Hi Ben

Why not:

a. texture a large plane with a circular alpha channel hole

b. model a large plane with a circular hole.

I'll give that a try, I think i'll need some more flexibility since i need to have other polygons in the same patch... but maybe i can solve it in a different way...

Both would be a mask that show through what is rendered behind them, should be very fast, but not as flexible, as your ideas.

Being fast is definitely going to be a requirement. Now, in this context, is flexibility a synonym for madness? or more precisely, is this approach too slow?

best,

J

.b.

Jaime Oliver wrote:

...

Hello all, I am trying to do something which should be fairly easy: I am trying to see a circle that let's through an image that is behind it. (As if through a telescope...) So my attempt so far consists of texturing this image into a circle and compensate changes in translation and size of the circle with the pix_coordinate object. I have managed to do this with rectangles and triangles, but can't a find a way around circles. The main idea is the next:

pix_image | pix_texture coordinate-mess | / pix_coordinate | rotateXYZ | translateXYZ | circle

The coordinate message has this behaviour: -the 1st two floats don't have any effect. -the 3rd one compresses/expands left-right, -the 4th one compresses/expands up-down, -the 5th doesn't do anything, -the 6th one seems to offest the vertical compression/expanssion -any succesive floats have no effect.

So my problem is that without any horixontal offest i can't compensate for size/transaltion values. If i had that i think i could do some math to do this....

Anyone has any suggestions? Is this the wrong approach??

I am attaching the patch if anyone want's to test this and I am also attaching an example of how i am compensating this for a polygon 3

best,

J

-- Jaime E Oliver LR

joliverl@ucsd.edu mailto:joliverl@ucsd.edu www.realidadvisual.org/jaimeoliver http://www.realidadvisual.org/jaimeoliver www-crca.ucsd.edu/ http://www-crca.ucsd.edu/ www.realidadvisual.org http://www.realidadvisual.org

9168 Regents Rd. Apt. G La Jolla, CA 92037 USA

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[disk] will give you this kind of bagel shape.

Am 25.03.2008 um 16:49 schrieb Oded Ben-Tal:

...

Hello all, I am trying to do something which should be fairly
easy: I am trying to see a circle that let's through an image that is behind
it. (As if through a telescope...)

Why not render the picture on a square/rectangle, and put a 'hole' in front of it (for instance a cylinder: make it very wide, thick, and short. rotate 90 degrees so we are looking 'throught' it). moving the picture & your 'hole' in coordinated fashion back and forth could
create a telescope like effect, no?

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