par3dinterp {rgl} | R Documentation

## Interpolator for par3d parameters

### Description

Returns a function which interpolates `par3d` parameter values, suitable for use in animations.

### Usage

    par3dinterp(times = NULL, userMatrix, scale, zoom, FOV,
                method = c("spline", "linear"),
                extrapolate = c("oscillate", "cycle", "constant", "natural"),
                dev = rgl.cur(), subscene = currentSubscene3d(dev))

### Arguments

`times` | Times at which values are recorded or a list; see below
`userMatrix` | Values of `par3d("userMatrix")`
`scale` | Values of `par3d("scale")`
`zoom` | Values of `par3d("zoom")`
`FOV` | Values of `par3d("FOV")`
`method` | Method of interpolation
`extrapolate` | How to extrapolate outside the time range
`dev` | Which rgl device to use
`subscene` | Which subscene to use

### Details

This function is intended to be used in constructing animations. It produces a function that returns a list suitable to pass to `par3d`, to set the viewpoint at a given point in time.

All of the parameters are optional. Only those `par3d` parameters that are specified will be returned.

The input values other than `times` may each be specified as lists, giving the parameter value settings at a fixed time, or as matrices or arrays. If not lists, the following formats should be used: `userMatrix` can be a `4 x 4 x n` array, or a `4 x 4n` matrix; `scale` should be an `n x 3` matrix; `zoom` and `FOV` should be length `n` vectors.

An alternative form of input is to put all of the above arguments into a list (i.e. a list of lists, or a list of arrays/matrices/vectors), and pass it as the first argument. This is the most convenient way to use this function with the `tkrgl` function `par3dsave`.

Interpolation is by cubic spline or linear interpolation in an appropriate coordinate-wise fashion. Extrapolation may oscillate (repeat the sequence forward, backward, forward, etc.), cycle (repeat it forward), be constant (no repetition outside the specified time range), or be natural (linear on an appropriate scale). In the case of cycling, the first and last specified values should be equal, or the last one will be dropped. Natural extrapolation is only supported with spline interpolation.

### Value

A function is returned. The function takes one argument, and returns a list of `par3d` settings interpolated to that time.

### Author(s)

Duncan Murdoch

### See Also

`play3d` to play the animation.

### Examples

    f <- par3dinterp( zoom = c(1, 2, 3, 1) )
    f(0)
    f(1)
    f(0.5)
    ## Not run:
    play3d(f)

    ## End(Not run)

[Package rgl version 0.95.1441 Index]