Subject: graphics demo

From: Bernie Roehl <broehl>
Date: Tue, 25 Feb 92 13:54:08 EST

> From: Chris Hand <[email-masked]>
> If you haven't seen it already, I'd suggest
> you download a copy of the "ultraforce vector
> demo" (?) from saffron.inset.com or elsewhere.
> It's called vectdemo.zip

I've put a copy of this on sunee, in the pub/vr directory.
(The site saffron.inset.com doesn't allow daytime access to its
archives, and the only other place I could find it was a site in
Australia; hopefully having it on sunee will make it a little more
accessible).

> Has anyone seen this demo?  Will REND386 be faster?

Yes, and yes.  The vectdemo is certainly spiffy; I like their metallic
shading effect.  It's actually quite simple to do in 256-color mode;
if you pause the demo (using the backspace key) and look closely, you'll
see that every scanline within a poly is the same color.  They basically
cycle through a set of metallic colors on consecutive poly scan lines,
the cycling being influenced by the angle of the polygon.  Neat effect,
and cheap to implement too; we may put this into REND386 when we switch
to 256-color mode.

The "reflections" on the surface of the "water" are just the images above,
sampled every so many scanlines to give a compressive effect; I see this
as a frill, though it does enhance the overall look.

The spheres are neat -- and again, simple to do.  In fact, the spheres are
cheaper in terms of processing time than the polygons (which is why their demo
uses so many of them!).  Spheres never change shape; no matter what angle you
view a sphere from (within reason) it has a circular cross-section.  To move
them, you transform a single point -- the sphere's center; for a polygon, you
must transform every point (250 in the bishop, for example).

The spheres (as far as we can tell) are stored as bitmaps in VGA card memory;
these are just copied in, depth-sorted along with the polys.  Memory-to-memory
copies within the VGA card are very fast.  There are basically several copies
of the sphere at different sizes and colors.

Of course, the spheres don't change size smoothly with distance, but increasing
the spacing between them gives the illusion that they are.  Also, the
highlights never change (the brightest point is always at the top right of the
sphere); this serves to confirm the bitmap theory.

Still, fun to look at and well worth the download (if you have a VGA and
a 286 or better).  Whoever put it together did a *lot* of work.

As to whether REND386 will be faster... in a way, it already is.  The
bishban.plg file we use as our test case has 512 polygons in it; how many
polys did you see in even the most complex scene in vertdemo?  The thing that
makes theirs look so good is the metallic shading, which is relatively easy
to do, and the movement (which is also not hard).

---

From: Dave Stampe-Psy+Eng <dstamp@watserv1>
Date: Tue, 25 Feb 92 18:29:42 -0500

> From [email-masked] Mon Feb 24 22:36:51 1992
> To: rend386@sunee
> Subject: graphics demo
> It's called vectdemo.zip and it features probably
> the fastest 3d graphics I've seen on a PC
> (but that's not necessarily saying anything... :-)
> 
> It also features an audio track, but I don't have 
> a soundblaster so I can't comment on that.
> 
> Chris

Bernie managed to download it yesterday.  We spent an hour or so with a stopwatch and calculator and figured out what it does and how fast it really is.

Basically, it's not faster than REND386 for what it does (In fact, it's 
possibly slower).  It uses simple "flashy" effects and spheres (mode Y
sprites) to do its stuff.

If anyone has created graphics with REND386, you'll see its faster with
the 30-40 poly figures used.  Sphere's don't really count, as they are
easier to process than polys, and faster to draw.  But they'd be a 
problem in wide-angle VR displays (>80 degrees FOV) as they'd be distorted.

BTW has anyone actually bothered to create new objects for REND386 yet?

- Dave Stampe

---

From: [email-masked] (Marc A. Lefebvre)
Date: Wed, 26 Feb 92 11:59:23 EST

> BTW has anyone actually bothered to create new objects for REND386 yet?

	Well, I actually I have...  nothing to exciting because I was trying
to get used to the format of it.  First I created a house,  then a four and
five sided pyramid.  Right now I am attempting to create a octogonal (like a
really rough soccer ball) shape.  Is there an easier way than just plotting
on 3D graph paper; maybe a program that creates PLG files from some graphics
drawing program that converts to that format?

> - Dave Stampe

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---

From: Chris Hand <[email-masked]>
Date: 26 Feb 92 23:12

RFC-822-HEADERS:
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==================
> BTW has anyone actually bothered to create new objects for REND386 yet?

Creating .PLG files manually seems less than attractive
at the moment... has the OFF->PLG converter seen the light
of day yet?

On a related note, anyone know of any *free* programs to
manipulate/create 3D models?  .DXF support? ah well...

Oh yes, and what's "ThingWorld"?

Chris

"end of term soon... then I can get some *interesting work done!" 
:-)

---

From: Dave Stampe-Psy+Eng <dstamp@watserv1>
Date: Wed, 26 Feb 92 19:06:45 -0500

Thingworld is a X-based system developed over the last 10 years at MIT.
It defines objects as geometrical, distortable shapes, then polygonizes
these for each frame.  Advantages: easier collison detection (so they
claim!) and realiztic modelling (clay) and dymanic distortions.
Disadvantages: too slow for complex real-time worlds (A few figures
can be done at a half-decent rate).  This came up during discussions
on collision detection on sci-vw, so I dug up the papers.

- Dave Stampe