R: Extract pixel information from window

rgl.pixels {rgl} | R Documentation

## Extract pixel information from window

### Description

This function extracts single components of the pixel information from the topmost window.

### Usage

    rgl.pixels(component = c("red", "green", "blue"),
            viewport = par3d("viewport"), top = TRUE)

### Arguments

`component` | Which component(s)?
`viewport` | Lower left corner and size of desired region.
`top` | Whether to bring window to top before reading.

### Details

The possible components are `"red"`, `"green"`, `"blue"`, `"alpha"`, `"depth"`, and `"luminance"` (the sum of the three colors). All are scaled from 0 to 1.

Note that the luminance is kept below 1 by truncating the sum; this is the definition used for the `GL_LUMINANCE` component in OpenGL.

### Value

A vector, matrix or array containing the desired components. If one component is requested, a vector or matrix will be returned depending on the size of block requested (length 1 dimensions are dropped); if more, an array, whose last dimension is the list of components.

### Author(s)

Duncan Murdoch

### See Also

`rgl.snapshot` to write a copy to a file, `demo("stereo")` for functions that make use of this to draw a random dot stereogram and an anaglyph.

### Examples

    example(surface3d)
    depth <- rgl.pixels(component = "depth")
    if (length(depth) && is.matrix(depth)) # Protect against empty or single pixel windows
        contour(depth)

[Package rgl version 0.99.9 Index]