cgalPolygon: R6 class to represent a CGAL polygon
In cgalPolygons: R6 Based Utilities for Polygons using 'CGAL'
cgalPolygon R Documentation
R6 class to represent a CGAL polygon
Description
R6 class to represent a CGAL polygon.
Methods
Public methods
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Method new()
Creates a new cgalpolygon object.
Usage
cgalPolygon$new(vertices)
Arguments
verticesa numeric matrix with two columns
Returns
A cgalPolygon object.
Examples
library(cgalPolygons)
ptg <- cgalPolygon$new(pentagram)
ptg
Method print()
Print the cgalPolygon object.
Usage
cgalPolygon$print(...)
Arguments
...ignored
Returns
No value, just prints some information about the polygon.
Method area()
Signed area of the polygon.
Usage
cgalPolygon$area()
Returns
A number, the signed area of the polygon; it is positive if the
polygon is counter-clockwise oriented, negative otherwise.
Examples
library(cgalPolygons)
ptg <- cgalPolygon$new(pentagram)
ptg$area() # should be 5 / sqrt(130 + 58*sqrt(5))
5 / sqrt(130 + 58*sqrt(5))
Method boundingBox()
Bounding box of the polygon.
Usage
cgalPolygon$boundingBox()
Returns
A 2x2 matrix giving the lower corner of the bounding box in its
first row and the upper corner in its second row.
Examples
library(cgalPolygons)
ptg <- cgalPolygon$new(pentagram)
plot(ptg$boundingBox(), asp = 1)
polygon(pentagram)
Method convexParts()
Decomposition into convex parts. The polygon must be simple
and counter-clockwise oriented.
Usage
cgalPolygon$convexParts(method = "optimal")
Arguments
methodthe method used: "approx", "greene",
or "optimal"
Returns
A list of matrices; each matrix has two columns and represents
a convex polygon.
Examples
library(cgalPolygons)
ptg <- cgalPolygon$new(pentagram)
cxparts <- ptg$convexParts()
ptg$plot(col = "yellow", lwd = 3)
invisible(
lapply(cxparts, function(cxpart) {
polygon(cxpart, lwd = 2)
})
)
Method getVertices()
Vertices of the polygon.
Usage
cgalPolygon$getVertices()
Returns
The vertices in a matrix with two columns.
Examples
library(cgalPolygons)
ptg <- cgalPolygon$new(pentagram)
ptg$getVertices()
Method intersection()
Intersection of the polygon with another polygon.
Usage
cgalPolygon$intersection(plg2)
Arguments
plg2a cgalPolygon object or a cgalPolygonWithHoles
object
Returns
A list whose each element is either a cgalPolygon object
or a cgalPolygonWithHoles object.
Examples
library(cgalPolygons)
# function creating a circle
circle <- function(x, y, r) {
t <- seq(0, 2, length.out = 100)[-1L]
t(c(x, y) + r * rbind(cospi(t), sinpi(t)))
}
# take two circles
plg1 <- cgalPolygon$new(circle(-1, 0, 1.25))
plg2 <- cgalPolygon$new(circle(1, 0, 1.25))
# intersection
plgList <- plg1$intersection(plg2)
plg <- plgList[[1L]]
# plot
opar <- par(mar = c(0, 0, 0, 0))
plot(
NULL, xlim = c(-2.6, 2.6), ylim = c(-1.3, 1.3), asp = 1,
xlab = NA, ylab = NA, axes = FALSE
)
plg1$plot(lwd = 2, new = FALSE)
plg2$plot(lwd = 2, new = FALSE)
plg$plot(lwd = 3, col = "red", new = FALSE)
par(opar)
Method isCWO()
Checks whether the polygon is clockwise oriented.
Usage
cgalPolygon$isCWO()
Returns
A Boolean value.
Examples
library(cgalPolygons)
ptg <- cgalPolygon$new(pentagram)
ptg$isCWO()
Method isCCWO()
Checks whether the polygon is counter-clockwise oriented.
Usage
cgalPolygon$isCCWO()
Returns
A Boolean value.
Examples
library(cgalPolygons)
ptg <- cgalPolygon$new(pentagram)
ptg$isCCWO()
Method isConvex()
Checks whether the polygon is convex.
Usage
cgalPolygon$isConvex()
Returns
A Boolean value.
Examples
library(cgalPolygons)
ptg <- cgalPolygon$new(pentagram)
ptg$isConvex()
Method isSimple()
Checks whether the polygon is simple; that means its edges
do not intersect (except two consecutive edges which intersect at
their common vertex)
Usage
cgalPolygon$isSimple()
Returns
A Boolean value.
Examples
library(cgalPolygons)
ptg <- cgalPolygon$new(pentagram)
ptg$isSimple()
Method minkowskiSum()
Minkowski sum of the polygon and another polygon.
Usage
cgalPolygon$minkowskiSum(plg2)
Arguments
plg2a cgalPolygon object or a cgalPolygonWithHoles
object, the polygon to add to the reference polygon
Returns
Either a cgalPolygonWithHoles object, or, in the case if
there is no hole in the Minkowski sum, a cgalPolygon object.
Examples
library(cgalPolygons)
plg1 <- cgalPolygon$new(decagram)
plg2 <- cgalPolygon$new(star)
minko <- plg1$minkowskiSum(plg2)
minko$plot(lwd = 2, col = "yellowgreen")
Method plot()
Plot the polygon.
Usage
cgalPolygon$plot(..., new = TRUE)
Arguments
...arguments passed to polygon
newBoolean, whether to create a new plot
Returns
No returned value, called for side-effect.
Examples
library(cgalPolygons)
ptg <- cgalPolygon$new(pentagram)
ptg$plot(lwd = 3, col = "red")
Method reverseOrientation()
Reverse the orientation of the polygon.
Usage
cgalPolygon$reverseOrientation()
Returns
The cgalPolygon object, invisibly.
Examples
library(cgalPolygons)
ptg <- cgalPolygon$new(pentagram)
ptg$isCCWO()
ptg$reverseOrientation()
ptg$isCCWO()
Method subtract()
Difference between the polygon and another polygon.
Usage
cgalPolygon$subtract(plg2)
Arguments
plg2a cgalPolygon object or a cgalPolygonWithHoles
object
Returns
A list whose each element is either a cgalPolygon object
or a cgalPolygonWithHoles object.
Examples
library(cgalPolygons)
# function creating a circle
circle <- function(x, y, r) {
t <- seq(0, 2, length.out = 100)[-1L]
t(c(x, y) + r * rbind(cospi(t), sinpi(t)))
}
# take two circles
plg1 <- cgalPolygon$new(circle(-1, 0, 1.25))
plg2 <- cgalPolygon$new(circle(1, 0, 1.25))
# difference
plgList <- plg1$subtract(plg2)
plg <- plgList[[1L]]
# plot
opar <- par(mar = c(0, 0, 0, 0))
plot(
NULL, xlim = c(-2.6, 2.6), ylim = c(-1.3, 1.3), asp = 1,
xlab = NA, ylab = NA, axes = FALSE
)
plg1$plot(lwd = 2, new = FALSE)
plg2$plot(lwd = 2, new = FALSE)
plg$plot(lwd = 3, col = "red", new = FALSE)
par(opar)
Method symdiff()
Symmetric difference of the polygon and another polygon.
Usage
cgalPolygon$symdiff(plg2)
Arguments
plg2a cgalPolygon object or a cgalPolygonWithHoles
object
Returns
A list whose each element is either a cgalPolygon object
or a cgalPolygonWithHoles object.
Examples
library(cgalPolygons)
# function creating a circle
circle <- function(x, y, r) {
t <- seq(0, 2, length.out = 100)[-1L]
t(c(x, y) + r * rbind(cospi(t), sinpi(t)))
}
# take two circles
plg1 <- cgalPolygon$new(circle(-1, 0, 1.25))
plg2 <- cgalPolygon$new(circle(1, 0, 1.25))
# symmetric difference
plgList <- plg1$symdiff(plg2)
plg <- plgList[[1L]]
# plot
opar <- par(mar = c(0, 0, 0, 0))
plot(
NULL, xlim = c(-2.6, 2.6), ylim = c(-1.3, 1.3), asp = 1,
xlab = NA, ylab = NA, axes = FALSE
)
plg1$plot(lwd = 2, new = FALSE)
plg2$plot(lwd = 2, new = FALSE)
plg$plot(list(lwd = 3, col = "red"), col = "white", new = FALSE)
par(opar)
Method union()
Union of the polygon with another polygon.
Usage
cgalPolygon$union(plg2)
Arguments
plg2a cgalPolygon object or a cgalPolygonWithHoles
object
Returns
A list whose each element is either a cgalPolygon object
or a cgalPolygonWithHoles object.
Examples
library(cgalPolygons)
# function creating a circle
circle <- function(x, y, r) {
t <- seq(0, 2, length.out = 100)[-1L]
t(c(x, y) + r * rbind(cospi(t), sinpi(t)))
}
# take two circles
plg1 <- cgalPolygon$new(circle(-1, 0, 1.25))
plg2 <- cgalPolygon$new(circle(1, 0, 1.25))
# union
plgList <- plg1$union(plg2)
plg <- plgList[[1L]]
# plot
opar <- par(mar = c(0, 0, 0, 0))
plot(
NULL, xlim = c(-2.6, 2.6), ylim = c(-1.3, 1.3), asp = 1,
xlab = NA, ylab = NA, axes = FALSE
)
plg1$plot(lwd = 2, new = FALSE)
plg2$plot(lwd = 2, new = FALSE)
plg$plot(lwd = 3, col = "red", new = FALSE)
par(opar)
Method whereIs()
Locate point(s) with respect to the polygon. The polygon
must be simple.
Usage
cgalPolygon$whereIs(points)
Arguments
pointsa numeric matrix with two columns, or a numeric vector
of length 2 (for a single point)
Returns
An integer vector with possible values -1, 1, or
0: value -1 for outside, 1 for inside, and
0 if the point is on the boundary of the polygon.
Examples
library(cgalPolygons)
ptg <- cgalPolygon$new(pentagram)
pt1 <- c(0, 0) # inside
pt2 <- c(4, 0) # outside
ptg$whereIs(rbind(pt1, pt2))
Examples
## ------------------------------------------------
## Method `cgalPolygon$new`
## ------------------------------------------------
library(cgalPolygons)
ptg <- cgalPolygon$new(pentagram)
ptg
## ------------------------------------------------
## Method `cgalPolygon$area`
## ------------------------------------------------
library(cgalPolygons)
ptg <- cgalPolygon$new(pentagram)
ptg$area() # should be 5 / sqrt(130 + 58*sqrt(5))
5 / sqrt(130 + 58*sqrt(5))
## ------------------------------------------------
## Method `cgalPolygon$boundingBox`
## ------------------------------------------------
library(cgalPolygons)
ptg <- cgalPolygon$new(pentagram)
plot(ptg$boundingBox(), asp = 1)
polygon(pentagram)
## ------------------------------------------------
## Method `cgalPolygon$convexParts`
## ------------------------------------------------
library(cgalPolygons)
ptg <- cgalPolygon$new(pentagram)
cxparts <- ptg$convexParts()
ptg$plot(col = "yellow", lwd = 3)
invisible(
lapply(cxparts, function(cxpart) {
polygon(cxpart, lwd = 2)
})
)
## ------------------------------------------------
## Method `cgalPolygon$getVertices`
## ------------------------------------------------
library(cgalPolygons)
ptg <- cgalPolygon$new(pentagram)
ptg$getVertices()
## ------------------------------------------------
## Method `cgalPolygon$intersection`
## ------------------------------------------------
library(cgalPolygons)
# function creating a circle
circle <- function(x, y, r) {
t <- seq(0, 2, length.out = 100)[-1L]
t(c(x, y) + r * rbind(cospi(t), sinpi(t)))
}
# take two circles
plg1 <- cgalPolygon$new(circle(-1, 0, 1.25))
plg2 <- cgalPolygon$new(circle(1, 0, 1.25))
# intersection
plgList <- plg1$intersection(plg2)
plg <- plgList[[1L]]
# plot
opar <- par(mar = c(0, 0, 0, 0))
plot(
NULL, xlim = c(-2.6, 2.6), ylim = c(-1.3, 1.3), asp = 1,
xlab = NA, ylab = NA, axes = FALSE
)
plg1$plot(lwd = 2, new = FALSE)
plg2$plot(lwd = 2, new = FALSE)
plg$plot(lwd = 3, col = "red", new = FALSE)
par(opar)
## ------------------------------------------------
## Method `cgalPolygon$isCWO`
## ------------------------------------------------
library(cgalPolygons)
ptg <- cgalPolygon$new(pentagram)
ptg$isCWO()
## ------------------------------------------------
## Method `cgalPolygon$isCCWO`
## ------------------------------------------------
library(cgalPolygons)
ptg <- cgalPolygon$new(pentagram)
ptg$isCCWO()
## ------------------------------------------------
## Method `cgalPolygon$isConvex`
## ------------------------------------------------
library(cgalPolygons)
ptg <- cgalPolygon$new(pentagram)
ptg$isConvex()
## ------------------------------------------------
## Method `cgalPolygon$isSimple`
## ------------------------------------------------
library(cgalPolygons)
ptg <- cgalPolygon$new(pentagram)
ptg$isSimple()
## ------------------------------------------------
## Method `cgalPolygon$minkowskiSum`
## ------------------------------------------------
library(cgalPolygons)
plg1 <- cgalPolygon$new(decagram)
plg2 <- cgalPolygon$new(star)
minko <- plg1$minkowskiSum(plg2)
minko$plot(lwd = 2, col = "yellowgreen")
## ------------------------------------------------
## Method `cgalPolygon$plot`
## ------------------------------------------------
library(cgalPolygons)
ptg <- cgalPolygon$new(pentagram)
ptg$plot(lwd = 3, col = "red")
## ------------------------------------------------
## Method `cgalPolygon$reverseOrientation`
## ------------------------------------------------
library(cgalPolygons)
ptg <- cgalPolygon$new(pentagram)
ptg$isCCWO()
ptg$reverseOrientation()
ptg$isCCWO()
## ------------------------------------------------
## Method `cgalPolygon$subtract`
## ------------------------------------------------
library(cgalPolygons)
# function creating a circle
circle <- function(x, y, r) {
t <- seq(0, 2, length.out = 100)[-1L]
t(c(x, y) + r * rbind(cospi(t), sinpi(t)))
}
# take two circles
plg1 <- cgalPolygon$new(circle(-1, 0, 1.25))
plg2 <- cgalPolygon$new(circle(1, 0, 1.25))
# difference
plgList <- plg1$subtract(plg2)
plg <- plgList[[1L]]
# plot
opar <- par(mar = c(0, 0, 0, 0))
plot(
NULL, xlim = c(-2.6, 2.6), ylim = c(-1.3, 1.3), asp = 1,
xlab = NA, ylab = NA, axes = FALSE
)
plg1$plot(lwd = 2, new = FALSE)
plg2$plot(lwd = 2, new = FALSE)
plg$plot(lwd = 3, col = "red", new = FALSE)
par(opar)
## ------------------------------------------------
## Method `cgalPolygon$symdiff`
## ------------------------------------------------
library(cgalPolygons)
# function creating a circle
circle <- function(x, y, r) {
t <- seq(0, 2, length.out = 100)[-1L]
t(c(x, y) + r * rbind(cospi(t), sinpi(t)))
}
# take two circles
plg1 <- cgalPolygon$new(circle(-1, 0, 1.25))
plg2 <- cgalPolygon$new(circle(1, 0, 1.25))
# symmetric difference
plgList <- plg1$symdiff(plg2)
plg <- plgList[[1L]]
# plot
opar <- par(mar = c(0, 0, 0, 0))
plot(
NULL, xlim = c(-2.6, 2.6), ylim = c(-1.3, 1.3), asp = 1,
xlab = NA, ylab = NA, axes = FALSE
)
plg1$plot(lwd = 2, new = FALSE)
plg2$plot(lwd = 2, new = FALSE)
plg$plot(list(lwd = 3, col = "red"), col = "white", new = FALSE)
par(opar)
## ------------------------------------------------
## Method `cgalPolygon$union`
## ------------------------------------------------
library(cgalPolygons)
# function creating a circle
circle <- function(x, y, r) {
t <- seq(0, 2, length.out = 100)[-1L]
t(c(x, y) + r * rbind(cospi(t), sinpi(t)))
}
# take two circles
plg1 <- cgalPolygon$new(circle(-1, 0, 1.25))
plg2 <- cgalPolygon$new(circle(1, 0, 1.25))
# union
plgList <- plg1$union(plg2)
plg <- plgList[[1L]]
# plot
opar <- par(mar = c(0, 0, 0, 0))
plot(
NULL, xlim = c(-2.6, 2.6), ylim = c(-1.3, 1.3), asp = 1,
xlab = NA, ylab = NA, axes = FALSE
)
plg1$plot(lwd = 2, new = FALSE)
plg2$plot(lwd = 2, new = FALSE)
plg$plot(lwd = 3, col = "red", new = FALSE)
par(opar)
## ------------------------------------------------
## Method `cgalPolygon$whereIs`
## ------------------------------------------------
library(cgalPolygons)
ptg <- cgalPolygon$new(pentagram)
pt1 <- c(0, 0) # inside
pt2 <- c(4, 0) # outside
ptg$whereIs(rbind(pt1, pt2))
cgalPolygons documentation built on May 31, 2023, 8:16 p.m.
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| cgalPolygon | R Documentation |
R6 class to represent a CGAL polygon
Description
R6 class to represent a CGAL polygon.
Methods
Public methods
Method new()
Creates a new cgalpolygon object.
Usage
cgalPolygon$new(vertices)
Arguments
verticesa numeric matrix with two columns
Returns
A cgalPolygon object.
Examples
library(cgalPolygons) ptg <- cgalPolygon$new(pentagram) ptg
Method print()
Print the cgalPolygon object.
Usage
cgalPolygon$print(...)
Arguments
...ignored
Returns
No value, just prints some information about the polygon.
Method area()
Signed area of the polygon.
Usage
cgalPolygon$area()
Returns
A number, the signed area of the polygon; it is positive if the polygon is counter-clockwise oriented, negative otherwise.
Examples
library(cgalPolygons) ptg <- cgalPolygon$new(pentagram) ptg$area() # should be 5 / sqrt(130 + 58*sqrt(5)) 5 / sqrt(130 + 58*sqrt(5))
Method boundingBox()
Bounding box of the polygon.
Usage
cgalPolygon$boundingBox()
Returns
A 2x2 matrix giving the lower corner of the bounding box in its first row and the upper corner in its second row.
Examples
library(cgalPolygons) ptg <- cgalPolygon$new(pentagram) plot(ptg$boundingBox(), asp = 1) polygon(pentagram)
Method convexParts()
Decomposition into convex parts. The polygon must be simple and counter-clockwise oriented.
Usage
cgalPolygon$convexParts(method = "optimal")
Arguments
methodthe method used:
"approx","greene", or"optimal"
Returns
A list of matrices; each matrix has two columns and represents a convex polygon.
Examples
library(cgalPolygons)
ptg <- cgalPolygon$new(pentagram)
cxparts <- ptg$convexParts()
ptg$plot(col = "yellow", lwd = 3)
invisible(
lapply(cxparts, function(cxpart) {
polygon(cxpart, lwd = 2)
})
)
Method getVertices()
Vertices of the polygon.
Usage
cgalPolygon$getVertices()
Returns
The vertices in a matrix with two columns.
Examples
library(cgalPolygons) ptg <- cgalPolygon$new(pentagram) ptg$getVertices()
Method intersection()
Intersection of the polygon with another polygon.
Usage
cgalPolygon$intersection(plg2)
Arguments
plg2a
cgalPolygonobject or acgalPolygonWithHolesobject
Returns
A list whose each element is either a cgalPolygon object
or a cgalPolygonWithHoles object.
Examples
library(cgalPolygons)
# function creating a circle
circle <- function(x, y, r) {
t <- seq(0, 2, length.out = 100)[-1L]
t(c(x, y) + r * rbind(cospi(t), sinpi(t)))
}
# take two circles
plg1 <- cgalPolygon$new(circle(-1, 0, 1.25))
plg2 <- cgalPolygon$new(circle(1, 0, 1.25))
# intersection
plgList <- plg1$intersection(plg2)
plg <- plgList[[1L]]
# plot
opar <- par(mar = c(0, 0, 0, 0))
plot(
NULL, xlim = c(-2.6, 2.6), ylim = c(-1.3, 1.3), asp = 1,
xlab = NA, ylab = NA, axes = FALSE
)
plg1$plot(lwd = 2, new = FALSE)
plg2$plot(lwd = 2, new = FALSE)
plg$plot(lwd = 3, col = "red", new = FALSE)
par(opar)
Method isCWO()
Checks whether the polygon is clockwise oriented.
Usage
cgalPolygon$isCWO()
Returns
A Boolean value.
Examples
library(cgalPolygons) ptg <- cgalPolygon$new(pentagram) ptg$isCWO()
Method isCCWO()
Checks whether the polygon is counter-clockwise oriented.
Usage
cgalPolygon$isCCWO()
Returns
A Boolean value.
Examples
library(cgalPolygons) ptg <- cgalPolygon$new(pentagram) ptg$isCCWO()
Method isConvex()
Checks whether the polygon is convex.
Usage
cgalPolygon$isConvex()
Returns
A Boolean value.
Examples
library(cgalPolygons) ptg <- cgalPolygon$new(pentagram) ptg$isConvex()
Method isSimple()
Checks whether the polygon is simple; that means its edges do not intersect (except two consecutive edges which intersect at their common vertex)
Usage
cgalPolygon$isSimple()
Returns
A Boolean value.
Examples
library(cgalPolygons) ptg <- cgalPolygon$new(pentagram) ptg$isSimple()
Method minkowskiSum()
Minkowski sum of the polygon and another polygon.
Usage
cgalPolygon$minkowskiSum(plg2)
Arguments
plg2a
cgalPolygonobject or acgalPolygonWithHolesobject, the polygon to add to the reference polygon
Returns
Either a cgalPolygonWithHoles object, or, in the case if
there is no hole in the Minkowski sum, a cgalPolygon object.
Examples
library(cgalPolygons) plg1 <- cgalPolygon$new(decagram) plg2 <- cgalPolygon$new(star) minko <- plg1$minkowskiSum(plg2) minko$plot(lwd = 2, col = "yellowgreen")
Method plot()
Plot the polygon.
Usage
cgalPolygon$plot(..., new = TRUE)
Arguments
...arguments passed to
polygonnewBoolean, whether to create a new plot
Returns
No returned value, called for side-effect.
Examples
library(cgalPolygons) ptg <- cgalPolygon$new(pentagram) ptg$plot(lwd = 3, col = "red")
Method reverseOrientation()
Reverse the orientation of the polygon.
Usage
cgalPolygon$reverseOrientation()
Returns
The cgalPolygon object, invisibly.
Examples
library(cgalPolygons) ptg <- cgalPolygon$new(pentagram) ptg$isCCWO() ptg$reverseOrientation() ptg$isCCWO()
Method subtract()
Difference between the polygon and another polygon.
Usage
cgalPolygon$subtract(plg2)
Arguments
plg2a
cgalPolygonobject or acgalPolygonWithHolesobject
Returns
A list whose each element is either a cgalPolygon object
or a cgalPolygonWithHoles object.
Examples
library(cgalPolygons)
# function creating a circle
circle <- function(x, y, r) {
t <- seq(0, 2, length.out = 100)[-1L]
t(c(x, y) + r * rbind(cospi(t), sinpi(t)))
}
# take two circles
plg1 <- cgalPolygon$new(circle(-1, 0, 1.25))
plg2 <- cgalPolygon$new(circle(1, 0, 1.25))
# difference
plgList <- plg1$subtract(plg2)
plg <- plgList[[1L]]
# plot
opar <- par(mar = c(0, 0, 0, 0))
plot(
NULL, xlim = c(-2.6, 2.6), ylim = c(-1.3, 1.3), asp = 1,
xlab = NA, ylab = NA, axes = FALSE
)
plg1$plot(lwd = 2, new = FALSE)
plg2$plot(lwd = 2, new = FALSE)
plg$plot(lwd = 3, col = "red", new = FALSE)
par(opar)
Method symdiff()
Symmetric difference of the polygon and another polygon.
Usage
cgalPolygon$symdiff(plg2)
Arguments
plg2a
cgalPolygonobject or acgalPolygonWithHolesobject
Returns
A list whose each element is either a cgalPolygon object
or a cgalPolygonWithHoles object.
Examples
library(cgalPolygons)
# function creating a circle
circle <- function(x, y, r) {
t <- seq(0, 2, length.out = 100)[-1L]
t(c(x, y) + r * rbind(cospi(t), sinpi(t)))
}
# take two circles
plg1 <- cgalPolygon$new(circle(-1, 0, 1.25))
plg2 <- cgalPolygon$new(circle(1, 0, 1.25))
# symmetric difference
plgList <- plg1$symdiff(plg2)
plg <- plgList[[1L]]
# plot
opar <- par(mar = c(0, 0, 0, 0))
plot(
NULL, xlim = c(-2.6, 2.6), ylim = c(-1.3, 1.3), asp = 1,
xlab = NA, ylab = NA, axes = FALSE
)
plg1$plot(lwd = 2, new = FALSE)
plg2$plot(lwd = 2, new = FALSE)
plg$plot(list(lwd = 3, col = "red"), col = "white", new = FALSE)
par(opar)
Method union()
Union of the polygon with another polygon.
Usage
cgalPolygon$union(plg2)
Arguments
plg2a
cgalPolygonobject or acgalPolygonWithHolesobject
Returns
A list whose each element is either a cgalPolygon object
or a cgalPolygonWithHoles object.
Examples
library(cgalPolygons)
# function creating a circle
circle <- function(x, y, r) {
t <- seq(0, 2, length.out = 100)[-1L]
t(c(x, y) + r * rbind(cospi(t), sinpi(t)))
}
# take two circles
plg1 <- cgalPolygon$new(circle(-1, 0, 1.25))
plg2 <- cgalPolygon$new(circle(1, 0, 1.25))
# union
plgList <- plg1$union(plg2)
plg <- plgList[[1L]]
# plot
opar <- par(mar = c(0, 0, 0, 0))
plot(
NULL, xlim = c(-2.6, 2.6), ylim = c(-1.3, 1.3), asp = 1,
xlab = NA, ylab = NA, axes = FALSE
)
plg1$plot(lwd = 2, new = FALSE)
plg2$plot(lwd = 2, new = FALSE)
plg$plot(lwd = 3, col = "red", new = FALSE)
par(opar)
Method whereIs()
Locate point(s) with respect to the polygon. The polygon must be simple.
Usage
cgalPolygon$whereIs(points)
Arguments
pointsa numeric matrix with two columns, or a numeric vector of length 2 (for a single point)
Returns
An integer vector with possible values -1, 1, or
0: value -1 for outside, 1 for inside, and
0 if the point is on the boundary of the polygon.
Examples
library(cgalPolygons) ptg <- cgalPolygon$new(pentagram) pt1 <- c(0, 0) # inside pt2 <- c(4, 0) # outside ptg$whereIs(rbind(pt1, pt2))
Examples
## ------------------------------------------------
## Method `cgalPolygon$new`
## ------------------------------------------------
library(cgalPolygons)
ptg <- cgalPolygon$new(pentagram)
ptg
## ------------------------------------------------
## Method `cgalPolygon$area`
## ------------------------------------------------
library(cgalPolygons)
ptg <- cgalPolygon$new(pentagram)
ptg$area() # should be 5 / sqrt(130 + 58*sqrt(5))
5 / sqrt(130 + 58*sqrt(5))
## ------------------------------------------------
## Method `cgalPolygon$boundingBox`
## ------------------------------------------------
library(cgalPolygons)
ptg <- cgalPolygon$new(pentagram)
plot(ptg$boundingBox(), asp = 1)
polygon(pentagram)
## ------------------------------------------------
## Method `cgalPolygon$convexParts`
## ------------------------------------------------
library(cgalPolygons)
ptg <- cgalPolygon$new(pentagram)
cxparts <- ptg$convexParts()
ptg$plot(col = "yellow", lwd = 3)
invisible(
lapply(cxparts, function(cxpart) {
polygon(cxpart, lwd = 2)
})
)
## ------------------------------------------------
## Method `cgalPolygon$getVertices`
## ------------------------------------------------
library(cgalPolygons)
ptg <- cgalPolygon$new(pentagram)
ptg$getVertices()
## ------------------------------------------------
## Method `cgalPolygon$intersection`
## ------------------------------------------------
library(cgalPolygons)
# function creating a circle
circle <- function(x, y, r) {
t <- seq(0, 2, length.out = 100)[-1L]
t(c(x, y) + r * rbind(cospi(t), sinpi(t)))
}
# take two circles
plg1 <- cgalPolygon$new(circle(-1, 0, 1.25))
plg2 <- cgalPolygon$new(circle(1, 0, 1.25))
# intersection
plgList <- plg1$intersection(plg2)
plg <- plgList[[1L]]
# plot
opar <- par(mar = c(0, 0, 0, 0))
plot(
NULL, xlim = c(-2.6, 2.6), ylim = c(-1.3, 1.3), asp = 1,
xlab = NA, ylab = NA, axes = FALSE
)
plg1$plot(lwd = 2, new = FALSE)
plg2$plot(lwd = 2, new = FALSE)
plg$plot(lwd = 3, col = "red", new = FALSE)
par(opar)
## ------------------------------------------------
## Method `cgalPolygon$isCWO`
## ------------------------------------------------
library(cgalPolygons)
ptg <- cgalPolygon$new(pentagram)
ptg$isCWO()
## ------------------------------------------------
## Method `cgalPolygon$isCCWO`
## ------------------------------------------------
library(cgalPolygons)
ptg <- cgalPolygon$new(pentagram)
ptg$isCCWO()
## ------------------------------------------------
## Method `cgalPolygon$isConvex`
## ------------------------------------------------
library(cgalPolygons)
ptg <- cgalPolygon$new(pentagram)
ptg$isConvex()
## ------------------------------------------------
## Method `cgalPolygon$isSimple`
## ------------------------------------------------
library(cgalPolygons)
ptg <- cgalPolygon$new(pentagram)
ptg$isSimple()
## ------------------------------------------------
## Method `cgalPolygon$minkowskiSum`
## ------------------------------------------------
library(cgalPolygons)
plg1 <- cgalPolygon$new(decagram)
plg2 <- cgalPolygon$new(star)
minko <- plg1$minkowskiSum(plg2)
minko$plot(lwd = 2, col = "yellowgreen")
## ------------------------------------------------
## Method `cgalPolygon$plot`
## ------------------------------------------------
library(cgalPolygons)
ptg <- cgalPolygon$new(pentagram)
ptg$plot(lwd = 3, col = "red")
## ------------------------------------------------
## Method `cgalPolygon$reverseOrientation`
## ------------------------------------------------
library(cgalPolygons)
ptg <- cgalPolygon$new(pentagram)
ptg$isCCWO()
ptg$reverseOrientation()
ptg$isCCWO()
## ------------------------------------------------
## Method `cgalPolygon$subtract`
## ------------------------------------------------
library(cgalPolygons)
# function creating a circle
circle <- function(x, y, r) {
t <- seq(0, 2, length.out = 100)[-1L]
t(c(x, y) + r * rbind(cospi(t), sinpi(t)))
}
# take two circles
plg1 <- cgalPolygon$new(circle(-1, 0, 1.25))
plg2 <- cgalPolygon$new(circle(1, 0, 1.25))
# difference
plgList <- plg1$subtract(plg2)
plg <- plgList[[1L]]
# plot
opar <- par(mar = c(0, 0, 0, 0))
plot(
NULL, xlim = c(-2.6, 2.6), ylim = c(-1.3, 1.3), asp = 1,
xlab = NA, ylab = NA, axes = FALSE
)
plg1$plot(lwd = 2, new = FALSE)
plg2$plot(lwd = 2, new = FALSE)
plg$plot(lwd = 3, col = "red", new = FALSE)
par(opar)
## ------------------------------------------------
## Method `cgalPolygon$symdiff`
## ------------------------------------------------
library(cgalPolygons)
# function creating a circle
circle <- function(x, y, r) {
t <- seq(0, 2, length.out = 100)[-1L]
t(c(x, y) + r * rbind(cospi(t), sinpi(t)))
}
# take two circles
plg1 <- cgalPolygon$new(circle(-1, 0, 1.25))
plg2 <- cgalPolygon$new(circle(1, 0, 1.25))
# symmetric difference
plgList <- plg1$symdiff(plg2)
plg <- plgList[[1L]]
# plot
opar <- par(mar = c(0, 0, 0, 0))
plot(
NULL, xlim = c(-2.6, 2.6), ylim = c(-1.3, 1.3), asp = 1,
xlab = NA, ylab = NA, axes = FALSE
)
plg1$plot(lwd = 2, new = FALSE)
plg2$plot(lwd = 2, new = FALSE)
plg$plot(list(lwd = 3, col = "red"), col = "white", new = FALSE)
par(opar)
## ------------------------------------------------
## Method `cgalPolygon$union`
## ------------------------------------------------
library(cgalPolygons)
# function creating a circle
circle <- function(x, y, r) {
t <- seq(0, 2, length.out = 100)[-1L]
t(c(x, y) + r * rbind(cospi(t), sinpi(t)))
}
# take two circles
plg1 <- cgalPolygon$new(circle(-1, 0, 1.25))
plg2 <- cgalPolygon$new(circle(1, 0, 1.25))
# union
plgList <- plg1$union(plg2)
plg <- plgList[[1L]]
# plot
opar <- par(mar = c(0, 0, 0, 0))
plot(
NULL, xlim = c(-2.6, 2.6), ylim = c(-1.3, 1.3), asp = 1,
xlab = NA, ylab = NA, axes = FALSE
)
plg1$plot(lwd = 2, new = FALSE)
plg2$plot(lwd = 2, new = FALSE)
plg$plot(lwd = 3, col = "red", new = FALSE)
par(opar)
## ------------------------------------------------
## Method `cgalPolygon$whereIs`
## ------------------------------------------------
library(cgalPolygons)
ptg <- cgalPolygon$new(pentagram)
pt1 <- c(0, 0) # inside
pt2 <- c(4, 0) # outside
ptg$whereIs(rbind(pt1, pt2))
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