From: georgef@endeavor18.wv.tek.com (George Forman = GHF)
Subject: TECH: OIFF an object interchange file format
Date: Fri, 21 Aug 92 15:18:02 PDT



I have a few suggestions for OIFF:

1. You might include a version # in the header.  This will probably
save grief later.

2. In the 2-D world, people have found it very useful to include a
bounding box in the Postscript files.  This saves scanning the whole
thing to find out if it's in the field of vision or whatever.  Also
aids scaling-- suppose I want to put Jim's world in a shoebox on my
shelf.

3. Perhaps some notion of subroutines could be incorporated to reduce
data size.  A 1 page description in a slightly higher level graphics
language can produce a scene filled with 1000s of polygons.  The OIFF
files will blow up geometrically-- each of the 40 houses each have 15
boxes which each have 6 sides.  A very low-level OIFF will have to
represent an awful lot of data, but a slightly higher-level OIFF can
be much smaller.  I suggest such simple languages as found in computer
graphics course textbooks.

4. The file could specify the 6 light reflecting characteristics of a
flat surface (RGB reflected & RGB diffuse) & let the *user's* display
program decide whether to just quickly use a flat color model (just
using the first 3 numbers), or to produce a beautifully lighted model
using all 6.  To save space, suggest that the OIFF define a color map
which the polygons then use by reference.  In the future, this color
map could become sophisticated w/ texture & tiling information.  You
certainly wouldn't want each polygon to have to specify all this
information explicitly each time-- takes a lot of polygons of the same
color to make a blue tree.  These are probably frills for the second
version.

5. Suggest making the file more readable & printable.  Right now it
seems extremely vertical-- could waste a lot of printer paper.
Wouldn't hurt to use a tab character between components of a vertex &
newline after each vertex, or commas and tabs.

6. I'm not so certain that things should be broken up according to the
5 senses: SOUN,VISI,HAPT,OLFA,TAST.  Yes, it's stable over centuries,
but I'd think it'd be better to break things up according to the
virtual devices on which they are to be displayed.  The 3-D world
device (probably HUD, but perhaps not.), a much higher quality 2-D
device (for text, explanations, detailed menus, high-resolution
pictures etc. which won't work well on HUD), general room lighting
device (RGB diffuse light? Strobe?), pack vibrator, floor vibrator,
room heater...?

Good luck,

  GHF