[comp.sys.amiga] Sculpt 3D, ray tracing.

carlos@io.UUCP (Carlos Smith) (08/21/87)

I have been happily playing with Sculpt 3D for the last two weeks. It is a 
wonderful program (already one of my favorites on the Amiga) and Eric Graham
has done a wonderful job of taking something inherently difficult (3D design
on a 2D display) and made it easy to use, but powerful.

I recommend this program to anyone interested in 3D design and ray-tracing. It
is NOT an animation program, but is meant as a modeling and rendering package.
A companion animation package may be done "in a few months" (Byte-by-Byte rep
at Siggraph). One of the nice things about Sculpt 3D is that it is easy to
learn, and well-documented. The user interface is very well thought out: it
seems to have a minimal number of tools (some important ones seem to be
missing at first), but with use one finds that almost anything can be 
accomplished fairly easily. Colors and surface properties of faces are
selectable. Color is set with sliders (no fixed palette), among the surface
properties are dull, shiny, mirror, transparent. Light sources can be colored.
Viewing is easily set up with a target and observer. "Lenses" are selected 
to alter viewing of the scene (normal, wide angle, telephoto and selectable).
Smoothing of planar facets is selectable on a face by face basis. The imaging
modes include wireframe (no hidden line removal, good for fast scene setting),
paint (flat shaded faces, much faster than ray-tracing), snapshot (ray-tracing
without shadowing, HAM output) and photo (shadowing, HAM output).
Anti-aliasing is also selectable, as well as interlace and high-res (for 
non-HAM modes - HAM is 320 only, right?). There are also several image sizes
for very fast ray-tracing just to get a feel for whether lighting and camera
postion are correct. One nice thing is that rendering is a background process,
you can continue to work on a model while it or another is being rendered.

A couple of warnings though. I have found destructive interference between
Sculpt 3D and Morerows, as well as with Screenblanker (from Charlie Heaths
FastFonts package). Morerows seems to confuse it as to the image size of the
rendered image, to the point where if the image is saved and immediately
reloaded, it is shifted to the right and wraps around to the left, and a
requester tells you "Error loading image". It also does not load correctly 
into DigiPaint (a great companion, since it allows you to touch up and/or
work with the results of the ray-tracing, since they are in HAM mode). This is
solved by eliminating morerows. Oh well.  The interference caused by 
screenblanker is very bizarre. In HAM mode large images take a LONG time (I
have had them go overnight easily, especially with mirrors). At some point
screenblanker kicks in, dimming the colors in the screen used for the 
ray-traced image. Apparently the HAM algorithm looks at the brightness of the
preceding "real" pixel, decides how bright it wants this one and sets the 
color accordingly. The result is that the HAM colors are fine with the screen
dimmed, but when you move the mouse and the colors go back to full brightness,
there are garish bright streaks across the image emanating from the leftmost
"real" pixels. Its kind of neat to see the HAM interaction, if it didn't take
ten hours to do it! So no more screenblanker either... Thanks to Jim Shook 
for warning me about morerows...

It is not copy protected. I hope this doesn't mean it will be heavily pirated,
the guy did a hell of a job. One Meg or more is recommended for complex
scenes.

Speaking of copyrights, I got a real shock today at the NCGA CAD expo in
Boston. While passing the Intergraph booth, a friend said "Hey, that looks
familiar!" There was the Juggler, running in a window on an Intergraph 
workstation! Is the workstation really an Amiga?! Is it the first Amiga 
clone?! No, actually it seems to be another case of a stunning Amiga demo
finding its way onto other machines, this time a very high end workstation.
Is the juggler copyrighted by Eric Graham? It is certainly as readily
identifiable as Red the unicycle. I get the feeling that Mr. Graham is more
likely to be flattered than to break out the lawyers. I could be wrong...

By the way, many Amigans are taking the wrong tack in the "Mac multitasking"
war. Everyone is pointing out that they can do ray-traces in the background
while accomplishing real work (certainly true). But Mac people will not 
comprehend this. Ray traced images are just not very impressive on a tiny
black-and-white display. Tell them they can have multiple copies of the
talking moose arguing with each other. This they will appreciate. 
-- 
			Carlos Smith
			uucp:...!harvard!umb!ileaf!carlos
			Bix:	carlosmith

kpmancus@phoenix.PRINCETON.EDU (Keith P. Mancus) (08/21/87)

Subject:  3D design programs

  Hello again.  I bought my Amiga primarily because I thought it would
be an excellent system to do design (blueprint) work on.  I am
a student majoring in aerospace engineering, just about to enter junior
year.  Since my courses in aeronautical design are about to start,
I figured I'd buy it now and get used to it on the school projects.
  Now, to the question:  are there any engineers out there who have
been using Amigas as design (CAD) tools?  I've used AutoCAD on the
PC, and I thought it was useful but was disappointed that it didn't
support "true" 3D (i.e., it only handles linear extensions of 2D
objects).  I'd like an easy-to-use program that lets me do true 3D
design, then rotate the image to see it from all angles.  It has
to support a complex shape, like a tapered wing or a fuselage with
compound curves.  Any program names (Sculpt 3D, perhaps?) with short
reviews, plus comments on how much memory I should get, would
be appreciated.
  Thanks!

  -Keith Mancus <kpmancus@phoenix.princeton.edu>

jdow@gryphon.CTS.COM (Joanne Dow) (08/25/87)

In article <362@io.UUCP> carlos (Carlos Smith) writes:
>
>I have been happily playing with Sculpt 3D for the last two weeks. It is a 
>wonderful program (already one of my favorites on the Amiga) and Eric Graham
>has done a wonderful job of taking something inherently difficult (3D design
>on a 2D display) and made it easy to use, but powerful.
>
>A couple of warnings though. I have found destructive interference between
>Sculpt 3D and Morerows, as well as with Screenblanker (from Charlie Heaths
>FastFonts package). Morerows seems to confuse it as to the image size of the
>rendered image, to the point where if the image is saved and immediately
>reloaded, it is shifted to the right and wraps around to the left, and a
>requester tells you "Error loading image". It also does not load correctly 
>into DigiPaint (a great companion, since it allows you to touch up and/or
>work with the results of the ray-tracing, since they are in HAM mode). This is
>solved by eliminating morerows. Oh well.  The interference caused by 
>
>-- 
>			Carlos Smith
>			uucp:...!harvard!umb!ileaf!carlos
>			Bix:	carlosmith

As you may have read already, Carlos, the problem resides in the Digi-whatever
products. Alas, Tim has not set them up to handle overscan. So overscan images
in ham mode produced by ANY program won't load into them correctly. It appears
Sculpt-3D is clean on this issue. (It may be slowish; but, Hoo Boy are the
images it produces NICE!)
(Check out the Byte by Byte vendor support conference on Bix. Scott and Eric
are checking in there these days, bless them!)

-- 
<@_@>
	BIX:jdow
	INTERNET:jdow@gryphon.CTS.COM
	UUCP:{akgua, hplabs!hp-sdd, sdcsvax, ihnp4, nosc}!crash!gryphon!jdow

Remember - A bird in the hand often leaves a sticky deposit. Perhaps it was
better you left it in the bush with the other one.

carlos@io.UUCP (Carlos Smith) (08/25/87)

in article <606@phoenix.PRINCETON.EDU>kmancus@phoenix.PRINCETON.EDU 
(Keith P. Mancus)

asked:

>I'd like an easy-to-use program that lets me do true 3D
>design, then rotate the image to see it from all angles.  It has
>to support a complex shape, like a tapered wing or a fuselage with
>compound curves.  Any program names (Sculpt 3D, perhaps?) with short
>reviews, plus comments on how much memory I should get, would
>be appreciated.

Sculpt 3D is more of an artists tool than an engineering tool. This is its
weakness and its strength. It is very easy to learn, and to use. But
everything is done by eyeball. A coordinate read out window is available,
but it cannot be used to enter coordinates. I sometimes find it very
frustrating lining things up by eye, trying to move the mouse
oh-so-carefully up one pixel without moving it over... Two things this program
could really use are constraints (horizontal, vertical and diagonal) and a
grid. Also, only three orthogonal views are available. It is not possible to
define an arbitrary working plane, other than (by eye) selecting an object and
rotating it until a face is paralell to a view. Rotation effects OBJECTS not
VIEWS, so if you just want a better angle to work on something you have to 
move it and then move it back. For VIEWING ONLY you can view the object 
flexibly by changing the target point, observer point and lens. But the
object cannot be edited in this mode.

Smooth curves and surfaces exist only to the extent that they can be 
approximated by triangular faces. Cylinders, spheres, hemispheres, cones
and tubes exist as primitives, they are all approximated by triangular facets.
The number of subdivisions is selectable by the user at the time of creation.
There is also the provision for subdividing existing faces, manually
recursively subdividing and adjusting vertices is the only way to approximate
an arbitrary curved surface. At rendering time (ray-tracing modes only) a
surface smoothing attribute applies what seems to be either Phong or Giroud
shading to the faces, making them appear much smoother than they are.

Forms-in-Flight takes a different approach. I have not yet worked with it
as much, but I can say it also is not an engineering tool. Both of these
programs lack critical features required to make them engineering tools 
(layers, flexible referencing of existing geometry, arbitrary view definition,
constraints). But Sculpt 3D is still one of my favorite Amiga programs. 
Hopefully one or both of these will grow into an engineering tool without
losing their ease of use and flexibility.

I hope this has helped give you an idea of the capabilities of Sculpt 3D at
least. I will say more about Forms-in-Flight when I have worked with it
more.


-- 
			Carlos Smith
			uucp:...!harvard!umb!ileaf!carlos
			Bix:	carlosmith

carlos@io.UUCP (Carlos Smith) (08/26/87)

In article <1320@gryphon.CTS.COM. jdow@gryphon.CTS.COM (Joanne Dow) writes:
.In article <362@io.UUCP. carlos (Carlos Smith) writes:
.
..A couple of warnings though. I have found destructive interference between
..Sculpt 3D and Morerows, as well as with Screenblanker (from Charlie Heaths
..FastFonts package). Morerows seems to confuse it as to the image size of the
..rendered image, to the point where if the image is saved and immediately
..reloaded, it is shifted to the right and wraps around to the left, and a
..requester tells you "Error loading image". It also does not load correctly 
..into DigiPaint (a great companion, since it allows you to touch up and/or
..work with the results of the ray-tracing, since they are in HAM mode).
.. This is
..solved by eliminating morerows. Oh well.  The interference caused by 

.As you may have read already, Carlos, the problem resides in the 
.Digi-whatever products. Alas, Tim has not set them up to handle overscan.
. So overscan images in ham mode produced by ANY program won't load into them
. correctly. It appears Sculpt-3D is clean on this issue. (It may be slowish;
. but, Hoo Boy are the images it produces NICE!)

Uh, I appreciate your response, but the problem also occurs without any use
of Digi-anything products. If I am using morerows, I can create a full (not
jumbo) sized HAM image in Sculpt 3D, save it and then load it, all in one
session. The screw up happens entirely in Sculpt 3D. If it also happens in
DigiPaint, well then DigiPaint has a problem too. I can't really blame Sculpt
3D for either problem, it seems to me that overscan support is a grey area.
But then, if the Amiga 3000 comes out with 1kx1k graphics, I suppose it won't
work then either. So it ought to be supported now, 'cause its going to have to
be supported later.

-- 
			Carlos Smith
			uucp:...!harvard!umb!ileaf!carlos
			Bix:	carlosmith

peter@sugar.UUCP (Peter da Silva) (08/28/87)

In article <365@io.UUCP>, carlos@io.UUCP (Carlos Smith) writes:
> an arbitrary curved surface. At rendering time (ray-tracing modes only) a
> surface smoothing attribute applies what seems to be either Phong or Giroud
> shading to the faces, making them appear much smoother than they are.

If the faces are shaded (either flat or via Phong or Giroud shading) then it's
not doing ray tracing. Phong shading, where you average the normals to the
surface across the face, is similar to what you do to smooth ray traced
objects. Unless I'm completely wet, though, Giroud shading is done by averaging
the colors of the corners across the face... which is completely alien to
what you do with ray tracing.

That's not to say I'm not completely wet... but I don't think so.

Also, is "Giroud" the correct spelling?

Have you seen the recent issue of Science News with the incredible ray-traced
image in it?
-- 
-- Peter da Silva `-_-' ...!seismo!soma!uhnix1!sugar!peter
--                  U   <--- not a copyrighted cartoon :->