Fun with FX:   Exploring Eos hue effects

    [Originally sent to the "stagecraft" list, but seemed worth
    subsequently turning into a more permanent page]
Date: Wed, 27 Mar 2019 14:27:07 -0500
Subject: some Eos display fun

Long, but fun for the Eos/Ion/whatever nerds...

At an event last weekend we had an ETC Element, and a row of LED bars for cyc lights.  The LD chose to chunk up the bars as fine-grained as they could go in terms of addressing, so we effectively had 72 separate RGB units firing straight up the cyc to facilitate higher-resolution color effects.

The obvious thing to mess with was the built-in RGB rainbow chase, which did the expected thing -- one big spectrum spread scrolling across the backdrop, which was entertaining but got old rather quickly.  Selecting all channels for the "units" in this state placed their color output representations on the CIE color chart in the ML-controls display, as a dense gray ring -- as each of 72 dots was only slightly displaced from its neighbor as they all wandered around the hue circle.

I wanted something more interesting and with a little more visual separation, so selected the units with offset "random" and 11 groups instead of 72 to address wider stripes across the cyc.  This brought up a circle of 11 dots on the CIE, with some units on top of each other from the grouping, but still all looping around the hue with the same effect rate.

    Dots in a circle representing hue states

Now, the way the built-in profiles for LED units work is to hold all color values at 100 as the home state, such that bringing up intensity gives white at first.  I like composing cyc colors with a trio of sliders, rather than mouse-poking at a color wheel.  Rather than copying the fixture type and changing all the home values to 0 like I did last time, thus enabling mixing in straight RGB, I left the profile alone and had submasters to bring each color *to zero* as its slider went up.  Thus, I effectively had CMY mixing instead, which is simply RGB turned upside down.  This is valid because a submaster controlling any non-intensity stuff is basically an LTP *execution* scenario, not an HTP addition.  The board can really bite you in the ass if you don't keep thinking about it that way, and there is no option [other than using inhibits, perhaps] to make that not so.

So for straight-up composition I had four sliders -- cyc intensity, and the three "get rid of color" subs.  The main show got cued up using that.  I then threw my random-groups effect onto another sub, just to bring up as desired.  That FX sub contained color only; I still had independent control of actual cyc brightness with the fake-intensity sub.  What then became really fascinating was the interaction between all of these, more so on the board's monitor than the cyc itself, and I took a short sample video.     [3Mb, 0:43]

The FX sub controls the size of the circle, i.e. the depth of the effect.  The video also starts with the "remove blue" sub just barely asserted off the bottom -- the circle is a flattened oval instead, perpendicular to the blue axis, and the more I bring up my "remove blue" sub up the farther away from the blue corner it moves.  At about 8 seconds, the blue sub de-asserts when pulled down to 0 and suddenly the circle is a circle again.  That's not a smooth transition for some reason.  Yes, this was visible on the cyc as a color jump but not obnoxiously so.  Whichever "remove color" sub comes off 0 most recently is the one that takes over and pushes the circle around, as we'd sort of expect.  From there I play with the other not-colors, FX size, etc and the results are pretty amusing.  When two color-remove sliders are asserted and raised, the circle flattens to a line and dives into the corner for the only color left.

    Bad shot of effect on cyc

Since all this was basically for a house open walk-in at a low level, it was just for some "oh, the techs are having fun" audience entertainment.

_H*   190327