Returns the angle, in radians, from point 1 to point 2.
The co-ordinates of point 1 are provided by x1 and y1, whilst the co-ordinates for point 2 are provided by x2 and y2.
* Fills a 'pacman' shape based on the location
* of the cursor.
* The segment size is based on the angle from
* the centre of the screen to the mouse.
fill( :green )
// the point
x = getScreenWidth()/2
y = getScreenHeight()/2
mx = getControls().getMouseX()
my = getControls().getMouseY()
angle = getAngle( x, y, mx, my )
setColor( :white )
fillSegment( x, y, 150, 0, angle, true )