Christoph Hormann <chr### [at] gmxde> wrote in
news:2bd### [at] tritonimagicode: 

> Tor Olav Kristensen wrote:
>> 
>>>These all look very interesting, i wonder if this could be extended
>>>to a system to design shapes with smooth transits, with a few
>>>elements like this you could build a rounded version of any CSG made
>>>of axis-aligned boxes.
>> 
>> 
>> Good idea.
>> 
>> It should certainly be possible, but I'll have to think
>> about it for a while to find out how to do it.
> 
> Thinking a bit more about it: There are possible special cases where 
> things might get quite complicated - But it should not be too
> difficult to do for a difference between two boxes for example: check
> every corner 
>   of the second box if it is inside the first box and trace along all 
> edges.  This information should be enough to build the resulting
> shape. 

Yes I think that would work.

I don't know if this would easier to implement, but here's
what I thought of:

Divide space into cubes and only then allow each box to
occupy exactly one cube. Then let macros find out which
sides, edges and cornes need to be rendered. (If a box has
a neighboring box at one of their sides, then their common
side, edges and corners should not be rendered. It would
be more difficult to make rules for boxes that are neigh-
bours only at edges or corners.)


> The whole thing might be easier though if you start with a analytical 
> tesselation algorithm (approach would be similar as drafted above with
> insideness tests and traces) and then apply a subdivision algorithm
> and forget about bicubic patches (and if you are even lazier you
> forget about POV-SDL and model your shape in Wings3D :-)).


Hehe...

Yes, but I love solving geometric problems in POV-SDL =)

I have tried to force myself to not look into tesselation
algorithms and surface subdivision before I'm have studied
surface modelling with splines in greater detail.
(And that may take a while.)

Btw.: I suspect there to be strong relations between the
math used for tesselation and the math used when modelling
with splines.


Tor Olav

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