Ray Tracing?

Ray Tracing?

Post by Bernhard Jenn » Fri, 27 Aug 1999 04:00:00



Just a stupid question:
Can OpenGL do Ray Tracing?
 
 
 

Ray Tracing?

Post by Michael J. Sherma » Fri, 27 Aug 1999 04:00:00


Quote:> Just a stupid question:
> Can OpenGL do Ray Tracing?

Nope.  It's an interactive graphics
format.  Immediate mode kind of prevents
any sort of ray tracing or ray casting
rendering, but you can do enough tricks
to make it look cool (like using
OpenGL lights to mimic radiosity; that's
cool stuff!).

-Mike

--

--- Digital Sandbox, Inc. -------- (703) 464-5530 ---
"Back off man, I'm a scientist." -Peter, Ghostbusters

 
 
 

Ray Tracing?

Post by Bimo » Fri, 27 Aug 1999 04:00:00



Quote:> Just a stupid question:
> Can OpenGL do Ray Tracing?

No
Basicly it can only do the rendering, with additions like stencils, light
and tesselation... etc...
Still pretty fancy tho...

The math for raytracing is extensive.... far to extensive for even a high
end PC, so even with OpenGL, you would end up with a single frame every 20
minutes...
19.99999 minutes to calculate the frame
0.00001 minutes for OpenGL to draw it

So there would be no speed increase in using OpenGL for raytracing, you
could just as well use the WinAPI SetPixel (orwhateveritsnameis), and you
wouldnt see any difference..

IMO ofcause ;)

Lars

 
 
 

Ray Tracing?

Post by Paul Mart » Fri, 27 Aug 1999 04:00:00



>Just a stupid question:
>Can OpenGL do Ray Tracing?

OpenGL contains no direct support for raytracing.

You might want to use raytracing to produce realistic shadows and
reflections. There are many ways to simulate these effects in OpenGL without
raytracing.

OpenGL can be used as part of the ray intersection test. For example, the
scene can be rendered from the viewpoint, with a unique color assigned to
each primitive in the scene. This color can be read back to determine the
primitive intersected by a ray at a given pixel. If the exact geometry is
used in this algorithm, some aliasing may result. To reduce these aliasing
artifacts, bounding volumes could be rendered instead.

By changing the viewpoint and view direction, this algorithm can be used for
intersection testing of secondary rays as well.

A ray tracing application might also use OpenGL for display of the final
image. In this case, the application would be responsible for computing the
color value of each pixel. The pixels can then be rendered as individual
GL_POINTS primitives, or stored in an array and displayed via a call to
glDrawPixels().

   -Paul Martz
    Hewlett Packard Workstation Systems Lab
    To reply, remove "DONTSPAM" from email address.

 
 
 

Ray Tracing?

Post by Gareth Richard » Fri, 27 Aug 1999 04:00:00


There is no OpenGL function for raytracing. Any lighting done is per-vertex,
and objects don't reflect light. Simple, yet effective and efficient.

However, you could use textures on every object, and then do your own
raytracing/raycastig computations. Each texture would represent the lighting
effect on your objects. Of course, it wouldn't be dynamic, but then again,
neither is raytracing.

I've used it myself to implement correct shadows on objects, but it isn't
dynamic.


Quote:> Just a stupid question:
> Can OpenGL do Ray Tracing?

 
 
 

Ray Tracing?

Post by Gareth Richard » Fri, 27 Aug 1999 04:00:00





> > Just a stupid question:
> > Can OpenGL do Ray Tracing?

> No
> Basicly it can only do the rendering, with additions like stencils, light
> and tesselation... etc...
> Still pretty fancy tho...

> The math for raytracing is extensive.... far to extensive for even a high
> end PC, so even with OpenGL, you would end up with a single frame every 20
> minutes...
> 19.99999 minutes to calculate the frame
> 0.00001 minutes for OpenGL to draw it

So you regurlarly get 1666.6 fps do you?
(Forget Quake3 over the Internet, now THAT's lag)

btw - Only kidding.

- Show quoted text -

Quote:> So there would be no speed increase in using OpenGL for raytracing, you
> could just as well use the WinAPI SetPixel (orwhateveritsnameis), and you
> wouldnt see any difference..

> IMO ofcause ;)

> Lars

 
 
 

1. ANNOUNCE(POV-Ray): Ray tracing of trimmed rational surfaces

 Hello,

  I would like to announce new unofficial version of POV-Ray 3.02. This version
extends latest POV-Ray by ability of ray tracing trimmed rational (bezier)
surface patches. In addition it renders current "bicubic_patch" nearly at same
speed as method from official POV-Ray 3.02 but it does not require big ammount
of precomputed data. You can download source code of this patch from:

     ftp://atrey.karlin.mff.cuni.cz/pub/local/0rfelyus/povray-3.02/

  There are also binaries for Linux and MS DOS(compiled with DJGPP v2). Please
send me your comments, advices or reminders. Also I would like to see beautiful
pictures which you render with this version.

Dan

ps: if you are interested in algorithm I use than look at: Tomoyuki Nishita,
Thomas W. Sederberg and Masanori Kakimoro: Ray Tracing Trimmed Ratinnal Surface
Patches [proceedengs of SIGGRAPH '90; Computer Graphics, vol 24, Num 4, August
1990]

2. alpha color problems

3. POV-Ray and volume ray tracing?

4. Paint Shop Pro vs. Picture It

5. Moray bundled with Ray Tracing Worlds with POV-Ray

6. FS: 3DS4, Animator Pro, Inside 3DS....Now Reduced!!

7. FS: BOOK - Ray Tracing Worlds with POV-RAY (book+disks)

8. manipulating bmp files in a database

9. Ray-z-Buffer Approach for Ray Tracing

10. Ray tracing: ray-object intersection

11. Ray-tracing using non linear ray...

12. Fastest way to generate eye rays in Ray Tracing

13. ANNOUNCE(POV-Ray): Ray tracing of trimmed rational surfaces