Interaction

NodeBox is designed to output PDF documents or images, when you want to do all sorts of moving and interactive things you're probably better off with a tool like Processing.

However, if you do want to experiment with interactivity in NodeBox, there's some built-in support that might be of help to you. This assumes you already know how to make an animation in NodeBox.

Interacting with the mouse

In a NodeBox animation, there are three predefined variables that store the current position of the mouse cursor and the state of the mouse button:

• MOUSEX: the horizontal location of the mouse cursor
• MOUSEY: the vertical location of the mouse cursor
• mousedown: is True when the mouse button is pressed, False otherwise

You would typically use the mousedown variable in an if-statement:

if mousedown:
     # do stuff when the mouse is pressed
else:
     # do stuff when the mouse isn't pressed

Interacting with the keyboard

Three predefined variables store the keys a user is pressing during a NodeBox animation:

• key: the last key pressed
• keycode: the integer keycode of the last key pressed
• keydown: is True when a key is being pressed, False otherwise

The key and keycode variables are updated as long as any key is being pressed.

KEY_UP, KEY_DOWN_ KEY_LEFT, KEY_RIGHT, KEY_BACKSPACE contain the keycodes for the arrow keys and the backspace key.

Example

A fun example is this little sketch application. Simply run the code and draw some stuff on the canvas!

Play movie

size(400 ,400)
speed(30)
 
def setup():
    
    global path, d
    path = []
 
def draw():
    
    global path
 
    nofill()
    stroke(0)
    autoclosepath(False)
    
    if mousedown:
        pt = Point(MOUSEX, MOUSEY)
        path.append(pt)
        
    if len(path) > 0:
        first = True
        for pt in path:
            if first:
                beginpath(pt.x, pt.y)
                first = False
            else:
                lineto(pt.x, pt.y)
        endpath()