Dennis Pierce (dpierce++at++sgimco.orlando.sgi.com)
Fri, 4 Feb 1994 17:39:02 -0500
an occulting object is just a blob - in its most simple form, the
object is just a screen dot (pixel) - a more advanced form would
be an alpha blended gaussian distributed circle where the outer
edges are nearly transparent and the center is opaque - I didn't
want to sound so pedestrian by saying "pixel" because my old
system didn't have any transparency features and I think that it
would be quite beneficial to explore a more "correct" presentation
with this new fancy RE hardware
but...
please understand that ANY additional use of transformation and
fill hardware will be difficult to justify, so the simpler, the
better - and I think you'll find that a few streaks (for rain)
or a few floating pixel clusters (for snow) will be sufficient to
convey a reasonable presentation of precepitation - also, be
aware that the successful implementation of this will probably be
largely based on "fooling" the eye into thinking that more is being
shown than is actually being presented - I don't think there is
sufficient bandwidth in the RE to draw a physical model of rain
or snow PLUS do the real task of terrain, culture and models
the real novelty of the approach presented is that it solves the
problem of having dots fall in a controlled manner with two simple
linear arrays - contrast this with a full-up 1280x1024 array
this pseudo-random approach can also be used to generate random, but
repeatable ground features such as roads, tree patterns, bush clutter,
and the like - for some applications, the rapid generation of "good
enough" terrain and culture can be done procedurally instead of
actually modeling the features - this gives an "infinite" scape to
play on without having to actually build the model first - I'm sure
the approach has been implemented a couple of hundred times by the
real IG folks
hope this helps...
bye.
-- Dennis Pierce, SGI, 900 Winderley Place, Ste 130, Maitland, FL 32751 email: dpierce++at++sgi.com vmail: 8548 tel : 407.660.0073 late : 407.660.2789 fax : 407.660.8981 cell : 407.256.8447
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