home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
ARM Club 3
/
TheARMClub_PDCD3.iso
/
hensa
/
graphics
/
b133_1
/
!Readme
Wrap
Text File
|
1993-12-09
|
7KB
|
149 lines
Readme file for the Earth demo package
© 1993 Florent de Dinechin
These files are public domain. You may freely copy and distribute them,
as long as you distribute this cultural file along,
but you are not allowed to charge for them. None of these files may be
included or partially included in any commercial product or magazine disk
without my prior agreement and the huge money order needed to get it.
****************************************************************************
Florent de Dinechin
fdupont@irisa.fr
Real world: 9, rue la Fontaine F-35700 Rennes (France)
****************************************************************************
This package contains the following demos:
!Earth25 Simple earth globe rotating in mode 25 (for A4)
!Earth13 The same in color and mode 13 (any monitor)
Just launch them and look. You should see an earth globe (is that zum Teufel
the correct word... I don't have a dictionnary here).
The earth rotates by itself. You can shift to mouse-controlled rotation
by pressing any mouse button. And back.
The color version is much nicer.
And now, the real thing:
!EarthRB The same, but in real 3D, using red-blue glasses.
(or red-green)
!Earth3D25 Real 3D without glasses, but with a piece of cardboard...
!Earth3D13 idem
Each of these progs works better in the dark (as I do).
Each of these programs computes 2 views of the earth, one for the left eye
and one for the right eye. You need then to get each picture to the proper
eye:
With !EarthRB you just need to place a red filter on your left eye
and a blue one on your right eye. You should then see the globe
in real 3D. Shift from red/blue to red/green with the mouse buttons.
It's damn slow because I use the system's drawing routine,
ORed in this case. It should get better later.
The program is tuned for my Acorn TV monitor. For example, on this monitor,
full red seems much brighter than full blue, but about as bright as full
green. You can edit the first three lines of the BASIC !Runimage to adjust
the constants BLUELEFT% and GREENLEFT% if you find that the picture on
one eye is brighter than on the other eye. It depends on the glasses, too...
With !Earth3D25 and !Earth3D13, both pictures are displayed side by side.
To see the picture with these two programs:
1. Push the mouse on the top left corner, and move it then slightly to the
right, until you see a small stripe of stars, and two distinct small
earthbowls.
2. Use a piece of cardboard (A4 size or bigger) to separate both pictures:
there are two small white lines to materialize the vertical separation
line; place one edge of the cardboard on this line, and your nose on the
opposite edge, so that each eye can only look at one half of the screen.
It is better to work in the dark so that the eyes concentrate on the screen.
3. You should now see the stars, and a small earth slightly in front of them.
4. Moving the mouse up-down makes the earth come nearer.
5. Moving the mouse left-right increases the width of the picture. You need
a wider picture when the earth comes closer, as it gets bigger. But you
can't see anymore if you separate too much the pictures(your eyes can't
see further than infinite, see below). In this respect, the smaller the
screen, the better... Sorry for the rich owners of huge multisyncs, but
you had better use a very small TV set to test this.
6. Real Men can see it without the cardboard.
***************************************************************************
To understand why you get an headache, I need to give a basic lesson in
depth perception, but I lack the technical words, so if you don't
understand, just learn french and I'll explain to you.
Or ask an optician.
The basic idea is that my progs create a conflict between the focus
position of each eye, and the convergence (?) position: the eyes focus at
a picture which is 50cm away, but need to aim at this picture as if it were
much further: the maximum value you can move the mouse to the right makes
your eyes aim parallel, as if they were looking at the stars, at infinite
distance. Meanwhile, they focus at a small distance... It works well anyway,
but it is confusing for the brain.
You can reduce this effect by using magnifier lenses, one for each eye.
It will project your screen to the infinite, thus relaxing the focus
muscles. Besides it will lower another confusing effect, which is that the
focus value for the stars and the earth is the same, though one is closer
than the others. As the infinite is about five meters away in terms of eye
focus, this will disappear if (in the virtual world) the stars at at the
infinite and the earth is 5 meters away...
***************************************************************************
Autocritics and future improvements:
------------------------------------
1. I know, everything should come in only one application,
with menus to chose the monitor and everything...
2. Anybody knows where to find a file with coordinates of the earth? I got
mine by computing the inverse-Mercator projection of a map I designed with
the mouse on my screen. It is, well, approximate. Look at the North Pole...
3. For the colour version, I rewrote a fast draw routine. It would't be much
to have this one run in higher resolution, but I donot have a multisync
to test it. It's a pity because my technique uses only a small stripe
in centre of the screen, and I want to allow as much pixels in this
stripe as possible. Therefore, send money or multisyncs to the address above.
(No, no, it's a joke, don't send multisyncs, I don't have the room. First,
send money so that I can bye a victorian house, and then I will be able
to fill it with multisyncs. No, it's another joke. Go and buy doze with
the money and drink it à ma santé in front of the multisync displaying
beautiful naked women in high-res. Or send it to the unemployed battered
baby whales victims of acid rains and AIDS (the money, not the doze
neither the multisyncs). It's Christmas.)
4. I think the thing with the depth perception is great, and I will
probably write a small PD Blastallgame using it. Or maybe the kind of
filer you can see in Jurassic Park (which I confess having seen, but
with a purely professional point of view, of course). Any suggestion
by e-mail welcome.
5. I am also thinking of a SIRD approach: you could then see the thing
without any cardboard or glasses, but with a much improved headache.
5. Don't tell me about a hidden surface version.
(Actually I'm working on it, it should be ready in a couple of decades now:
I'm fighting with my clipping routine in polygon-filling, and I am not quite
sure, who the winner will be.)