Forums > Jitter

chromatic delay ala vade or "show me the night" video?


cudnylon
Mar 12 2010 | 5:44 pm

trying to come up with some new visual effects and came across these:

http://abstrakt.vade.info/?p=150
http://vids.myspace.com/index.cfm?fuseaction=vids.individual&videoid=102732803 (ignore the music)

any idea of how i can accomplish something like this or at least point me in the right direction?


laserpilot
Mar 15 2010 | 2:52 am

Try using [jit.unpack] to seperate everything out into each individual color plane and then throw a [jit.slide] onto each individual plane.

Frame delay is not the easiest in max unfortunately..but you would have to rig something up with [jit.matrixset] and that nastiness

You can also just use [jit.rota] on each individual color plane to offset it like that music video

then after you do your business on each plane, send it all back into a jit.pack and you’ll be set


cudnylon
Mar 15 2010 | 10:06 am

thanks, that should get me in the right direction.

edit: nope, got a problem. it splits out fine but it’s all monochrome, no color separation. tried the example in the help patch with jit.qt.grab and jit.qt.movie and both didn’t work. only got a color change when i adjusted the scalebias but it was in the combined dumpout of jit.unpack while the split versions it just became whiter or blacker. i’m starting to feel like there is something wrong with jitter on my laptop since a few shaders aren’t working properly either.


laserpilot
Mar 18 2010 | 1:37 pm

well yeah it is certainly all monochrome when it comes out of jit.unpack..the trick is offsetting things and then bringing them all back in via jit.pack then they will be their normal colorful selves again..you can even muck around with swapping color planes as they come back into jit.pack or something..like putting blue into red etc


Joshua Kit Clayton
Mar 18 2010 | 5:48 pm

Here’s a quick demonstration of the concept.



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

cudnylon
Mar 19 2010 | 12:53 am

AMAZING! Thanks for the perfect jumping off point.


laserpilot
Mar 19 2010 | 3:53 pm

Nice. I’d love some tips on how to work with separating the chroma channels in a shader..making an unpack/pack shader that is. i’ve played with the idea a little bit in quartz composer, but haven’t spent enough time with it in max. jit.gl.slab has the potential to spit out multiple outlets/have multiple inlets doesn’t it?


Joshua Kit Clayton
Mar 19 2010 | 5:46 pm

Good question. We don’t provide standard shaders that do this, but I’ve taken the time to whip some up (we’ll probably include in future versions). The basic issue as you point out is that jit.gl.slab doesn’t support multiple outputs. We accomplish that by using four jit.gl.slab objects which each grab a single plane, mapping it to all four planes for a monochrome output. jit.gl.slab does support multiple inputs, so then we can recombine these multiple monochrome input planes to make a single RGBA output matrix.

I’ve uploaded a zip file with example patches and shaders to do this.

A note for the advanced user (beginning users can safely ignore the following without worrying about all the technical jargon):

You could in theory optimize these shaders to pack monochrome information in the color planes, reducing texture size by a factor of 4, using techniques demonstrated in the UYVY and GRGB example shaders. I’ve avoided this for these examples as it further complicates both the shader and potentially any intermediate operation which if anything more than a plane independent pointwise operator will have to take this spatial packing in the planar color vector into account.

Hope this is of use.

Attachments:
  1. slabplanemonopack.zip

laserpilot
Mar 19 2010 | 5:55 pm

Awesome! Definitely not something I would’ve figured out quickly on my own. I’ll play around with it more in a bit, but this looks like what I was gunning for. Thanks


cudnylon
Mar 19 2010 | 9:14 pm

thanks for that. i was hoping for a gpu solution as well. unfortunately it seems like my laptop has stopped working with gl processes (it’s slowly dying, gpu might be shot. not sure what’s wrong exactly) but luckily i’ll be borrowing a friend’s laptop for the performance.


Joshua Kit Clayton
Mar 21 2010 | 7:46 pm

Might try reinstalling your graphics drivers…

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