`ageSetter.Rd`

Many RGL shapes contain lists of vertices with various
attributes (available via `rgl.attrib`

). This function
modifies the data for those attributes in a WebGL scene.

```
ageSetter(births, ages,
colors = NULL, alpha = NULL, radii = NULL,
vertices = NULL, normals = NULL, origins = NULL,
texcoords = NULL,
objids, prefixes = "", digits = 7,
param = seq(floor(min(births)), ceiling(max(births))))
```

births | Numeric vector with one value per vertex, used to determine the “age” of the vertex when displaying it. |
---|---|

ages | A non-decreasing sequence of “ages”. |

colors, alpha, radii, vertices, normals, origins, texcoords | Attributes of the vertices. Non- |

objids, prefixes | The object ids and scene prefixes to modify. These are recycled to the same length. |

digits | How many digits to output in the generated Javascript code. |

param | Default values to be used by a slider control calling the generated function. |

The vertex attributes are specified as follows:

- colors
A vector of colors in a format suitable for input to

`col2rgb`

- alpha
A numeric vector of alpha values between 0 and 1.

- radii
A numeric vector of sphere radii.

- vertices
A 3-column matrix of vertex coordinates.

- normals
A 3-column matrix of vertex normals.

- origins
A 2-column matrix of origins for text or sprites.

- texcoords
A 2-column matrix of texture coordinates.

All attributes must have the same number of entries (rows for the matrices)
as the `ages`

vector. The `births`

vector must have the
same number of entries as the number of vertices in the object.

Not all objects contain all attributes listed here; if one is
chosen that is not a property of the corresponding object, a
Javascript `alert()`

will be generated.

A character vector of class `c("ageSetter", "propertySetter")`

containing Javascript
code defining a function suitable for use in a `propertySlider`

.

The function takes a single argument, `time`

, and uses it to compute the
“age” of vertex `i`

as `time - births[i]`

.
Those are then used with the `ages`

argument to linearly interpolate settings of the specified attributes.
Extrapolation is constant. Repeated values in `ages`

can be used
to obtain discontinuities in the settings.

Duncan Murdoch

`propertySlider`

; more detailed control is available in
`vertexSetter`

.