Re: [HACKERS] One more globe

From: jwieck(at)debis(dot)com (Jan Wieck)
To: maillist(at)candle(dot)pha(dot)pa(dot)us (Bruce Momjian)
Cc: jwieck(at)debis(dot)com, clark(dot)evans(at)manhattanproject(dot)com, pgsql-hackers(at)postgreSQL(dot)org
Subject: Re: [HACKERS] One more globe
Date: 1999-03-18 12:07:14
Message-ID: m10NbZy-000EBdC@orion.SAPserv.Hamburg.dsh.de
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Bruce Momjian wrote:

> > Well - you wanted mountains - there they are (Example 2).
> > But please don't tell me next you want planes in the air,
> > smog over NY and dolphins in the sea :-)
>
> Jan, is there no limit to what you can do?

Rayshade has no wireframe objects like POVray. A wireframe is
an elegant way to describe complex things like e.g. screws.
In rayshade you have only some primitves like sphere, box,
cone, cylinder and some flat things like triangle, disc and
polygon. The problem with missing wireframes is that things
like characters are really hard to define.

Anything to build must be described as combinations of such
primitive objects. This process is called Constructive Solid
Geometry (CSG). For example to make a hole in a wall you take
a box and scale it to 5.0, 0.2, 3.0 (x,y,z). Now you take
another box, scale it to 1.0, 0.21, 0.5 move it into the
center and subtract it from the wall. There is now the hole
where you can put in the window. If you build four walls
don't forget the hole for the door :-)

Another powerful primitive is the heightfield (what I've used
to build the mountains on the map). It uses a special file of
raw floating point values that describe the altitude of a
point on a square plane. I've used the etopo5 topography data
(altitudes in meters for every 5 minutes of the earth,
4320x2160 points though) and converted that into such a
heightfield plus a color image ranging from deep blue at
ocean bottom to white on the altitude of the himalaya.

Look here for some other examples what's possible with these
few features:

http://www-graphics.stanford.edu/~cek/rayshade/gallery/gallery.html

My favorites are Chem, Trees, Magic Chain and of course the
scenes from Nathan Obrien! The final PostgreSQL developers
globe might be another candidate for the gallery :-)

Jan

--

#======================================================================#
# It's easier to get forgiveness for being wrong than for being right. #
# Let's break this rule - forgive me. #
#======================================== jwieck(at)debis(dot)com (Jan Wieck) #

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