Re:Geometric primitives

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Re:Geometric primitives

David Faught
Howard Stearns wrote:
>That's a reasonable default for "primitives", but certainly not
>for every primitive, nor every object. (What does the user
>consider primitive?)

I'm talking specifically about geometric solid primitives.  I don't know that users should consider anything at all about primitives, but it's a pretty clear cut thing for developers.  For geometric solid primitives, the developer only specifies the shape and size.  For example, a sphere of diameter 2 units.  For a non-primitive geometric object, such as a TMesh, the individual vertices and their positions are specified more or less directly by the developer.

>For example, current layout algorithms rarely consider any
>arrangement of text to be centered about a 0,0,0 origin, nor many
>"alignment" primitives. And consider where the business end of a
>"pencil" or "turtle" primitive should be. As I understand it,
>VRML doesn't consider such stuff.

You're right.  I am not really generalizing to include those types of things, although I do think it's reasonable for them to have a standardized default position and orientation in the world before any transformations are applied to them.

And I would caution against dealing with the business end of an uncivilized turtle in any case.

>That said, I think of TCylinder and TSphere as quick placeholders
>that would benefit from some more thought. Not a priority that
>I'm aware of.

That is the whole point of the geometric solid primitives as I understand it.  They are quick shorthand methods of generating some common shapes and nothing more.

>On Apr 27, 2006, at 8:14 AM, David Faught wrote:
>>Should Croquet's geometric primitives, like TCube and TSphere,
>>be centered on the origin prior to any transformation?