Giga Games 1/Giga Games.iso/net/vir_real/faq/schools/nc.2

Text File | 1992-01-24 | 5.9 KB | 106 lines

91-07/3dm.info

> Also, is there a system yet that allows the user to build an environment
> from within it? I know most make you build it from outside using a mouse-
> driven CAD-type program and then you go into it.
>
> Rudy
> [e-mail]

I'm a grad student at the UNC-Chapel Hill Computer Science department, and I
can proudly attest to the fact that there is such a system.  It was written
in the Spring 1991 semester by Jeff Butterworth, Steve Hench, Marc Olano and
myself for a COMP 145 Software Engineering project.  The program, called 3dm
(for 3D Modeler) runs using VPL Eyephones and a 6D mouse that consists of
a Polhemus in a billiard ball with two buttons.  The program runs on Pixel
Planes 5, a custom graphics engine developed here at UNC.   Pixel Planes 5 can
display up to 1,000,000 (yes, 1 million) shaded (phong with specular
highlights) polygons (of any size) per second on the screen.  Pixel Planes 5
supports up to four viewpoints (i.e. two users with stereo vision).

3dm's virtual world includes a "toolbox" which is a rectangular palette like
those found in most Macintosh drawing applications.  The toolbox cells
contain 3D icons that represent tools (extended modes of operation) and
commands (which execute immediately).  The toolbox can be grabbed and
repositioned, and "locked" so that it follows the user at a fixed distance
and is (almost) always within reach.

3dm models consist entirely of triangles.  Pixel Planes 5 supports n-gons,
and support in 3dm will probably be added soon.  The main tool in 3dm is the
Mark tool, which can "mark" triangle vertices and groups of vertices in a
model.  A triangle counts as marked when all of its vertices are marked.
Vertices near the cursor (a 3D arrow) are tracked -- each vertex hilites when
the cursor is near it and the cursor snaps to its position.  Marked vertices
and triagles can then be moved with this tool.  Vertices can also be moved
individually to deform objects (like sculpting).  Many vertices can be
marked at once by dragging out a wire frame box to mark all vertices within
it.

Objects can be created with the Extrusion tool.  The user can define edges
(or mark existing edges) by clicking at the vertices, and dragging then
creates a surface between them.  A Triangle tool allows the creation of
individual triangles and rapid creation of triangle strips.  Because of vertex
tracking, triangles (and pretty much any other object that is created) can be
easily connected to existing vertices.  Marked triangles can be scaled up or
down with the Resize tool (which may be incorporated into the Mark tool by
giving selected objects "resize handles" like on the Macintosh).

There is also a Box tool for dragging out 6-sided boxes.  A Sphere tool
allows the user to create polygonal spheres.  Pixel Planes 5 supports
spheres as a primitive, but they cannot be sculpted and deformed. (3dm uses
small sphere primitives to indicate a vertex is marked, BTW).  Other tools
may be added that allow other high-level objects to be created easily.

Flying around the virutal world is accomplished with the Fly tool -- you
fly in the direction you point and click.  The virtual world may be grabbed
as a whole and rotated with the Rotate World tool.  The world scaling can
be controlled with the Scale World tool, so you can see your virtual objects
from the point of view of an ant or Godzilla.

Clipboard commands (Cut, Copy, Paste, Erase) are supported, as are infinite
levels of Undo and Redo.  There is a Color Selector menu for changing
triangles' color.  Pixel Planes 5 also supports textures (though this slows
down the frame rate somewhat), although they has not yet been incorporated
into 3dm.

Triangles can be grouped with the Group command, and group hierarchies can be
created with the Parent command.  By copying and pasting a selected group,
another instance of the group is created.  All instances are automatically
updated when one is modified.

Precision ("I want to click right...there...dang!") has been a big problem,
considering the jitteryness of the Polhemus.  It's really easy to make
"natural-looking" (read: asymetrical :-) things (like a tree), but pretty hard
to make symetrical things (like cars or planes).  Vertex tracking helps a
*LOT*.  The box and other high-level-object creation tools are also useful.
Sometimes it helps to scale the world up and work with the model at a larger
scale.  But with the help of snap-to-gridding, a floor plan of a building can
be drawn on a plane and extruded up at right angles -- instant walls.  We have
several ideas for other constraints (like virutal mirrors for creating
symmetrical objects) in the works.

The toolbox icons are not very intuitive to first-time users, so we have
thought about putting many of the commands into pull-down text menus.  The
extremely low resolution of the Eyephones makes it difficult to display text
unless it is quite large in the virual world.  Text will definitely be used to
some extent, however.  Also on the wish list is a virtual keyboard, for
entering file and group names, and a virtual "standard file" interface like
on the Mac.  This summer I wrote high-level routines for easily creating and
manipulating virtual "windows"/palettes (like the toolbox), controls (like
each icon cell in the toolbox), and pull-down menus, so I suspect these
wish-list features are not very far off at all.

3dm, and many other absolutely staggeringly amazing applications will be
on display at the Virtual Reality Applications Gallery at SIGGRAPH '91.
I hope to see everyone there.  A spendid time is guaranteed for all.  ;-)

Later,
Drew

--
Drew Davidson        \\     HELP FULLY INFORM JURORS!  TELL YOUR FRIENDS:
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