Intro to Animation

Opener

Write two functions:

• rotator: image -> image that turns the image 10 degrees.

• middle-placer: image -> image that places the given image in the center of a yellow circle of radius 200.

Animation Code

(define starter (rectangle 50 200 "solid" "purple"))
(define delay-time 3)
(big-bang starter
          (on-tick rotator delay-time)
          (on-draw middle-placer))

Animation Vocabulary

• model: the part that changes

• on-tick: model -> model

  Moves to next time.

• on-draw: model -> image

  Shows the result. Draw things that do not move here.

Paper Exercise I

• A shape is shown on a yellow circle of radius 200.

• The shape grows 25% larger every tick, but the circle does not.

1. Write a tick handler.

2. Write the big-bang.

Paper Exercise II

• A shape starts in the center of a circle.

• The shape moves to the right 10 pixels every tick.

Write the tick handler

Class work

Exercises 6.4.2 and 6.4.3 (pdf page 106)

Bonus: 6.4.4

Homework

Read Section 6.3 (beginner mistakes)

Animation more vocab

• on-key: model key -> model

• on-mouse: model number(x) number(y) event -> model

You found the code!