1. Putting Objects in Motion
Using Method Calls
Copyright © Curt Hill

2. Overview Each object is prepared to do certain things
A method call uses one of these behaviors
Since Alice is mostly about 3D animations these are mostly about moving in some way
This presentation uses existing methods
We later see creating our own
Copyright © Curt Hill

3. Objects Again Each actor, such as a fish, is an object
Any object may have methods that cause it to do something useful, such as move in some direction
An object may actually be composed of objects
A hand has actions different than the whole body
Yet moving the whole body must also move the hand
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4. Screen Shot
The next two screens show a program in the process of creation
The objects to be manipulated are listed
The first shows the fish as selected
It is surrounded by its bounding box
Bottom left shows the methods that can be used
After that the sub-object of the fish are shown
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7. Programming
The programming of this system is causing the actors to move properly
Errors are called bugs
A bug in Alice results in a scene that does not unfold as intended
Causing an object to move is to execute the move method
This is done using drag and drop
Copyright © Curt Hill

8. Getting things to move Click on the object to select it
Drag the action from the details pane to the method pane
Fill in the needed parameters if there are any
Test it by hitting the play button
The order of the actions in the method pane determine how they are executed
Copyright © Curt Hill

9. Adding an Action
What follows are four screens that show how to add action to a scene
Select the object to be acted on
Drag the move method to the Method Pane
Choose Forward and the distance
Finally what the program looks like when this instruction has been added
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14. Concurrency
Concurrency is two or more things happening at the same time
It is a fancy Computer Science term that we usually do not teach until students are quite experienced
Except in Alice!
Here we have a Do Together that does concurrency
Makes it look easy
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15. Do Together
The Do Together tab is at the bottom of the Method pane along with:
Do In Order
If Else
Loop
While
etc
All of these are containers for other statements
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16. Containers A container is a statement that contains other statements
When it is drug onto the pane it contains nothing
You then drag statements into it
These can be existing statements or new ones
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17. Do in Order Another container
This forces actions to be performed in order
Use Do Together to do things simultaneously and Do in Order to do things sequentially
Any of the containers may be in another
A Do in Order could be inside a Do Together
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18. Demo Now lets get things moving
Instead of a 3D post card we get a 3D animation
Use methods of move, roll, turn
Use Do Together and Do In Order
Copyright © Curt Hill