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switch variable: $colscale -- funct color scale
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switch value: 0 => RBG wheel1 (complex data)

The "w1" (wheel1) color scale is designed for
phase-encoded data (e.g., retinotopic mapping).

Eccentricity maps

With $angle_cycles=1.0, the scale is
red->blu->grn wrapping back through dark yellow
to red (each phase will have a unique color).
Higher integer numbers result in multiple passes
through the color wheel for one cycle of phase.

Polar angle maps (hemifield)

With non-integral $angle_cycles there is only one
red->blu->grn cycle.  Phase values below full red
are clamped to red and phase values above full
green clamped to green.  Higher non-integer
values of $angle cycles (e.g., 3.9) compress
range between full red and full green (i.e., less
blue).  The clamped red and green fade to gray
for ipsiliateral phases (180 deg away from blue)
as controlled by $fadef (1.0=no fade,
0.7=default, smaller for more fade).

Ipsilateral phases can be colored yellow instead
of gray by setting "iy:" ($ipsiyellowfact) to a
non-zero value (from 0.0001 to 1.0).

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Alt (mid-click): shortcut to get "w2" w/o fn-F3
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Middle-clicking the "w1" button switches to the
"w2" RYGB wheel (colscale=8) without having to
use the extended (fn-F3) panel.  See the
right-click help for "w2" on the fn-F3 panel for
details of that color scale.

