INVALID_ADDRESS wrote:

>Of course the outer border/circle of the rings must touch the triangle.
>But how large should these rings be?
>   1. The outer circles intersect at the triangle's midpoint
>      This is the easiest case: outer circle is as before; some linewidth
>      is added towards the circle's centers.
>   2. The inner circles intersect at the triangle's midpoint
>      I don't think this is looking good with a large linewidth, so
>      the calculation isn't worth it.
>   3. The "mid-circles" with radius=(inner_radius+outer_radius)/2 intersect
>      at the triangle's midpoint.
>      I suppose this will look "most gothic", but will require some
>      calculation ... (maybe I'll do this).

Yes, realistically the stone trifoil tracery would not be merely tangent to
a circle which frames it, but would look like it was being "blobbed" into
it. (Else, how could it the tracery be physically held in place?)
For instance, the hexafoils framing the stained glass in the upper part of
this image from Bourges Cathedral:
http://www.bc.edu/bc_org/avp/cas/fnart/arch/gothic/bourges/bourges_int09.jpg


>
>You should also try to remove the inner parts of the rings by difference-ing
>with a cylinder around Center, having a radius = Radius.

I didn't know if it really mattered exactly what sort of primitive was being
used to difference out the parts of the rings.  Would there be a benefit in
terms of tracing/parsing time?

>Next tasks :)
>   - replace the torii by cylindrical rings (difference of a cylinder and a
>     thinner, but slightly longer [to avois coincident surfaces] cylinder,
>     the Thickness being a new parameter). You have to do a little calculation
>     involving Linewidth (or LinewidthFactor or whatever), but then changing
>     this Linewidth is no pain: no new hand-calculation is neccessary, POV-Ray
>     does it all. I suggest to write a macro Ring ( Radius, Linewidth ) that
>     "behaves" similar to torus { Minor, Major ... }, this makes it easy to
>     change all torus{} objects to Ring objects. The trick of omitting the
>     closing "}" of the object created by Ring will help (look at the end
>     of the Trefoil macro where I used this trick).

I thought of this, but the edges looked a little too squared off for what I
remember being authentic (and I've been poring over A LOT of books &
websites about cathedrals & Gothic style).


>   - create your *own* stone texture

jaw drops, mouth goes dry, limbs gradually go numb... ;-)

>   - arrange some trefoils, light source(s) and a camera to create a pleasing
>     scene; perhaps add some bricks, columns, decorative elements, windows,
>     floor tiles, stone carvings, stairs, roof tiles, ...
>   - at least *try* to find a solution for "true gothic" case 3.
>
  The 2nd of these last two tasks seems to be the easier!
I have thus far a floor, columns & footings, empty windows waiting for
inspired "glass" (maybe just borrowed images converted to a format that
will allow me to play with the transparency/translucency).  I also have the
nave ceiling ribbing and vaulting, piers at the 'crossing', a west wall &
portal.  All of these are still quite primitive looking, but they're the
most my skills (and limited time to work ) allow.
I went thorough a lot of trouble to get the vault ribbing to look like it
was composed of individual component pieces (again, as in the image cited
above).
I'd post it on the images group as a WIP, but I'm still too embarrassed at
how little progress I've made, when I think of how long I've actually been
at it.

But then again, I really didn't spend a lot of time on spheres & checkered
planes before I dove in over my head.  Boring!

Thanks again for all your input!
--Mark

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