1. Functions

2. Functions Methods that return a Value
Number
Boolean (True/False)
Object
Other (Sound, Video, etc.)
Does not change the current state of the world
Does not move / change objects

3. What Functions Do Check a current condition (run-time)
Get information about objects
Where they are
Size
Ask questions about the state of the world
As it is now  With program running

4. Built In Functions Proximity Size Spatial Relationship Point of View
Relation to other objects
Size
Spatial Relationship
Point of View
Proximity – where the object is
Distance to
Distance to right/left/above/below/behind
Size:
Height
Width
Depth
Smaller Than/Larger Than
Spatial Relationship
To the left of
To the right of
above / below
in front of / behind
Point of View:
Point of View
Position

5. Where to Use – Calling the Function
Anywhere that requires the type of information returned from the function
Number
Object
Boolean
Example: Bopper.move (how far)
Bopper.move (distanceTo(mole))

6. Create Your Own Function
Exercise 6-1 #2
Create a new world with a car or truck. Write a program to make the 4 wheels of the car realistically turn forward as the car moves forward.
Why a function???
Roll and move forward at the same time doesn’t look realistic.
When cars move the tires do not rotate at the same rate as the car is moving forward
Rotation must be based on the size of the tires
(distance / (3.14 * diameter))

7. Create Your Own Function
Like Creating a Method
Select Object in Object Tree
Select Functions from
Details Window
Create New Function

8. Create Your Own Function
Name
Type  Return Type
Must have a Return Type
Number
Boolean
Object Other

9. Coding Function Code Function Cannot Delete the Return Statement
All functions return some Information

10. Call the Function
Function Call