38 pm

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

Image
Image

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galinette
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Re:

Post by galinette » Thu Jul 26, 2012 9:07 am

CTZn wrote: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?
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Headroom
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Guide For Exporter Writers

Post by Headroom » Thu Jul 26, 2012 10:43 am

Mathemagic ;o)

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