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The paper: where every painting starts

Every painting needs something to paint on. In the paint studio that's the paper: a square sheet you fill with color before anything else goes on top.

The big idea

The paper is a square, 400 steps wide and 400 steps tall. paper() fills all of it with one color, so it goes first.

See it in code

1Start simple

paper() takes one color name and fills the whole sheet. Everything you paint after it lands on top:

python
paper("light salmon")
circle(x=290, y=110, size=90, color="gold")
A sheet of color, and a sun on it:
A sheet of light salmon paper filled edge to edge, with one gold circle painted near the top right.

Two commands, two layers. The paper is the bottom layer, and the sun sits on it.

2A step further

The paper ends at 400 across and 400 down. A shape can hang off the edge, and only the part on the paper shows:

python
paper("light sky blue")
rect(x=200, y=260, width=400, height=80, color="turquoise")
rect(x=200, y=350, width=400, height=100, color="sandy brown")
circle(x=0, y=400, size=260, color="tan")
A dune that's mostly off the paper:
A beach in three bands of sky, sea, and sand, with a tan sand dune curving up from the bottom-left corner where most of a large circle hangs off the paper.

That dune is a circle centered on the corner, at x=0, y=400. Three quarters of it is off the paper, and the leftover quarter makes a hill.

3In the paint studio

sky() fills the paper as well, but with a blend. Give it a top color and a bottom color and it fades one into the other:

python
sky(top_color="indigo", bottom_color="dark orange")
circle(x=200, y=250, size=110, color="gold")
rect(x=200, y=330, width=400, height=140, color="midnight blue")
A sunset in one line:
A sunset sky blending from deep purple at the top to orange at the bottom, with a gold sun sinking into a dark blue sea.

sky() and paper() do the same job: they cover everything. Use one of them at the very start, then build your scene on top.

The same idea, everywhere

A game works the same way. Its window is bigger, 640 by 480, and it repaints the background on every frame before drawing the pieces.

Try it yourself

Swap the two colors in sky() and run it. Is it sunrise or sunset now? Then move the sun's y to 150 and decide where the sea should start.

The common mistake

Calling paper() in the middle of a painting. It covers everything painted before it, so your shapes vanish. The paper goes first, once.

What it unlocks

Now learn to place things on the paper with x and y, fill it with shapes, and stack them in the right order with layers.

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