Yep, nice history lesson Ken. I know all about that stuff. I've used POV
1.0 and basically started with POV 2.0. Had a 486 33SX w. 8 megs ram.
High speed rendering, watching pixels draw across the screen.
I just used the words "half infinite" to describe a plane earlier this
weekend too. Not exactly the best terminology. They are probably best
thought of as enormous boxes which can reach to the edges of a pov scene
in 5 directions, although they can still be stood upon on the 6th
surface if you are a pov object. How's that?
The all time best explanation of such things to me has always been
seeing those kinds of things like that 6 plane box primitive.


Ken wrote:
> 
> Bob Hughes wrote:
> 
> > To get openings into planes you have to use 'clipped_by' instead of
> > difference since the plane is considered infinitely deep and no box
> > could ever difference all the way through.
> 
> Historical Point of Order:
> 
>    A minor correction to your staement concerning planes being treated as
> infinetly deep. If you construct a box using a csg of 6 planes and have
> their normals correctly oriented then there is no issue of infinite
> depth. The interior of the csg construct will become the bounding limits
> of the plane objects. This is evidenced by the way a clipped by shows
> only a shell of the clipped object when so treated rather than a true
> solid object as you would expect.
>   Something that many users are not aware too is that the box object
> is really nothing more than an internaly constructed object using
> a cgs of 6 plane objects. Originaly when Pov grew from DKBTrace the
> box object was used by way of the original shapes.inc file. They
> thought is wise in later versions to instead make these declared
> objects primitaves internal to the program rather than through the
> repeated use of predeclared declared shapes accessed through the use
> of include files. The memory hit was substantualy less and this was
> a major issue as most users had at most 1 - 4 megs of memory on their
> systems at that time. A 386 with 8 megs of ram was considered
> a very well equipped system and those who owned systems with 16 megs
> were gods amoung the rest.
>    Take a look a the file shapes.old for methods of creating most of
> the common predefined primitaves using spheres, planes, quartics,
> and quadrics. Things have been simplified since the early days but
> you can still find evidence of these older times if you look hard
> enough.
> 
> --
> Ken Tyler
> 
> mailto://tylereng@pacbell.net

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