Blend a slab / videoplane and a qt movie?

heaversm's icon

Hi - I have a slab that is combining the output of syphon with a qt movie. I then want to alpha blend the result of this with another qt movie that will lay over the top and show the slab (syphon + qt) beneath using the alpha channel of the movie. I have the patch that renders the slab, and renders the qt movie, I just can't seem to find out how to combine the two.

5181.chromakeyvideo.maxpat
Max Patch
mattyo's icon
Max Patch
Copy patch and select New From Clipboard in Max.

you just have to chromakey the results of your first chromakey with another:

heaversm's icon

Is there a way to do this with an alphablend and not a second chromakey? Doing two chromakey operations doesn't seem to behave the way I want. All I want to do is have my video with alpha play over the top of my blended slab video.

LSka's icon

Why not use another slab with the co.alphablend.jxs shader?
There's also a jit.gl.pix solution for alphablend unside the jitter-examples folder

mattyo's icon

Oh, I got it. What you want to do is put your video with the alpha on a videoplane that renders on top of you background video, using the @layer attribute, and setting blend_enable to 1 on your videoplanes. See attached.

Max Patch
Copy patch and select New From Clipboard in Max.

M