rgl.setMouseCallbacks: User callbacks on mouse events

Description

Set and get user callbacks on mouse events.

Usage

rgl.setMouseCallbacks(button, begin = NULL, update = NULL, end = NULL)
rgl.getMouseCallbacks(button)
rgl.setWheelCallback(rotate)
rgl.getWheelCallback()

Arguments

button

Which button?

begin

Called when mouse down event occurs

update

Called when mouse moves

end

Called when mouse is released

rotate

Called when mouse wheel is rotated

Value

The set functions are called for the side effect of setting the mouse event handlers.
The rgl.getMouseCallbacks function returns a list containing the callback functions or NULL if no user callback is set. The rgl.getWheelCallback returns the callback function or NULL.

Details

The set functions set event handlers on mouse events that occur within the current rgl window. The begin and update events should be functions taking two arguments; these will be the mouse coordinates when the event occurs. The end event handler takes no arguments. The rotate event takes a single argument, which will be equal to 1 if the user pushes the wheel away by one click, and 2 if the user pulls the wheel by one click.

Alternatively, the handlers may be set to NULL, the default value, in which case no action will occur.

If a subscene has multiple listeners, the user action will still only be called for the subscene that received the mouse event. It should consult par3d("listeners") if it makes sense to take action on the whole group of subscenes.

The get function retrieves the callbacks that are currently set.

Examples

Run this code

## Not quite right --- this doesn't play well with rescaling

 pan3d <- function(button) {
   start <- list()
   
   begin <- function(x, y) {
       start$userMatrix <<- par3d("userMatrix")
       start$viewport <<- par3d("viewport")
       start$scale <<- par3d("scale")
       start$projection <<- rgl.projection()
       start$pos <<- rgl.window2user( x/start$viewport[3], 1 - y/start$viewport[4], 0.5, 
                                      projection = start$projection)
   }
   
   update <- function(x, y) {
        xlat <- (rgl.window2user( x/start$viewport[3], 1 - y/start$viewport[4], 0.5,
                                 projection = start$projection) - start$pos)*start$scale
        mouseMatrix <- translationMatrix(xlat[1], xlat[2], xlat[3])
        par3d(userMatrix = start$userMatrix %*% t(mouseMatrix) )
   }
   rgl.setMouseCallbacks(button, begin, update)
   cat("Callbacks set on button", button, "of rgl device", rgl.cur(), "")
 }
 pan3d(3)