[PD] GEM mapping units to pixels

altern altern2 at gmail.com
Sat May 12 11:09:42 CEST 2007

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:
> hi
> 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.
> thanks
> enrike

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