VC is basically a browser for VC syntax compliant XML files.
The browsing of a VC scene file is launched through a command line that defines the configuration file and the scene file(s).
During the browsing of a VC scene file, most user interactions are defined through scripts made of commands with a trigger event, an action, and one or more targets (see Chapter 6). There are however a few basic scene-independent interactions that are implemented in VC and do not require any specific command.
In the current version of VC, scene graphs cannot be graphically edited, they must be edited with an XML editor.
The arguments of the command line for launching the browsing of a VC scene are:
an optional configuration file,
one or more VC scene graph description files.
If no configuration file is provided, the default configuration file name is VirChor.conf. The configuration file must have a .conf extension, and the scene description file must have an .xml extension.
The syntax of VC command line is:
VirChor [configuration.conf] (3Dscene.xml)+
For instance, the following command browses the VC scene file Bercy-3Dscene.xml and uses the configuration file Bercy.conf:
VirChor Bercy.conf Bercy-3Dscene.xml
Once a VC scene graph is loaded, VC is in the browsing mode in which the user interacts with the scene according to predefined commands and to scene specific commands included into scripts. We now examine these two modes in turn.
The display is made of one or more window layouts defined in the windows. element of the configuration file. There is only one selected window at a time: the window in which the cursor is located for OpenGL rendering. Interactions only apply to the selected window and are used to change the current viewpoint of the user associated with the window, or to move the user inside the coordinate system of its current viewpoint.
Most user interactions are defined through scripts and commands in the VC scene graph description file (see Chapter 7). There are however a few predefined commands that are implemented in VC and that can be used with any scene file.
switches between full-screen and custom-size rendering,
associates the current user of the selected window with the next viewpoint,
associates the current user of the selected window with the previous viewpoint,
increases the update speed,
decreases the update speed,
increases the height of the current user of the selected window above its current viewpoint,
decreases the height the current user of the selected window above its current viewpoint,
turns the current user of the selected window towards left,
turns the current user of the selected window towards right,
increases the pitch of the current user of the selected window,
decreases the pitch of the current user of the selected window,
switches on and off frame-rate display,
outputs the current scene graph to a file named VC-out.xml,
prints a snapshot of the current frame according to the value of the shots attribute tiff_rendering_file element in the configuration file,
terminates the current rendering.
The mouse can be used to control the displacements of the current user of the selected window with respect to its current viewpoint. Shift clicking on the left button makes the user move backward.
In addition, the right and left movements of the mouse control the horizontal motion directions, and the up and down movements of the mouse control the pitch of the user (towards the sky or towards the ground). If the user is bent down the user moves downwards in addition to moving forwards when left clicking on the mouse. If the user is tilted up the user moves upwards in addition to moving forwards when left clicking on the mouse.