RE: polygon question

Steve Ghee (steve@division.co.uk)
Wed, 22 Nov 1995 09:15:39 -0000


Cindy writes:-
How about a format like...
Rotation {
Xrot Yrot Zrot priority deg/rad
}

Yukkk

butchering existing nodes like this is horrible; if axial rotations are =
required, then why not have a different node type, for example:-

Euler {
fields [SFVec3F rotation, SFEnum order, SFEnum units]
rotation 0 0 0
order ZXY
units DEGRESS
}

(these are, after all, Euler angles we are describing here!) The =
'order' field should default to some value (I suggsst =
ZXY=3Droll/pitch/yaw).

This would allow MUCH easier rotations about multiple axes and would be
much closer to the way most 3D modeling systems work.

Actually, many 3D systems use the vector/angle approach; Euler angles =
suffer from a number of problems including gimbal lock etc. The =
vector/angle (quaternion) approach is more stable and allows for correct =
interpolation (animation) between defined orientations.

Euler angles are typically useful when entering orientation by hand - it =
is (relatively) easy to figure out the sequence on paper etc. I would =
suggsst that any CAD converter can generate the vector/angle sequence, =
and should do.

------------------------------------
Steve Ghee email: steve@division.co.uk
Director of New Technolgy www: http://www.division.com
Division Ltd tel: [+44] 145 461 5554
19 Apex Court fax: {+44] 145 561 5532
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Almondsbury
Bristol BS12 4JT
UK.


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