The rendering process works in two stages. The first step writes an input file for the image processing program selected in the Output Formats browser, and the second (optionally) starts the rendering process. The file is given the name entered in the Output Filename field; a default name is given when a new format is selected, so it is best to hold off entering the filename until after the file format is selected. Another way to select the filename is available by pressing the List... button, which opens up a file browser.
Pressing the Go button writes the data file. After that, the Render Command is executed. The default command should start the appropriate rendering program if it is available.
The fastest of the currently supported programs is Raster3D.
The rendering
command for it has been set up to call the SGI program ipaste
when the RGB output file is finished. VMD will wait for the
rendering to finish, which causes VMD to freeze, so you may want to
run the job in the background. This can be done by enclosing the
existing text with ()'s and putting an & at the end. For
example, the way to make the Raster3D render command run in the
background is:
(render < %s -sgi %s.rgb; ipaste %s.rgb)&