# inashape3d

##### Test of the inside of an \(\alpha\)-shape

This function checks whether points are inside an \(\alpha\)-shape.

##### Usage

`inashape3d(as3d, indexAlpha = 1, points)`

##### Arguments

- as3d
An object of class

`"ashape3d"`

that represents the \(\alpha\)-shape of a given sample of points in the three-dimensional space, see`ashape3d`

.- indexAlpha
A single value or vector with the indexes of

`as3d$alpha`

that should be used for the computation, see Details.- points
A 3-column matrix with the coordinates of the input points.

##### Details

The function `inashape3d`

checks whether each point in `points`

is
inside the \(\alpha\)-shape for each value of \(\alpha\) in
`as3d$alpha[indexAlpha]`

.

If `indexAlpha="all"`

or `indexAlpha="ALL"`

then the function
checks whether each point in `points`

is inside the \(\alpha\)-shape
for all values of \(\alpha\) in `as3d$alpha`

.

##### Value

If `indexAlpha`

is a single value then the function returns a
vector of boolean of length the number of input points. The element at
position `i`

is `TRUE`

if the point in `points[i,]`

is inside
the \(\alpha\)-shape.

Otherwise `inashape3d`

returns a list of vectors of boolean values
(each object in the list as described above).

##### See Also

##### Examples

```
# NOT RUN {
T1 <- rtorus(2000, 0.5, 2)
T2 <- rtorus(2000, 0.5, 2, ct = c(2, 0, 0), rotx = pi/2)
x <- rbind(T1, T2)
ashape3d.obj <- ashape3d(x, alpha = 0.4)
# Random sample of points in a plane
points <- matrix(c(5*runif(10000) - 2.5, rep(0.01, 5000)), nc = 3)
in3d <- inashape3d(ashape3d.obj, points = points)
plot(ashape3d.obj, transparency = 0.2)
colors <- ifelse(in3d, "blue", "green")
rgl.points(points, col = colors)
# }
```

*Documentation reproduced from package alphashape3d, version 1.3, License: GPL-2*