(snapshot CAM-ID FILENAME [FORMAT [XSIZE [YSIZE]]])Save a snapshot of CAM-ID in the FILENAME (a string). The
FORMAT argument is optional; it may be "ppmscreen" (the default),
"ps", "ppm", "sgi" (on SGI machines), "ppmosmesa" (if built with
libOSMesa) or "ppmosglx". A "ppmscreen" snapshot is created by reading
the image directly from the given window; the window is popped above
other windows and redrawn first, then its contents are written as a PPM
format image. A "ppmosmesa" snapshot is drawn by Mesa’s software
renderer into a memory buffer in RAM. A "ppmosglx" snapshot is rendered
into a GLX Pixmap buffer, which is also off-screen but may or may not
reside in video RAM. Rendering may or may not be accelerated. The
problem with on-screen snapshots is that the window must be mapped and
not obscured by other windows. So on-screen snapshots will not work in
the background, or when a screen saver is active. With "ps", dumps a
Postscript picture representing the view from that window;
hidden-surface removal might be incorrect. With "ppm", dumps a
PPM-format image produced by geomview’s internal software renderer; this
may be of arbitrary size. If the FILENAME argument begins with
"|", it’s interpreted as a /bin/sh command to which the PPM or PS
data should be piped. Optional XSIZE and YSIZE values are
relevant only for "ppm" formats, and render to a window of that size (or
scaled to that size, with aspect fixed, if only XSIZE is given)