Hi,
   You might want to read my question on povray.advanced-users 
concerning my trace scanning script.

The first image is the trace scan of a sphere { 0, 1}.
The second on is the trace scane of a torus { 0.7, 0.3 rotate x*90 }

Images were parsed by povray with my trace scan script, and were 
rendered by a home made OpenGL application.

The bug is that the sphere and the torus are strangely scaled; normally 
you should get a bunch of circles made of the dots, now you get an egg 
shape...

Where does the egg shape comes from??

Here is my TraceRay function; for a given XZ point it gets all the Y 
values were it hits a surface of my object.

#declare StartRay = <X,2,Y>;
#declare SurfaceTouch = StartRay;
#while(StartRay.y > -1)
   #declare SurfaceTouch = trace(MyObject, StartRay, <X, -2, Y>);

   #if(SurfaceTouch.x != 0 | SurfaceTouch.y != 0 | SurfaceTouch.z != 0)
     #write(myFile str(SurfaceTouch.y, 0,3), " ")
   #else
     #declare SurfaceTouch = <0,-2,0>;
   #end

   #declare StartRay = SurfaceTouch;
#end

Thanks a lot for any help!
   Xilo

-- 
Dedicated to audio/visual and interactive artwork.
Author of The Primary Colors of CSound:
http://www.geocities.com/simonlemieux/PCCS/index.html

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Attachments:
Download 'sphere-gl.jpg' (31 KB) Download 'torus-gl.jpg' (23 KB)

Preview of image 'sphere-gl.jpg'

Preview of image 'torus-gl.jpg'

Xilo Musimene wrote:
> 
> [...]
> 
> #declare StartRay = <X,2,Y>;
> #declare SurfaceTouch = StartRay;
> #while(StartRay.y > -1)
>    #declare SurfaceTouch = trace(MyObject, StartRay, <X, -2, Y>);
> 
>    #if(SurfaceTouch.x != 0 | SurfaceTouch.y != 0 | SurfaceTouch.z != 0)
>      #write(myFile str(SurfaceTouch.y, 0,3), " ")

Just read the manual.  Apart from that it would also be advisable to check
what the trace function actually returns before jumping to quick
conclusions about bugs.  If you did that you would see that all points
returned by a successful trace (which is tested differently than you do in
your code) are perfectly on the object surface.

I think we should introduce a new rule: everyone who falsely assumes there
is a bug in POV-Ray has to do something unpleasant (like 10 times
rendering the POV-Ray benchmark or so...)

Christoph

-- 
POV-Ray tutorials, include files, Sim-POV,
HCR-Edit and more: http://www.tu-bs.de/~y0013390/
Last updated 28 Feb. 2003 _____./\/^>_*_<^\/\.______

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> Just read the manual.  Apart from that it would also be advisable to check
> what the trace function actually returns before jumping to quick
> conclusions about bugs.  If you did that you would see that all points
> returned by a successful trace (which is tested differently than you do in
> your code) are perfectly on the object surface.
> 
> I think we should introduce a new rule: everyone who falsely assumes there
> is a bug in POV-Ray has to do something unpleasant (like 10 times
> rendering the POV-Ray benchmark or so...)

Well, I was just looking to know if that was a known problem of the 
trace function, but if you tell me the trace function is not responsible 
for the bug, then it is my code and it answers my question!

Thank you!
   Xilo

-- 
Dedicated to audio/visual and interactive artwork.
Author of The Primary Colors of CSound:
http://www.geocities.com/simonlemieux/PCCS/index.html

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> I think we should introduce a new rule: everyone who falsely assumes there
> is a bug in POV-Ray has to do something unpleasant (like 10 times
> rendering the POV-Ray benchmark or so...)
>
> Christoph

but this is a good way to attract somebody attention

isn't is?

Bruno Gimeno
esto es la realidad
http://usuarios.tripod.es/game2413

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> but this is a good way to attract somebody attention

I'm not sure what you exactly  mean Bruno, but I was only trying to 
catch attention to a problem I had with advanced-user stuff...  A 
problem that *might* have been a bug...  Actually it Was a bug, but not 
in the trace function...  So the question at first still is correct (see 
subject of thread!)

Xilo

-- 
Dedicated to audio/visual and interactive artwork.
Author of The Primary Colors of CSound:
http://www.geocities.com/simonlemieux/PCCS/index.html

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Xilo Musimene wrote:

>The first image is the trace scan of a sphere { 0, 1}.
>The second on is the trace scane of a torus { 0.7, 0.3 rotate x*90 }

this sounds like a POV2CNC comming up...

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> this sounds like a POV2CNC comming up...

What is CNC?
Does pov2cnc already exists?

Thanks,
   Xilo

-- 
Dedicated to audio/visual and interactive artwork.
Author of The Primary Colors of CSound:
http://www.geocities.com/simonlemieux/PCCS/index.html

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