[PD] GEM mapping units to pixels
altern2 at gmail.com
Sat May 12 12:38:59 CEST 2007
do you mean something like the example attached?
This doesnt work ok for me, the shape should be 10x10 px and is not,
also x and y pos are dont match with window size. Translating to 400,
300 should place the rect in top right corner but I get that with only
320, 190, so the units are not mapped to pixels
but maybe i am missing something from what you describe?
In opengl to achieve this 2D like-pixels to units effect i would
set the perspective to be orthographical with glOrtho command, is
something like this possible in Gem?
cyrille henry(e)k dio:
> i tried with :
> dimen 400 300
> view 0 0 1000 // 1000 is in order to put the camera far from the view
> point, to reduce space distortion
> perspec 0 400 0 300 999 1001 // 999 and 1001 limit the render to
> primitive position is between -1 and 1 (because camera is at 1000)
> and everything is working as expected.
> i just have 1 strange thing : i need to set the [dimen<, [create< ,
> then [reset< and last [view< and [perspec< if i did not do a reset, a
> square is not rendered as a square but a rectangle.
> anyway, it's working.
> altern a écrit :
>> i tried to pass different view values to gemwin. I can see that in
>> order to be able to specify location or with with pixels i should set
>> view to
>> view 0 0 2
>> but as soon as i set that the shape is not there any more. This is an
>> example i am using to test. If i ser view to
>> view 0 0 2.01
>> it is almost there but if i set it to 0 0 2 it is not there any more.
>> I guess it might be because it is either beyond the back limit y or
>> behind the camera?
>> altern(e)k dio:
>>> I am trying to map GEM units to pixels so that i can position some
>>> videos in the GEM window using pixels values. For this I understand that
>>> i must match the projection values with the window size. So i am doing
>>> dimen 400 300
>>> perspect 0 400 0 300 1 20
>>> and i render all objects at z position 1
>>> translateXYZ 100 100 1
>>> However I am getting a weird result, the units are far smaller that
>>> pixels, so to move a video 100px in the x i need to change it x position
>>> by 300 units or something like this. So I am not sure about what i am
>>> doing wrong, I am familiar with OpenGL but i never played too much with
>>> GEM before so I am still getting into it.
>>> Another small issue is that I would also like to reverse the Y so that
>>> upper left is 0,0 and bottom left would be 0,200 for example, not sure
>>> about how to change this. I guess it is to do with the gemwin settings
>>> but i dont get it right.
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