[PD] GEM mapping units to pixels

Sun May 13 19:41:28 CEST 2007

Your example patch works exactly as it should on OSX.

On 5/13/07, altern <altern2 at gmail.com> wrote:
>
> cyrille henry(e)k dio:
> > hello,
> >
> > altern a écrit :
> >> hi
> >>
> >> do you mean something like the example attached?
> > yes, exactly.
> >
> >> This doesnt work ok for me, the shape should be 10x10 px and is not,
> > a [rectangle 10 10] should be 20 pixel.
>
> i understand from the rectangle help that [rectangle 10 10] should be a
> 10 units width by 10 units height square. I get a rectangle which is
> irregular, check the attached screnshot gif
>
> >> 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
> > translating to 400 300 should move the center of the rectangle in the
> > top right corner.
> > if your rectangle is 100 100, then you just have to move it 300 200 in
> > order to have the corner of the rectangle in the corner of the gem
> window.
> >
> > your patch work that way here.
>
> check the attachment again, the rect is 10x10 and it is located at
> X=307, Y=167. This should be far from 400, 300 which should be the
> top,right location. So the coordinate system is distorted, specially on
> the y axis
>
> I also tried with
> dimen 400 400
> perspec 0 400 0 400 999 1001
> If draw a 1 by 1 rect and i get it to the right top corner by
> translating it 320, 320. So pixels are dont match gl units and moreover
> in the previous example when the gem window is not a square the
> distortion affects differently the X and the Y axis
>
> >>
> >> 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?
> > yes, insert an [ortho] after the gemhead
> >
> >
> > cyrille
> >
> >>
> >> thanks!!
> >>
> >> enrike
> >>
> >> cyrille henry(e)k dio:
> >>> hello,
> >>>
> >>> 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.
> >>>
> >>> cyrille
> >>>
> >>>
> >>> 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?
> >>>>
> >>>> thanks
> >>>>
> >>>> enrike
> >>>>
> >>>>
> >>>> 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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> >>>> UNSUBSCRIBE and account-management ->
> >>>> http://lists.puredata.info/listinfo/pd-list
> >>>>
> >>>>
> >>>
> >>
> >>
> >>
> >>
> ------------------------------------------------------------------------
> >>
> >> #N canvas 393 156 429 320 10;
> >> #X obj 84 210 gemwin;
> >> #X obj 245 163 gemhead;
> >> #X msg 173 82 create \, 1;
> >> #X msg 293 106 0 \, destroy;
> >> #X floatatom 309 164 5 0 0 0 - - -;
> >> #X floatatom 347 164 5 0 0 0 - - -;
> >> #X floatatom 288 215 5 0 0 0 - - -;
> >> #X floatatom 332 215 5 0 0 0 - - -;
> >> #X obj 245 190 translateXYZ 10 10 1;
> >> #X msg 215 50 dimen 400 300;
> >> #X msg 48 73 view 0 0 1000;
> >> #X msg 9 48 perspec 0 400 0 300 999 1001;
> >> #X msg 110 99 reset;
> >> #X obj 50 -8 bng 15 250 50 0 empty empty empty 0 -6 0 10 -262144 -1
> >> -1;
> >> #X obj 50 13 t b b b b b;
> >> #X obj 245 234 rectangle 10 10;
> >> #X connect 1 0 8 0;
> >> #X connect 2 0 0 0;
> >> #X connect 3 0 0 0;
> >> #X connect 4 0 8 1;
> >> #X connect 5 0 8 2;
> >> #X connect 6 0 15 1;
> >> #X connect 7 0 15 2;
> >> #X connect 8 0 15 0;
> >> #X connect 9 0 0 0;
> >> #X connect 10 0 0 0;
> >> #X connect 11 0 0 0;
> >> #X connect 12 0 0 0;
> >> #X connect 13 0 14 0;
> >> #X connect 14 0 11 0;
> >> #X connect 14 1 10 0;
> >> #X connect 14 2 12 0;
> >> #X connect 14 3 2 0;
> >> #X connect 14 4 9 0;
> >>
> >
>
>
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>
>
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