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Chapter 2

Creating Your First Animation

(An Introduction to Programming)

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Creating an Animation

Given the description of a • story, • game, • simulation

create an Alice animation

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Creating an Animation

• Recommended approach• Read the scenario, • Design an animation using storyboards, • Implement your design• Test your design• If the animation is not correct repeat this process

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Example • Read the “First Encounter” scenario:

“After traveling through space, …• Design

• From the scenario, determine the problem to be solved: • What is the story to be told?• What objects are required?• What actions are needed?

• Use the storyboard technique to outline a solution• Implementation

• Create an initial scene• Translate the storyboard actions into code

• Test• Determine if the implementation meets the requirements of the

scenario

See pages 20+

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Creating Your First Animation• First Encounter scenario:

After traveling through space, a robot-manned craft has just made a landing on a moon. The robot is on the moon and has set up a camera so earthbound scientists in Houston can view this historic event. The camera view shows the robot, the lunar Lander and some nearby rock formations. Suddenly an alien peeks out from behind a rock, surprising the robot. The robot looks around, spots the alien, and walks over to take a closer look. The alien is frightened and hides behind the rocks.

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Storyboards

• Two forms you might use:• Visual

• hand-sketched • screen captures

• Textual • Algorithm• Pseudocode

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Storyboards• The text’s textual storyboard

• The above outlines an algorithm – a set of instructions to follow to accomplish a task

• The above is also referred to as pseudocode – it is very close to the program code generated by Alice

Do the following steps in order alien moves up alien says "Slithy toves?" robot's head turns around robot turns to look at alien Do together robot moves toward the alien robot legs walk alien moves down

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Your First Program• Implementing the design

• Select a world• Choose your objects• Create an initial scene• Edit World.my first method

• create instructions using objects, methods, …

See class demoNote how the animation

is developed piece by piece - incrementally

•Do in order•Do together•If/Else•Loop•While

•For all in order•For all together•Wait •Print •// comments

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Your First ProgramTesting your implementation

• Play your world• Observe the behaviour• Is the behaviour what you expected?• If yes … then you are done• Otherwise … you have a bug and you need to

• Determine what needs to change• Is the scenario correct? • Is your design correct?• Is your code correct?

• Make the changes and repeat this whole process again

See class demo

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Point of View• An object’s Point of View comprises its position and

orientation. • Position tells us where the object is in the world. • Orientation tells us the direction an object is facing.

• An object’s position is given by 3 values: location in the world’s LR axis, location in the world’s FB axis, location in the world’s UD axis. See the pointOfView.position property values.

• An object’s orientation is given by 3 values: yaw, pitch, roll. Yaw is the objects rotation about the UD axis. Pitch is the object’s rotation about the LR axis. Roll is the object’s rotation about the FB axis.

• See The PointOfView property for objects

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Orientation of objects

• Each object has its own coordinate system that provides its own sense of direction

• If Bob is asked to turn left ¼ revolution, Bob’s sense of direction turns with him

forward

forward

Bob

Note here that Bob rotated on his up-down axis. An object’s yaw is how much the object is rotated along this up-down axis since its original position.

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Orientation of objects

• Bob had just turned…

• Now if we ask Bob to move forward, Bob advances along the forward-backward axis

forward

forward

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Orientation of objects

• Bob had moved forward…

• Now if we ask Bob to turn forward, Bob rotates on the left-right axis

forward

forward

right

Note here that Bob rotated on his left-right axis. An object’s pitch is how much the object is rotated along this left-right axis since its original position.

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Orientation of objects

• Consider Bob back at …

• Now if we ask Bob to roll left, Bob rotates on the forward-backward axis

Note here that Bob rotated on his forward-backward axis. An object’s roll is how much the object is rotated along this forward-backward axis since its original position.

forward

forward

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Orientation of objects

• Each object has its own coordinate system that provides its own sense of direction

• If Dave and Peter are asked to move forward, they go in opposite directions

• You reset an object’s coordinate system by using orient to to give both the same sense of direction

• Dave orient to Peter

forwardforward

forwardforward

Dave Peter

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Arguments

• Duration: the default length of time for an action is one second – this can be modified

• Style: the smoothness of an action is controlled using one of the values begin gently, begin abruptly, end gently, end abruptly

• As seen by: the sense of direction (orientation) for an action is by default determined by the object that is acting, but this can be changed by specifying a different object to use for direction