CS320n Visual Programming

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CS320n Visual Programming

• Problem Solving Case Study
• (Slides 6-3)

Thanks to Wanda Dann, Steve Cooper, and Susan
Rodger for slide ideas.
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What We Will Do Today

• Look at a complicated problem
• Discuss different ways of solving it
• Learn some techniques in Alice
• Practice Writing methods and functions

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Problem to Solve

• Create a scene with 3 animals standing in a row
• resize each of them from 0.5 to 3 times its
  original size
• Find the animal that is tallest and spin it once
  to the right and once to the left
• Sort the animals by their height smallest on the
  cameras left, tallest on the cameras right
• Display message In order any time the animals
  are sorted

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Objects in the World

• Animals Penguin, Joey, White Rabbit
• careful to pick animals whose center point is at
  their feet
• challenging if center point is higher
• position animals 1 meter apart (use move to and
  move methods in set up)
• Need some way to track position
• fixed objects (balls)
• 3D text In Order! in scene but invisible

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Initial Scene
tennis ball is position 1, toy ball is position
2, volleyball is position 3 Use these as fixed
points of reference
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Storyboard

• check if animals are sorted
• resize animals
• check if animals are sorted
• make tallest spin
• sort animals
• display in order (assuming sorted)

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world.my first method
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make Tallest Animal Spin Around

• find out which is tallest
• spin it around right, then spin it around left
• create a function to determine which of the three
  things is tallest

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tallest Of Three

• How do we do this?
• Its not so bad for 3 but if there were more it
  would become too complicated

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check If Sorted By Height

• How do we check if items are sorted by increasing
  height?
• Check if object in position 1 is shorter than
  object in position 2 and if object in position 2
  is shorter than object in position 3?
• How do we know which animal is in which position?

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which Object Is Closest To
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sort Animals By Height

• How?
• More than one way?
• Again, if we get more than 3 becomes very
  complicated, very quickly

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One Way

• determine which thing is in which position
• determine which thing is tallest
• if tallest is not in position 3, swap tallest
  with thing in position 3
• then check if the thing in position 2 is taller
  than the thing in position 1
• if not then swap those 2
• animals next to each other started out 1.5 meters
  apart
• or could use distance to the left / right function

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(No Transcript)