# new-generics

##### Generics/Methods for polygon objects

Some generic functions and methods for polygon objects

- Keywords
- methods

##### Usage

```
append.poly(x, y)
area.poly(object, …)
get.pts(object)
get.bbox(x)
scale.poly(x, …)
tristrip(x)
triangulate(x)
```

##### Arguments

- x,object
A polygon object

- y
A polygon object

- …
Other arguments passed to methods

##### Details

The result of `tristrip(x)`

is a list of two-column matrices. Each
matrix is a tristrip, i.e. the rows are vertices of triangles, with
each overlapping triple of rows corresponding to a separate triangle.

The result of `triangulate(x)`

is a single two-column matrix. The
rows are vertices of triangles, taken in non-overlapping triples.

##### Methods

- append.poly
`signature(x = "gpc.poly", y = "gpc.poly")`

: Combine all contours of two`"gpc.poly"`

objects and return the combined polygon as a`"gpc.poly"`

object.- area.poly
`signature(object = "gpc.poly")`

: Compute and return the sum of the areas of all contours in a`"gpc.poly"`

object.- scale.poly
`signature(x = "gpc.poly")`

: Scale (divide) the x and y coordinates of a`"gpc.poly"`

object by the amount`xscale`

and`yscale`

, respectively. Return a scaled`"gpc.poly"`

object.- get.pts
`signature(object = "gpc.poly")`

: Return the list of x and y coordinates of the vertices of a`"gpc.poly"`

object.- get.bbox
`signature(x = "gpc.poly")`

: Return the bounding box for a`"gpc.poly"`

object.- tristrip
`signature(x = "gpc.poly")`

: Return a tristrip list for a`"gpc.poly"`

object.- triangulate
`signature(x = "gpc.poly")`

: Return a matrix of vertices of a triangulation of a`"gpc.poly"`

object.

##### See Also

`"gpc.poly"`

class documentation.

##### Examples

```
# NOT RUN {
holepoly <- read.polyfile(system.file("poly-ex/hole-poly.txt", package =
"gpclib"), nohole = FALSE)
area.poly(holepoly)
stopifnot(area.poly(holepoly) == 8)
# }
```

*Documentation reproduced from package gpclib, version 1.5-6, License: file LICENSE*