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entry variable: $angle_cycles -- adjust phase colscale
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default: 2.2

The "anglecycles:" entry (lower right) controls
the spacing of colors around phase color wheels.

Integral values of $angle_cycles (1,2,3) result
in one or more red-green-blue/magenta wraps of
across 360 deg of phase.

Non-integral values of $angle_cycles result in a
single green-blue-red cycle.  For example,
$angle_cycles 2.2 results in a slightly more
rapid change between green-blue-red then with
2.01 cycles per 360 degrees.  By contrast,
$angle_cycles 1.4 results in a more spread-out
green-blue-red cycle.

Larger, non-integral $angle_cycles (e.g.,
$angle_cycles 3.1) squeeze the green-blue-red
transition even tighter, which can be useful for
cross-subject average data where the range of
phases is compressed as a result of slight
spatial misalignments of averaged maps.

Phases just beyond either end of the single pass
through green-blue-red are initially clamped to
the end colors (red or green), and then at
greater angular distances eventually fade to gray
at phases opposite to the center color (blue).

The effects of different $angle_cycles are best
seen by clicking "disk" at the upper right to get
a color wheel inset.

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Cortex-position-dep adjustments for average data
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As visual areas get smaller, which is generally
correlated with being more anterior in the brain,
there is a tendency to 'regress to the horizontal
meridian' because of slight between-subject
offets in the location and orientation of smaller
areas.

More anterior maps are also more likely to
demonstrate eye position-dependent maps (e.g.,
VIP) which can systematically displace the polar
angle of receptive fields.

These effects can be compensated in a tcl script
using the C/tcl function (not currently exposed
in the interface):

  linrampphase2vtxcol <aoff1> <acyc1> <aoff2> <acyc2>

First click twice on a folded, inflated, or
flattened surface.  The first click defines the
beginning of the ramp and the second click, the
end.  A linear ramp in angle_offset and
angle_cycles is applied along the line between
the two clicks, with modification isocontours
perpendicular to that line.  The value of
angle_offset and angle_cycles beyond the ends of
two-click line segment are flat, clamped to the
values specified above.

This sets the vertex color (vtxcol) fields for
the entire brain.  Use middle-click "CLR" on the
"label:" line to clear the vertex colors (which
will reveal the standard color scale colors
underneath.  Or to toggle between the original
and the vtxcol "paint", toggle vtxcolflag
(available in R-click help popup from far left
tickbox on "label:" line).

The result can be saved to .tiff or .rgb like any
other rendering.

To save the vtxcol "paint", use ctrl-right-W on
the "label:" line (tclfunct: write_vtxcol_label).

Currently, this command does not accept phase
wraps in angle_offset, so if you want to make a
ramp between an angle_offset of 0.98 and 0.03,
use 0.98 and 1.03 instead.

