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In the working docs ( section 6.4) I read:
"Depending on the projection type some of the parameters are required,
some are optional and some aren't used."
But: which parameters are required ex. for the orthographic projection
(the one I use for my mathematically oriented images ex.
http://cage.rug.ac.be/~hs/ )?
As to the orthographic projection the working docs aren't much clearer:
"6.4.2.2 Orthographic projection
This projection uses parallel camera rays to create an image of the
scene.
If you replace the perspective keyword by orthographic and leave all
other parameters the same, you'll get an orthographic view with the same
image area, i.e. the
size of the image is the same. You should be aware though that the
visible parts of the scene change when switching from perspective to
orthographic view. As long as all
objects of interest are near the look_at point they'll be still visible
if the orthographic camera is used. Objects farther away may get out of
view while nearer objects will
stay in view."
Is there somebody who can give a short and clear explanation?
Friendly greetings,
--
Herman Serras
Gent (Belgium)
http://cage.rug.ac.be/~hs/
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I **finally** stumbled onto the correct syntax after getting no help from
the docs.
camera {
orthographic
location <1000,0,0>
up y
right 4/3*x
look_at <900,0,0>
angle 90
}
The important parts here:
(a) Your "location" needs to be greater than your "look_at" (an obvious
requirement, but bears repeating), and probably should be on a parallel
axis. For example, in the camera definition above I am 1000 units out on the
x axis, looking at a "viewing plane" that is exactly 100 units away (at 900
x units), but with the same y and z offsets.
(b) Your aspect ratio for your rendering needs to match what you put in your
"up" and "right" statements. For example, if you are doing a 640x480
rendering (4:3 aspect ratio), your "right" statement should be "right
4/3*x". If you are doing a perfectly square (1:1 aspect ratio) rendering,
you would have "right x". If you're doing an image that is taller than it is
wider (e.g., 400x300), you would change the "up" statement instead of the
"right" statement (e.g., "up 4/3*y right x").
(c) You have to have an "angle" statement at the end. The smaller the
number, the closer you zoom in to the viewing plane specified in "look_at".
Once you do all that, it should work. (Of course, toruses still look like
crap in orthographic... *sigh*).
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