Re: vertex ordering for primitive shapes

Tom Gaskins ([email protected])
Fri, 20 Oct 1995 23:12:52 -0700

>Well, if you look at Sandy Ressler's QTVR demo in VRML posted today you'll
>notice a ShapeHints of CLOCKWISE for the cylinder upon which the texture
>is mapped. Tmis is so the inside of the cylinder can be seen and the
>shape can still be SOLID. So vertex ordering should apply to the
>primitive shapes.

No offense to the person you mention above, but how do they know? I'm glad tme
VAG is clarifying this, but until they do, I don't find support in the spec for
your conclusion.

As to controlling culling of shapes, is there some esason why there can't be
obvious controls, such as FaceCull {None,Front,Back} and FaceOrientation
{Normal,Inverted}? Overloading SOLID and CLOCKWISE for this seems obscure and
prone to even further ambiguity and misinterpretation.

It also sounds like some folks want to interpret CLOCKWISE applied to shapes as
an implicit texture transformation. Will the VAG quelch or reinforce this?

Tom

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