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jit.gl.gridshape to jit.matrix for feedback effect

April 9, 2014 | 1:38 am

Hello,

I would like to "write" the output from a gridshape object in a matrix to process with matrix tools then create a feedback effect. I tried Peter Elsea’s patch with the matrixoutput set to 1 but it doesn’t work and so does the feedback loop. The idea would be to work on textures over a movie background.
Here’s the simple patch :

– Pasted Max Patch, click to expand. –

Thanks for your help !

  • This topic was modified 5 months by  nakatano.
  • This topic was modified 5 months by  nakatano.

April 9, 2014 | 8:57 am

sorry, it’s not clear what you are trying to do.
it looks like your mixing geometry matrices (those emanating from a gl.gridshape) with image matrices (from qt.movie or other source).

the dimensions, planecount and type of these matrix sources are usually very different and incompatible.


April 10, 2014 | 12:39 am

Hello Rob,

well, that’s more or less what I thought. This patch is just a simplified part of a much bigger patch where I use a lot the fourth argument of the erase_color (1. 1. 1.and 0. to 1. for the 4th number) attribute of the jit.render object to create some "blur" or "feedback".
The visual artist I work with would like to project the "sound-altered" moving pictures (see : http://nicolascanot.tumblr.com/ for an idea of the pictures) produced by this patch, superimposed on fixed pictures (prepared photographs in Photoshop/InDesign) using only one VP.
The problem is that, when doing so (which works when using the videoplane + alphablend objects), the "erase_color feedback" doesn’t work anymore so I try to find some solutions to create feedback in the patch "before" the "GL picture" is mixed with the photographs.
Maybe the solution is simply to use two VPs unless there’s some solutions to remove the (white, in this case) background of the jit.render object (I mean, working with transparencies) while keeping the erase_color 4th attribute functional (which seems contradictory !).

Not sure it’s more clear now but it’s not easy to explain…


April 10, 2014 | 9:38 am

you can overlay two textures by creating to jit.gl.videoplanes @depth_enable 0 @blend_enable 1
you control the order with the @layer attribute.

you can change the blend technique with the @blend attribute.

check out the following example patch that demonstrates how to use gl.node and jit.gl.pix to create the erase_color smearing trick with a captured texture:
Max 6.1/examples/jitter-examples/gen/smear.o.vision.maxpat


April 10, 2014 | 10:32 am

It looks like the perfect tool !!
Just have to modify the patch from the beginning now…

Thanks Rob !


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