[GEM-dev] How to change perspective Angle in Gem : WAS gemwin "view" message

[B. Bogart]

Thanks Cyrille,

I (think) I figured it out through visual experimentation, that is
changing the perspec and swapping views until all three squares are
visually the same size.

I did not get a chance to test it yesterday, but I'll be in the lab
tomorrow to give it a wirl...

Thanks again all,

.b.

cyrille henry wrote:
> hello,
>
> i don't understand the question, but :
> tan (angle) = size of the window / distance of the camera.
> (so, you don't nead unit).
>
> otherwise, a good openGL book with a clear graphic of what exactely
> perspec and view message are is the only thing you nead...
>
> cyrille
>
>
> B. Bogart a écrit :
>
>> hi Cyrille,
>>
>> Thanks!
>>
>> seems a little obvious now, I think I was trying to change the
>> perspective
>> angle by trying to move the Z planes, not the XY planes!
>>
>> So the question is:
>>
>> I know what angle I need, or what size and position I want the gemwin to
>> be, but I don't know how to map this to the units of perspec.
>>
>> What do the perspec units mean?
>>
>> I'll keep messing around...
>>
>> Thanks for the tip!
>>
>> .b.
>>
>> On Mon, April 3, 2006 3:06 pm, cyrille henry said:
>>
>>> hello,
>>>
>>> i think you should use more the perspect message than the view message.
>>>
>>> try by example :
>>> perspect 0 2 -1 1 1 20
>>> and
>>> perspect -2 0 -1 1 1 20
>>> to create 2 screens that perfectilly connected.
>>>
>>> you can also try :
>>> perspect  0 $1 -1 1 1 20
>>> to adjust the lens...
>>>
>>> Cyrille
>>>
>>>
>>>
>>> B. Bogart a écrit :
>>>
>>>> Hey all,
>>>>
>>>> Anyhow I tried another approach to my setup so that all the three
>>>> virtual
>>>> cameras require the same lens, but alas it still does not work since
>>>> the
>>>> default lens of the camera does not match what I would like.
>>>>
>>>> A quick run down of what I'm doing:
>>>>
>>>> I have a (physical) space with three rear-projection screens. I want to
>>>> have three gemwins (on different machines) that each sees the gemworld
>>>> from the view of each of these physical screens. They are fixed in
>>>> space,
>>>> surrounding a room at angles (see attached filen which shows the
>>>> view of
>>>> the room from the top). Basically the virtual gem-space is then mapped
>>>> into the physical space on multiple screens. (cave-like, but of course
>>>> not
>>>> a cube of screens)
>>>>
>>>> So its easy enough to get the camera to point at the center of each
>>>> virtual screen, but the edges of the screen don't match the edges of
>>>> the
>>>> gemwin. (in the attached OOo diagram we should see only the red square
>>>> in
>>>> screen 2, and the green square in screen 3, but both the red and green
>>>> squares are visible in both screen 2 and screen 3.
>>>>
>>>> Method-A and Method-B slides show the two options for the camera views,
>>>> in
>>>> option A the camera plane is parallel to the screen plane, but the
>>>> distances  from camera to screen are different. In method-B the camera
>>>> is
>>>> the same distance from all the screens, but for screen 2 and 3 the
>>>> camera
>>>> plane is not parallel to the screen plane.
>>>>
>>>> Also I included a few attached patches:
>>>>
>>>> virtual-camera-test2 is method-A
>>>> virtual-camera-test3 is method-B.
>>>>
>>>> I'd really like to get this resolved, since we're hoping to do many
>>>> gem-projects in this space with these three screens...
>>>>
>>>> Thanks all,
>>>> .b.
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> ------------------------------------------------------------------------
>>>>
>>>>
>>>> _______________________________________________
>>>> GEM-dev mailing list
>>>> GEM-dev at iem.at
>>>> http://lists.puredata.info/listinfo/gem-dev
>>>
>>>
>>> _______________________________________________
>>> GEM-dev mailing list
>>> GEM-dev at iem.at
>>> http://lists.puredata.info/listinfo/gem-dev
>>>
>>
>>
>>
>>
>> _______________________________________________
>> GEM-dev mailing list
>> GEM-dev at iem.at
>> http://lists.puredata.info/listinfo/gem-dev
>>
>>
>
> _______________________________________________
> GEM-dev mailing list
> GEM-dev at iem.at
> http://lists.puredata.info/listinfo/gem-dev
>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 256 bytes
Desc: OpenPGP digital signature
URL: <http://lists.puredata.info/pipermail/gem-dev/attachments/20060404/b67a22b0/attachment.pgp>