star_scale {gridpattern} | R Documentation |
Compute regular star polygon scale or angles
Description
star_scale()
computes star scale
value given
an internal or external angle. star_angle()
computes
star angle (internal or external) given a scale
value.
Usage
star_scale(n_vertices, angle, external = FALSE)
star_angle(n_vertices, scale, external = FALSE)
Arguments
n_vertices |
Number of exterior vertices. |
angle |
Angle in degrees. |
external |
If |
scale |
Scale from 0 to 1. |
Details
grid.pattern_regular_polygon()
parameterizes regular star polygons
with the number of its external vertices and a scale
that equals the
fraction of the radius of the circle that circumscribes the interior vertices
divided by the radius of the circle that circumscribes the exterior vertices.
These helper functions help convert between that parameterization
and either the internal or external angle of the regular star polygon.
Value
star_scale()
returns a numeric value between 0 and 1 intended
for use as the scale
argument in grid.pattern_regular_polygon()
.
star_angle()
returns a numeric value between 0 and 360 (degrees).
Examples
# |8/3| star has internal angle 45 degrees and external angle 90 degrees
scale <- star_scale(8, 45)
scale2 <- star_scale(8, 90, external = TRUE)
all.equal(scale, scale2)
star_angle(8, scale)
star_angle(8, scale, external = TRUE)
grid.pattern_regular_polygon(shape = "star8", scale = scale, angle = 0,
spacing = 0.2, density = 0.8)