Hi!

I am currently developing a povray modeler for KDE (see 
http://www.azweb.de/kpovmodeler) and need some help with the projection 
types of the camera.

Currently I am only able to visualize the perspective and orthographic 
projections. I need some more detailed information on how the other 
projection types work. Can you point me to a web site or a book or... ? The 
user povray documentation says not much about these projections.

Greetings, Andreas

-- 
--------------------------------------------------
 Andreas Zehender, Dipl. Ing. (BA)
 Student, 9th semester computer science
 http://www.azweb.de
 az### [at] azwebde | zeh### [at] kdeorg      
--------------------------------------------------

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Have you checked the povray source? I think it's quite straightforward there.

-- 
#macro N(D,I)#if(I<6)cylinder{M()#local D[I]=div(D[I],104);M().5,2pigment{
rgb M()}}N(D,(D[I]>99?I:I+1))#end#end#macro M()<mod(D[I],13)-6,mod(div(D[I
],13),8)-3,10>#end blob{N(array[6]{11117333955,
7382340,3358,3900569407,970,4254934330},0)}//                     - Warp -

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Warp wrote:

>   Have you checked the povray source? I think it's quite straightforward
>   there.

Yes. I am looking at the render.c file at the moment. But a nice paper with 
some images would be nicer :-) 

-- 
--------------------------------------------------
 Andreas Zehender, Dipl. Ing. (BA)
 Student, 8th semester computer science
 http://www.azweb.de
 az### [at] azwebde | zeh### [at] kdeorg      
--------------------------------------------------

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Hmm, images could help explain the documentation a bit, also. I never really
understood how fisheye or omni cameras work.

- Slime
[ http://www.slimeland.com/ ]
[ http://www.slimeland.com/images/ ]

"Andreas Zehender" <zeh### [at] kdeorg> wrote in message
news:3be1a998$1@news.povray.org...
> Warp wrote:
>
> >   Have you checked the povray source? I think it's quite straightforward
> >   there.
>
> Yes. I am looking at the render.c file at the moment. But a nice paper
with
> some images would be nicer :-)
>
> --
> --------------------------------------------------
>  Andreas Zehender, Dipl. Ing. (BA)
>  Student, 8th semester computer science
>  http://www.azweb.de
>  az### [at] azwebde | zeh### [at] kdeorg
> --------------------------------------------------

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On Thu, 1 Nov 2001 20:16:44 +0100, Andreas Zehender <zeh### [at] kdeorg>
wrote:

>Currently I am only able to visualize the perspective and orthographic 
>projections. I need some more detailed information on how the other 
>projection types work. Can you point me to a web site or a book or... ? The 
>user povray documentation says not much about these projections.

You might have some trouble with the rest of the camera types in terms
of visualization, as I doubt Mesa supports real-time nonlinear
transformations :) 


Peter Popov ICQ : 15002700
Personal e-mail : pet### [at] vipbg
TAG      e-mail : pet### [at] tagpovrayorg

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Peter Popov wrote:

> You might have some trouble with the rest of the camera types in terms
> of visualization, as I doubt Mesa supports real-time nonlinear
> transformations :)

I know that.

Since I render only a wireframe, I will subdivide the rendered lines and do 
some vertex based non linear transformations (with some trigonometrical 
lookup tables for speedup) to approximate complex camera types.

I need no real time solution because the rendering is nonblocking and can 
take some time.

--
 Andreas Zehender, Dipl. Ing. (BA)
 Student, 8th semester computer science
 http://www.azweb.de
 az### [at] azwebde | zeh### [at] kdeorg

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> I know that.
>
> Since I render only a wireframe, I will subdivide the rendered lines and do
> some vertex based non linear transformations (with some trigonometrical
> lookup tables for speedup) to approximate complex camera types.

Are lookuptables still needed today for these usages ?
AFAIK first-person-shooters and thelike are using the FPU of the current
processors, so there shouldn't be the need to "accelerate" the program this
way....
(of course, these games are using mostly a perspective camera)

I think the times of precalculated Trig-tables are gone ...
BTW: What shall I do with my SupaDupa-Athlon with VeryFastKillThemAll-CPU ???
(I don't own an Alpha yet... ;)

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Jan Walzer wrote:

> Are lookuptables still needed today for these usages ?
> AFAIK first-person-shooters and thelike are using the FPU of the current
> processors, so there shouldn't be the need to "accelerate" the program
> this way....
> (of course, these games are using mostly a perspective camera)

I think so. You have much more vertexes than first person shooters in a 
modeler. Rendering the wireframe of the chess2.pov example takes half a 
second on my TNT 2 and a 433 celeron with a perspective camera.
And the perspective camera uses only simple transformations.

I think calling trigonometrical functions for each vertex would be far too 
slow (didn't tested it yet)

-- 
 Andreas Zehender, Dipl. Ing. (BA)
 Student, 9th semester computer science
 http://www.azweb.de
 az### [at] azwebde | zeh### [at] kdeorg

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"Andreas Zehender" <zeh### [at] kdeorg> schrieb im Newsbeitrag
news:3be7002e@news.povray.org...
> Jan Walzer wrote:
>
> > Are lookuptables still needed today for these usages ?
> > AFAIK first-person-shooters and thelike are using the FPU of the current
> > processors, so there shouldn't be the need to "accelerate" the program
> > this way....
> > (of course, these games are using mostly a perspective camera)
>
> I think so. You have much more vertexes than first person shooters in a
> modeler. Rendering the wireframe of the chess2.pov example takes half a
> second on my TNT 2 and a 433 celeron with a perspective camera.
> And the perspective camera uses only simple transformations.
>
> I think calling trigonometrical functions for each vertex would be far too
> slow (didn't tested it yet)


I think there are other optimizations to go before using tables ...
I can't really believe that the FPUs are still SOOOOO much slower ...
Consider, that for a modeller, you'll need a very high accuracy, and so you
need very big tables ...
Also I'm sure, you won't use Integer(or Fixpoint)-Maths ...
So you'll have to transfer your numbers from FPU to memory, and back often
enough ...
This won't speed up your program very much ...

I for myself, would leave this option open, as one of the last ways to speed
up, if it's still to slow ... (or make it optional)

You surely have already thought about backface culling and thelike, haven't
you ?


--
Jan Walzer <jan### [at] lzernet>

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