Animations Summary

This is a summary, not an introduction. It has a digest of all of the information you will want later.

Essentials

These essentials are on page 100 (PDF page 111) or page 138 (PDF page 149). There is a detailed checklist on page 105 (PDF page 116). Use it! You should memorize them.

• model: What the computer remembers.

• draw-handler: model -> image: Draw the model on the screen; adds non-moving parts to the image. (on-draw)

• tick-handler: model -> model: Update the model as time passes. (on-tick)

• key-handler: model key -> model: Update the model when a key is hit. (on-key)

• mouse-handler: model x y event -> model: Update the model when the mouse is moved or clicked. The inputs x and y are numbers, the event is a string. (on-mouse)

Design Process

When designing every function, these are the steps you should follow:

1. Signature
2. Purpose
3. Example
4. Function — write it
5. Test — check-expect

Reference: page 70 (PDF page 81) has a longer version of the same list.

F.A.Q.

• Q: Why do you write “model” when the model is just an image?

  A: Next chapter our models will be numbers, and soon after that our models will be sentences. If you memorize “model” as the type, you don’t need to memorize a new signature every chapter.