A scene from scratch

Challenge 19 of 20

A whole little world in five lines. The order matters more than usual here: the ground has to be painted after the background and before the sun, or it simply covers it up.

Write the five lines.

Your code JavaScript

Write the five lines.

Console print() output

0 / 55 frames · 400×400

Target

Yours

Yours over Target — ghosted shapes are in the target but missing from yours

Results

Press Run to check your code

Penalties: none this run

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Lesson Animate It Yourself

You already know all of this.

Every line this topic asks for is one you have read many times: a step (x = x + speed;), a limit (x = limit(x, 40, 360);), a shape (circle(x, y, 80);) or a colour (shapeColour(CYAN);). The comment above each empty line says what it needs to do. Nothing new arrives.

Order is not decoration.

Inside everyFrame the lines run top to bottom, every frame. The background has to come first or it paints over everything else. A colour has to be chosen before the shape that uses it. A limit has to come after the step that made the number too big, not before it.

The background is what wipes the last frame.

Leave it out and the frame you drew before is still there, so a moving shape smears across the window instead of moving. Challenge 7 shows you exactly that — run it before you fix it.

Read the error panel.

A typed line can be wrong in ways a number never was: a missing bracket, a misspelled name, a capital letter in the wrong place. The panel under the canvases names the line and says what went wrong. It is quicker than staring at the code.

One topic still to come, and it takes the scaffolding away as well: an empty editor, and every line — everyFrame, the background, the variables, the sums — written by you. There is no readout line down there either, so the picture is all you get.