07. Tutorial 7

In this tutorial, we learn how to connect dynamically perception (here, detection of a ball) to action (here smiling) using the targeting keyword.

This program set our robot (represented by an emoticon) to smile every time a ball gets close.

program:

	# would likely be a computer vision related node in real applications
	virtual_balls_detection

	# display the robot (just an emoticon with a facial expression)
	display_robot

	# display the ball (just the color spelled, e.g. 'BLUE')
	targeting ball: ball_display

	# the robot smiles every time a ball is close by
	targeting ball: smile, while distance<4, priority of 2

	# facial expression of the robot when not smiling
	# (if 'distance<4' is false for all balls, then the
	# 'smile' nodes of higher priority 2 do not activate,
	# leaving the 'face' resource free and accessible to 'stay_put')
	stay_put, priority of 1

You may try to update the priority of stay_put to 3: the robot will never smile.

stay_put is the lower priority facial expression (priority of 1), i.e. the default one when nothing else is going on. When a ball gets close ('while distance<4') then smile activates, and because it is with a priority above stay_put (priority of 1), it overrides it (the "face" resource is attributed to it).

Python code for "distance":

# Distance is an evaluation based on the position property.
# Similarly to the ball_display node, it needs to be used
# along the "targeting" keyword.
# The engine will pass the correct scheme_id parameter automatically

def distance(scheme_id=None):

    position = playful.memory.get_property_value("position",scheme_id=scheme_id)
    if not position :
        return float("+inf")
    return abs(Playful_tutorial_robot.position-position)

To relate to a real application. In script used in the video : https://www.youtube.com/watch?v=dEw4XptasWc there is :

targeting blue_cup: smile, priority of 2
targeting hand: look_surprized, priority of 1

if you look carefully, you may see this is what the head of the robot does (among other things)