@woland thanks, this method is cool, for me also quite hard to manage. I ended up using virtual stages for each slice, and then sending each virtual stage to another mapper to do the masking. I prefer this mostly because the mapper interface is much nicer to use for quad warping, i don't have to build a secondary interface for the quad warping as I would with your suggestion (this gets rough with 16 slices and I don't have much time)- overall I think the solution I am using, although heavy (but I suspect without the 3d and ffgl it uses less resources than your example) keeps a pretty useable interface and one that is appropriate for mapping - especially large numbers of pieces.
I think an output mask on the mapper is a pretty valid feature and something that would make this and a few other scenarios I have faced a fair bit easier, Or also having the same blending options that exist in the composite mapper (additive subtractive and invert for all slices) would be great and allow for a lot of cool and fast variations.
Yesterday I had made a similar solution to you creating a kind of fake alpha mask with shapes, it works quite well but it is cumbersome.
To answer this:
"If you've got 16 unique objects at unique angles to map onto, how would you avoid sending content to them separately?"
I only have 7 projectors, so if masking outputs on the mapper were possible I would not need any virtual stages (now I have 16) and I would only need 7 projectors (I now have 32) - my source material is one huge movie file.As for screen capture and re-edit I need a completely flexible workflow, its mapping and will need to be checked and adjusted- the movie takes a long long time to render and I cannot wait 6 hours for masks that will need to be adjusted as the projectors and hanging slices will move a little.
While I was doing this I tried a few other things and wanted to also ask about the logic - if I have an image coming into the mapper that has alpha and I make a rectangle slice in the mapper that only has that alpha, what happens to that alpha- it is pretty much ignored in compositing at the moment, looking at the layer hierarchy logic I should be able to sample a piece of alpha inside the mapper and use it as a "mask" (depending on the layer hierarchy and settings) - this does not seem to be what is happening now, but what is the logic when I sample a piece of alpha material inside the mapper and layer it with other slices?
Fred
