Ken <tyl### [at] pacbellnet> writes:

> I could have sworn the Pov-Ray docs explicitly state that
> the left handed system is used by default contrary to what
> the rest of the world uses. I'm may be getting old buy my
> memory isn't that bad.



                                          Section 4.1.1
                           Understanding POV-Ray's Coordinate System

First, we have to tell POV-Ray where our camera is and where it is
looking. To do this, we use 3D coordinates. The usual coordinate system for
POV-Ray has the positive y-axis pointing up, the positive x-axis pointing
to the right, and the positive z-axis pointing into the screen as follows:

[Here is a picture of a left-handedly *displayed* coordinate system]

Section 7.4.4.5.2
                                          Handedness

The right vector also describes the direction to the right of the
camera. It tells POV-Ray where the right side of your screen is. The sign
of the right vector can be used to determine the handedness of the
coordinate system in use. The default right statement is:

  right <1.33, 0, 0>

[So the handedness described here is only the one of the camera, as stated
above.]

  I confirm my position.  The handedness of a coordinate system is given by
the way it calculates cross-products, not by the way it looks because it
has no canonical way to look.  A coordinate system is abstract, and if you
want to make it look like something you have to choose a camera
orientation.  This does not change the handedness of the space.  And
POV-Ray uses a right-handed cross-product.  The default *camera* is
left-handed, that's all.

  Other suggestions?

Roland.
-- 
Les francophones m'appellent Roland Mas,
English speakers call me Rowlannd' Mass,
Nihongode hanasu hitoha [Lolando Masu] to iimasu.
Choisissez ! Take your pick ! Erande kudasai !

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