> > but I can't understand your thinking that
> > tesselation as object modifier is dangerous
> > considering ideal tesselation - tesselated object has inside and
> > outside just like base object - than why it couldn't be part of csg ?
>
> Because I have applied (yes, now) the tesselation patch to
> a non-megapov version (my personal experimental 3.1),
> and within 3.1, mesh cannot be part of a CSG difference/intersection.

the main part of my plans is connected with features of 3.5 and
therefore I think always about features of megapov
but right - solid triangle mesh is part of "Meybe" of
http://www.povray.org/3.5-status.html

> As I do not have access to your patch, all I was able to do was
> guessing. Wrongly, I thought that to perform the twist/bend/screw,
> you had transformed the object (let's it be a CSG or blob) into a mesh.
> Then applying a transformation to the vertex of this mesh.

there is more about my idea in p.u-p in todays posts

> > (independant this means that they have something like pointer->method or
> > function(pointer) and this "method" only internal depends of type of object)
> > never mind if it is sphere, cylinder or isosurface
>
> > if you smart replace pointer (internal) to currently parsed object you can
make
> > it invisible
> > for that tesselated object is putted instead of original object
>
> Well, you may have to reallocate the instanced object structure because some
> object have bigger structure than other ones.
>
> That's why I do not like the idea of an object modifier which nearly
> substitute a structure for another.
>
> When the script start saying it want a Pizza, I like to end
> with a Pizza (even if you change the pepperoni for pineapple
> and the sweet pepper for some corn).

I don't want tesselate anything without agreement of user

> I do not like this confusing approach, even if I can both like
> Pizza and Sushi.

well written documentation should have description what deform{} cause

> > I play some years with pov
> > I don't like to be intruder in any community therefore since year I slowly
read
> > whole news.povray.org to understand meaning of life :-) and I never meet
opinion
> > that povsyntax should be mirror of internal structure. Perhaps I'm wrong but
I
> > never meet. It shouldn't go far from internal but if there is something to
> > simply understand with syntax different than internal structure why not ?
>
> This may be the start of a full chapter of holy war about the pov syntax,
> should it be object oriented or not, should it looks like C++ or some
> others language, and so on.

right

> I do not care, as I'm not in charge of defending the syntax.
> I would prefer to see your patch public, even done with a way I do not
> like , rather than nothing. Afterall, the povteam will be able
> to change it to the way they want if they ever find it too confusing
> or too complex or inadequate (or whatever).

right

> Warp are built-in the engine, so that's easy when evaluating the texture to
> apply a warp to it.

I plan support this built-in engine of warps

> > - therefore I changed syntax to object modifiers but
> > internals it is still another kind of object - it is just easier method to
do it
> > for me becouse it has different method all_intersections()
>
> I think you should not have listen to the advisers, it would have make
> me happier :-)

perhaps :-)
but I play with this syntax
and it is just simpler to me

> > I've not finished it yet and I don't want publish not finished code only to
> > proof something.
>
> Good, but I would very like to see how you resolve the problem
> of the shadow and reflection (transforming an object only for the camera,
> I can do it, but my headache starts when I start thinking about
> the reflected ray and the lights ray...).

I must finish my opened functions and than I prepare some images to p.b.i
I think it will be ready to send after weekend

> > Although I don't think that I did miracle.
>
> Well, the twist/bend/screw thing is resisting many pov-programmers, including
> me recently...

Well, currently I play with pure mechanism of inheriting of textures
You can halp me with type of deformations
every deformations should have described four things
b) undeform function
a) deform function (with calculation of new normal)
c) calculation of new bbox of deformed bbox
d) calculations of begining and ending of ray crossing deformed shape (for
twisting it is cylinder)

> > Whole
> > method was descibed here, in p.u-p with symbolic algorithm.
>
> I found the thread, but did not see the symbolic algorithm.
> Can you provide the reference of the message, thanks.

Here is symbolic notation of my all_intersections method:

take depth1 and depth2 for container or bounding box
take function deform and undeform (opposite to deform)
for i=depth1 to depth2 step accuracy
  point1=evaluate_ray(trace_ray,i)
  point2=evaluate_ray(trace_ray,i+accuracy)
  pointA=undeform(point1)
  pointB=undeform(point2)
  deformed_ray=create_ray_beetwen(pointA,pointB)
  all_intersections(deformed_ray,base_object)
  for every intersection beetween pointA and pointB
    get deformed intersection and deformed normal with deform(intersection)
    if it is beetween pointA and pointB than put it on stack
  end for
end for

> > I don't think that my method is best way - it has limitations (reversable
> > deformations) and it has something like accuracy (like isosurfaces) but it
works
> > for all objects, not only for meshes.
>
> I'm curious... I will have to wait...

after advice of Chris Huff I plan to omit this limitations

> Now, the tesselate patch introduce an interesting approach.
> Applying a mesh-deform patch using warp definition
> as mesh modifier to a tesselated
> object allow get all the warp being available to play
> with all objects that can be tesselated.

please read about my plans in "torus torture" thread in p.b.a or p.u.p

> > > But I cannot still understand
> > > how you can apply them into the resolving intersection of a line
> > > and a sphere (e.g. as is currently the function for the sphere object)
> > > when applied to a true basic object (and not a set of triangles)
> >
> > by spliting ray to short segments and deform them and intersect base object
>
> Ouch...

sorry, what's wrong ? :-)

> > http://www.abx.art.pl/pov/nonlinear/step3.jpg
>
> Nice!!!
> I can imagine how to do it with a warp-based mesh deformation,
> but you probably did it with a real checkered box.

right, with uv-mapping

> I was wrong,
> But may I ask to have some background checkered planes and some
> shadows of the box casted on them. I'm really curious.

as I said I'll prepare some images for you

> > is there any other person who can vote against or opposite for:
> > a) deform as part of object modifiers
> > b) tesselate as part of object modifiers
> > it is not oblique voting for authors of patches but let's disscuse
> >
> > ABX
>
> May I ask who care ?

if there is no difference for me where I put definition of patch
than I want do something for community - where they want

> IMO, do your patch your way, then let people comment them and use them.
> I prefer to have a lot of patches than none... as long
> as you do not break everything...

ok. here is current list of closed modifications

new module deform.c with definition of Deform object
new Parse_Deform() in parse.c
new closing parts of functions called Parse_Object_Mod()
new CASE in Parse_Object_Mod()
some new tokens
new field in ISTACK
new parameter to all All_Intersections with max_depth

Best regards,

ABX

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