sorry if the list is known
here is summary how my lately reports (and confirmations) work with RC4

POV 3.5 RC4 icl on WinNT Sp 6 PII 233 with 128 MB

crash

  return local: news.povray.org/e3piut8anmf4cli4pnfmstadgc3nleqvb2@4ax.com

not works as (I) expected

  splines:      news.povray.org/m4f7cug9ch19jbve8m8prf4vl8ima0rsma@4ax.com
                when point is added then type of spline is overwritten
                so bottom, second from right is wrong
  bounding:     news.povray.org/2g0dcu8kasg84pqde8hdq9d60nkoa1cvka@4ax.com
                sphere-sweeps are still clipped
  evaluate msg: news.povray.org/4nhfduk9gon9m76s6f6vu3k8gsjf7rrdjp@4ax.com
                end of paragraph makes suggested value of evaluate valid
                for report of next evaluate

ABX

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> sorry if the list is known
> here is summary how my lately reports (and confirmations) work with
> RC4
> 
> POV 3.5 RC4 icl on WinNT Sp 6 PII 233 with 128 MB
> 
> crash
> 
>   return local:
>   news.povray.org/e3piut8anmf4cli4pnfmstadgc3nleqvb2@4ax.com
> 
> not works as (I) expected
> 
>   splines:     
>   news.povray.org/m4f7cug9ch19jbve8m8prf4vl8ima0rsma@4ax.com
>                 when point is added then type of spline is overwritten
>                 so bottom, second from right is wrong
>   bounding:    
>   news.povray.org/2g0dcu8kasg84pqde8hdq9d60nkoa1cvka@4ax.com
>                 sphere-sweeps are still clipped
>   evaluate msg:
>   news.povray.org/4nhfduk9gon9m76s6f6vu3k8gsjf7rrdjp@4ax.com
>                 end of paragraph makes suggested value of evaluate
>                 valid for report of next evaluate

Does any of these bugs still need confirmation?
Could you please give full http:// links in future? My newsreader can't 
open them directly because it thinks it's a mail address or MID.
-- 
Felix Wiemann

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On Wed, 08 May 2002 20:11:17 +0200, Felix Wiemann <Fel### [at] gmxnet>
wrote:
> Does any of these bugs still need confirmation?

I think non of "not works as expected" was here confirmed hovewer. Crash was
confirmed by Chris Hormann.

> Could you please give full http:// links in future? My newsreader can't 
> open them directly because it thinks it's a mail address or MID.

It is Messege ID! It works fine with both prefixes news:// and http://
Usually I add http:// hovewer this time I removed it intentionally becouse of
idea of justification.

ABX

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> It is Messege ID! It works fine with both prefixes news:// and http://
> Usually I add http:// hovewer this time I removed it intentionally
> becouse of idea of justification.

Sorry, I didn't notice that. Maybe it's better if the news.povray.org/ 
in front of the message ID is removed. Or it's my newsreader's fault. I 
don't know.
-- 
Felix Wiemann

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Skiba <abx### [at] babilonorg>  wrote:

>   splines:      news.povray.org/m4f7cug9ch19jbve8m8prf4vl8ima0rsma@4ax.com
>                 when point is added then type of spline is overwritten
>                 so bottom, second from right is wrong

I don't get what you want to say in the sentence above.

>   bounding:     news.povray.org/2g0dcu8kasg84pqde8hdq9d60nkoa1cvka@4ax.com
>                 sphere-sweeps are still clipped

Yes, and this will remain the way it is unless someone comes up with code to
determine the bounding box of a Catmull-Rom spline segment.  It turns out the
original sphere_sweep code simply adds a bit to the control point bounding
box.  The problem appears only for Catmull-Rom splines because they may exceed
their control points which the code uses to find the bounding...

>   evaluate msg: news.povray.org/4nhfduk9gon9m76s6f6vu3k8gsjf7rrdjp@4ax.com
>                 end of paragraph makes suggested value of evaluate valid
>                 for report of next evaluate

I don't get what is supposed to be wrong here?!?

    Thorsten

____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde

Visit POV-Ray on the web: http://mac.povray.org

Post a reply to this message

On Thu, 09 May 2002 11:56:33 +0200, "Thorsten Froehlich" <tho### [at] trfde>
wrote:
> >   splines:      news.povray.org/m4f7cug9ch19jbve8m8prf4vl8ima0rsma@4ax.com
> >                 when point is added then type of spline is overwritten
> >                 so bottom, second from right is wrong
>
> I don't get what you want to say in the sentence above.

Sorry if it is caused by me English. I try to write it again and show shorter
example: when I copy spline identifier and add point in the same time then I
expect that new spline will have the same type and new point. Point is added
but type of spline is overwritten. Example:

  #macro Draw(Spline,Color)
    #local c=0;
    #while (c<1)
      sphere{Spline(c) .1 translate 3*z pigment{Color} finish{ambient 1}}
      #local c=c+.01;
    #end
  #end
  background{1}
  #local S=spline{ cubic_spline -1 5*x 0 x 1 y 2 5*y }
  Draw(S,red 1)
  Draw(spline{S 0.5 x+y},blue 1)

> >   bounding:     news.povray.org/2g0dcu8kasg84pqde8hdq9d60nkoa1cvka@4ax.com
>
> Yes, and this will remain the way it is unless someone comes up with code

I see.

> >   evaluate msg: news.povray.org/4nhfduk9gon9m76s6f6vu3k8gsjf7rrdjp@4ax.com
> >                 end of paragraph makes suggested value of evaluate valid
> >                 for report of next evaluate
>
> I don't get what is supposed to be wrong here?!?

Nothing is wrong. The problem is that it is just less readable when suggested
values are connected in this paragraph with evaluated values of next evaluate.
Just problem of place of "\n" placing. But if it is caused by internall
wraping system for all messages then probably nothing to worry about - values
are (I suppose) correct.

ABX

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"Thorsten Froehlich" <tho### [at] trfde> wrote in message
news:3cda47d8@news.povray.org...
> Yes, and this will remain the way it is unless someone comes up with code
to
> determine the bounding box of a Catmull-Rom spline segment.  It turns out
the
> original sphere_sweep code simply adds a bit to the control point bounding
> box.  The problem appears only for Catmull-Rom splines because they may
exceed
> their control points which the code uses to find the bounding...

If there is already code for the bounding box of a Bezier spline segment,
is it difficult to internally convert Catmull-Rom spline segment into Bezier
one
(to find the two additional control points) and to use it?

Gleb

Post a reply to this message

In article <3cda78bf$1@news.povray.org> , "Gleb" <gk1### [at] sotonacuk> wrote:

> If there is already code for the bounding box of a Bezier spline segment,

In case you did not notice, we are talking about too tight bounding here.  So
this is not the question.  All sphere_sweeps are bounded for speed reasons -
and you don't want to render any sphere_sweep without bounding!

> is it difficult to internally convert Catmull-Rom spline segment into Bezier
> one (to find the two additional control points) and to use it?

A Catmull-Rom spline can extend "beyond" its control points.  It is not a
matter of converting to some other spline type.  The problem is to determine
the bounds of a Catmull-Rom spline segment by just looking at the control
points, which is simply not possible due to the nature of this spline type.

To clarify my original point:

This is not going to be fixed because nobody in the team has the time to look
into this mess.  Making wild suggestions won't help ;-)

Only plain and simple source code, based on the available sphere_sweep code
that can be found in MegaPOV, if contributed by someone _soon_, will fix the
problem in the initial 3.5 release.  The code was already been broken in the
original patch :-(  Its author apparently did not know a good way how to fix
it either, so don't expect magic from us!

    Thorsten

____________________________________________________
Thorsten Froehlich
e-mail: mac### [at] povrayorg

I am a member of the POV-Ray Team.
Visit POV-Ray on the web: http://mac.povray.org

Post a reply to this message

Thorsten Froehlich wrote:
> In case you did not notice, we are talking about
> too tight bounding here.  So this is not the question.

Perhaps he did notice and perhaps he has a valid point. You are always
very quick to reject other people's suggestions as being nonsense or
irrelevant.

Anyway, please see my post in povray.beta-test.binaries for a suggestion
for bounding which is inspired my Gleb's message.

Rune
--
3D images and anims, include files, tutorials and more:
Rune's World:  http://rsj.mobilixnet.dk (updated Apr 14)
POV-Ray Users: http://rsj.mobilixnet.dk/povrayusers/
POV-Ray Ring:  http://webring.povray.co.uk

Post a reply to this message

Thorsten Froehlich wrote:
> 

> Skiba <abx### [at] babilonorg>  wrote:
> 
> >   splines:      news.povray.org/m4f7cug9ch19jbve8m8prf4vl8ima0rsma@4ax.com
> >                 when point is added then type of spline is overwritten
> >                 so bottom, second from right is wrong
> 
> I don't get what you want to say in the sentence above.
> 
> >   bounding:     news.povray.org/2g0dcu8kasg84pqde8hdq9d60nkoa1cvka@4ax.com
> >                 sphere-sweeps are still clipped
> 
> Yes, and this will remain the way it is unless someone comes up with code to
> determine the bounding box of a Catmull-Rom spline segment.  It turns out the
> original sphere_sweep code simply adds a bit to the control point bounding
> box.  The problem appears only for Catmull-Rom splines because they may exceed
> their control points which the code uses to find the bounding...

I have not looked very closely at this, but I don't
think it that it should be very difficult to find an
analytical solution to this.

As I understand it, there should be 3 cubic polynomials
that controls the x, y and z components for each segment.

Just differentiate these (to quadratic polynomials) and
solve for zero to find the max and min points of the
cubic polynomials. The values of the cubic polynomials
at these points will give the components for the
bounding box.

If any of the cubic polynomials has no real roots, then
I think that values at the endpoints of the cubic will
polynomials give the max and min points for the spline
segment.


Tor Olav

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