David Beaudry

I don't know why I am having such a block against this, but I am. Here's what I am trying to do.

#2 = live feed of a performer in black & white (binary image)

Goal: whatever is white in the live feed (#2) becomes a window to the texture (#3). Whatever is black in the live feed becomes transparent and shows the background image (#1).

I'm trying to do everything I can in gl using jit.gl.videoplane for the mixing/blending.

I've been able to get the first part to work without a problem...however I'm am really not sure if the blend modes I am using are right. To get the live feed to be filled with the texture I have the texture set to layer 2, blendmode = 1 0. The live feed is layer 3, blend mode 0 3. Don't know if that is right, but it works up to this point. I have the background set to layer 1, and it just doesn't matter what blendmode I use, nothing shows up (not surprising). I'm pretty certain what I need to do is create an alpha channel to the live feed...whenever the image is white alpha = 1., black alpha = 0. I started on this, but I think my lack of understanding of blend_modes is going to keep me from seeing any results.

I know a patch will be helpful and am working on one now to follow-up with, but if anyone has any pointers in the meantime, it would be hugely appreciated.

Hi all,
I don't know why I am having such a block against this, but I am. Here's what I am trying to do.

I have three videoplanes:
#1 = background image
#2 = live feed of a performer in black & white (binary image)
#3 = texture to be applied to performer

Goal: whatever is white in the live feed (#2) becomes a window to the texture (#3). Whatever is black in the live feed becomes transparent and shows the background image (#1). 

blend-modes-layers-and-me

hi david. i think a custom shader would be the best solution.

the glsl mix function should do everything you need.

hi david. i think a custom shader would be the best solution.
the glsl mix function should do everything you need.

This is perfect. Thank you for your help with this!

Rob, you are my new best friend :)
This is perfect. Thank you for your help with this!

Perhaps I haven't thought this thru very well, but how would I preserve the alpha channel of the two textures being mixed in, e.g. if the texture I am using to replace black has an alpha mask, is there a way to preserve it?

Reviving an old thread here!
Perhaps I haven't thought this thru very well, but how would I preserve the alpha channel of the two textures being mixed in, e.g. if the texture I am using to replace black has an alpha mask, is there a way to preserve it?

In Max6 if you are capturing the texture via jit.gl.node you can specify node's @erase_color as 0 0 0 0 and the alpha channel will be preserved.

That's something that can be adjusted in the shader.

These two lines:
vec3 mixr = mix(b.rgb,c.rgb,a.rgb);
gl_FragColor = vec4(mixr,1.);

…can become:
vec4 mixr = mix(b,c,a.g);
gl_FragColor = mixr;

blend modes, layers, and me