# Intro to Animation
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# 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.
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# Animation Code
```racket
(define starter (rectangle 50 200 "solid" "purple"))
(define delay-time 3)
(big-bang starter
(on-tick rotator delay-time)
(on-draw middle-placer))
```
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# 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.
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# 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.
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# 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
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# Class work
Exercises 6.4.2 and 6.4.3 (pdf page 106)
Bonus: 6.4.4
# Homework
Read Section 6.3 (beginner mistakes)
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# Animation more vocab
* on-key: model key -> model
* on-mouse: model number(x) number(y) event -> model
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You found [the code!](animation-day1.rkt)