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Jitter and Text over gl/w camera change

March 31, 2006 | 9:03 pm

Hi All:

A new guy on the block here…

I am working on a project that take video in, uses it as a texture over a (plato) shape- rendering ultimately to a jit.window. I am using Cyclops as the input for control of color and motion. Here’s where I’m in need of your help…

How does one put text over the video, and NOT have the text change in relation to the plane of the rotated camera view? In other words, I want to keep the text (title of the work) in the same place (videoplane example as AndrewB was so kind to share with us) while allowing the gl moves to move the shape via the "camera" and "pak lookat" numbers?

Any suggestions?

Thanks,
Kevin


March 31, 2006 | 9:50 pm

Hi Kevin,

check out this post : http://www.cycling74.com/forums/index.php?t=msg&th=19058 &start=0&rid=1274&S=f84caaec3afd8b35d25704e948d4 b22a
It has a nice tutorial by vade explaining the principle. In the patch two black bars are rendered on top of the geometry, but the way this is done also works in the same way with jit.gl.2dtext (or 3dtext)


March 31, 2006 | 10:16 pm

Thanks… I will study these two… much appreciated.


April 1, 2006 | 5:15 pm

Hello Kevin,

if the only shape you have in your scene (apart form the text)
you might as well just rotate the shape, instead of moving the camera.
if there is more than one shape, it is still true that camera movements
may be substituted by movements of the shapes in your scene, but
there would
be little advantage regarding ease of programming.
HtH
-jennek


April 1, 2006 | 5:29 pm

you have to reset your camera position before you draw your text.

basically, use @automatic 0 for all of your rendering, and force a
specific drawing order

ie in some pseudo basic:

0 erase to jit.gl.render
10 set camera position to where we want to be rotated
20 draw object that you want behind
30 draw object that you want in front (opengl draws back to front…
if you dont have depth_enable 1 and a depthbuffer 1 on
jit.gl.window.. ;)
40 set camera to origin (position 0. 0. 2, lookat 0. 0. 0. to
jit.gl.render)
50 draw jit.gl.text2d or 3d
60 send bang to jit.gl.render to actually ‘draw’ to the render context
70 goto 0

this is really a much ‘cleaner’ way of doing it, as you can use it as
a prototype and ‘drop’ any other GL objects in there and all will
behave as expected, and you can separate your render chain to before
rotation and after, so you can, if you wish, add your own little
watermark to the lower left hand corner in GL, overlay another
jit.gl.videoplane with an alpha channel over your whole animation,
etc etc.

check Brechts post, he points to a patch he made that does it, and to
one that I made. Both use the same exact principle. Sorry if im
repeating myself ;)

v a d e //

http://www.vade.info
abstrakt.vade.info

I LIVE! I LIVE! I LIVE! I LIVE! I LIVE! I LIVE! I LIVE! I LIVE! I
LIVE! I LIVE! I LIVE! I LIVE!

You will not be saved by the Holy Ghost. You will not be saved by the
God Plutonium.

In fact, YOU WILL NOT BE SAVED!


April 3, 2006 | 2:30 pm

Yes! Thank you! That did it. Your clarity and help are much appreciated!


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