Return true if the left mouse button has been released on the current frame, and otherwise returns false.
A click differs from being down by only being recorded for one frame, rather then permanently, whilst the button is pressed.
A block can be attached onto 'isLeftClick', which will only be executed if the left mouse button is being click on this frame. This will be passed in the x and y location of the mouse.
/* Player shoots at the mouse location,
* when the mouse is clicked. */
getControls().isLeftClick() do |x, y|
player.shootAt( x, y )