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From: carlos@io.UUCP (Carlos Smith)
Newsgroups: comp.sys.amiga
Subject: Re: Sculpt 3D, ray tracing. (Bugs with morerows and screenblanker)
Message-ID: <365@io.UUCP>
Date: Tue, 25-Aug-87 12:10:38 EDT
Article-I.D.: io.365
Posted: Tue Aug 25 12:10:38 1987
Date-Received: Wed, 26-Aug-87 07:12:28 EDT
References: <362@io.UUCP> <606@phoenix.PRINCETON.EDU>
Reply-To: carlos@zapp.UUCP (Carlos Smith)
Organization: Interleaf, Cambridge, MA
Lines: 54

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
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