gpclib (version 1.5-6)

# new-generics: Generics/Methods for polygon objects

## Description

Some generic functions and methods for polygon objects

## 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

## 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.

## 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.

`"gpc.poly"` class documentation.
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