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From: jonas-y@isy.liu.se (Jonas Yngvesson)
Newsgroups: comp.graphics,comp.graphics.visualization
Subject: Re: Any interest in a parallel raytracer?
Keywords: Parallel Raytracers
Message-ID: <1990Nov29.212143.2620@isy.liu.se>
Date: 29 Nov 90 21:21:43 GMT
References: <105@avatar.avatar.com>
Organization: Dept of EE, University of Linkoping
Lines: 81

kory@avatar.avatar.com (Kory Hamzeh) writes:

>I wrote a parallel raytracer (named 'prt') a while back with the following 
>features:

I have made a network distributed version of David K. Buck's
ray-tracer DKB. 

>	- Runs on multiple heterogeneous machines networked together
>	  using TCP/IP.

Same here, I used inetd to fire up a trace server on request from the
client. The client tokenizes the input file and sends these tokens to
each server. The client then distributes the job, one scanline per server
until the image is finished.

>	- Crude load balancing.
>	- Primitives:
>		- Polygons
>		- Spheres
>		- Hallow Sphere
>		- Cones
>		- Cylinders
>		- A object that can be expressed in a quadratic form
>		- Rings
>	- Shading:
>		- Gourard
>		- Phong
>		- Whitted
>	- Rendering:
>		- Simple: one ray per pixel
>		- Stochastic sampling (jitter)
>	- Instances of objects.
>	- Input format:
>		- An extention of nff. I have written a filter which
>		  will convert NFF files to prt format.

DDKB (distributed dkb) has the same primitives, shading and input
format as DKB (for obvious reasons). This includes very nice support
for solid texturing.

Antialiasing differs slightly. DKB uses an adaptive jittered
supersampling, but in DDKB, each server only has access to one scanline
at a time. This means adaption is done in x-direction only.

>	- Output format:
>		- MTV format (24 bit).

Here I have used a mix between the MTV-format an the QRT-format used
in DKB. An MTV-header is followed by the scanlines in QRT-format.
Each line tagged with its line number (this is because the lines are
stored in the order they are finished by the servers and must be
sorted before display).

>Note that prt is a parallel raytracer which spawns off children over
>multiple machines to distribute the work. I have only used it on five
>Sun Sparcstations and have gotten excellent performance. I'm not aware
>of any other public domain parallel raytracers other than VM_pRay 
>(which, I believe, runs only on a specific platform).

Yeah! We have tried DDKB running on 55 sparcstations (then we ran out
of file descriptors, perhaps we should use UDP instead of TCP).
Pretty good performance indeed.
Unfortunately DKB is not a terribly fast tracer in itself and I have no
time to hack around in it.

I'm not very willing so send this thing out though. Partly because it
is still only a hack, and partly because I have not contacted David
Buck and asked what he thinks about the whole thing.

--Jonas

------------------------------------------------------------------------------
 J o n a s   Y n g v e s s o n
Dept. of Electrical Engineering	                         jonas-y@isy.liu.se
University of Linkoping, Sweden                   ...!uunet!isy.liu.se!jonas-y
-- 
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 J o n a s   Y n g v e s s o n
Dept. of Electrical Engineering	                         jonas-y@isy.liu.se
University of Linkoping, Sweden                   ...!uunet!isy.liu.se!jonas-y