Forums > Jitter

alphamask shader


Sophia
Jan 26 2010 | 1:48 am

Kinda dumb question, but is there a shader to create alpha masks?

Like this:

— Pasted Max Patch, click to expand. —

The lack of a shader reference is killing me!


Rob Ramirez
Jan 26 2010 | 4:44 am

Max5/Cycling ’74/jitter-shaders/color/cc.alphaglue.jxs
Max5/Cycling ’74/jitter-shaders/composite/co.alphablend.jxs
are the two to check out. alphaglue will create an alpha channel based on luminance.
alphablend works similar to jit.alphablend (expects the source textures to have an alpha channel).

Max5/examples/jitter-examples/render/slab-helpers/color/cc.alphaglue.jxs-help.maxpat
Max5/examples/jitter-examples/render/slab/jit.gl.slab-composite.maxpat
should will help you out with these shaders.


Sophia
Jan 27 2010 | 1:22 am

Thanks, Rob. Alphaglue does the trick without even adjusting the parameters!

As far as references, I wasn’t talking about help files as most of the shaders are very self explanatory. I just meant some kind of list that tells you what each one does. I know cv.jit has an object guide and Peter Elsea put together a reference for regular jitter effects, with screenshots even. I never understood why there wasn’t one for the shaders. The slab compositing example serves some of that purpose and I’m sure I’ll find more like that if I poke around in the examples folder.


Sophia
Jan 29 2010 | 1:12 am

Is there a way to get alphaglue to work in jit.gl.shader, similar to sending the same texture to both inlets of a slab? I’m trying to implement this in the poly~ abstraction you recommended in my other thread and using slabs is much more annoying.


Sophia
Jan 31 2010 | 9:52 pm

Still having a ton of trouble with this. Here is the patch:

— Pasted Max Patch, click to expand. —

And the poly~ abstraction:

— Pasted Max Patch, click to expand. —

Sophia
Feb 09 2010 | 12:34 am

Still struggling. It seems the shaders aren’t attaching now.

Here is the most recent version:

— Pasted Max Patch, click to expand. —

— Pasted Max Patch, click to expand. —

Rob Ramirez
Feb 09 2010 | 2:26 am

not really sure what you are trying to do, but see if this patch helps you out.
basically, we use the alphaglue shader to create an alpha channel based on luminance, and we composite our videoplanes using blend_enable 1 (which requires depth_enable 0 to work properly).



-- Pasted Max  Patch, click to expand. --

Sophia
Feb 09 2010 | 11:46 pm

I actually realized that Andrew Benson’s lumagate shader from his "Your First Shader" article does exactly what I need, so I substituted that for the alphaglue. I am trying to run both that and a radial blur from jit.gl.shader, rather than slabs, for ease in the poly~ abstraction. Unfortunately, it appears that neither of my shaders is binding correctly.

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Forums > Jitter