Where we are on the rocket

▶ ◀

You're on Stage 3 of 10. Welcome to The Body of the rocket. 💪

What are colours, really?

A screen is made of tiny dots called pixels. Every pixel can glow in three lights at once: Red, Green, and Blue. Mix the three lights at different brightness levels and you get every colour you've ever seen on a screen.

In pygame, a colour is just three numbers: (red, green, blue). Each number is from 0 (off) to 255 (full brightness). So:

• (0, 0, 0) — all lights off → black
• (255, 255, 255) — all lights on full → white
• (255, 0, 0) — only red → pure red
• (0, 255, 0) — only green → pure green
• (255, 215, 0) — red and a lot of green → gold/yellow
• (0, 0, 50) — a tiny bit of blue → deep space-blue

🎨 Try opening the Google colour picker and copy the "RGB" values it shows. You can use those numbers directly in pygame.

So why give them names?

Imagine writing a whole game and seeing this everywhere:

pygame.draw.rect(screen, (255, 215, 0), player)
pygame.draw.rect(screen, (255, 215, 0), bullet)
screen.fill((0, 0, 50))

What does (255, 215, 0) mean again? You'd forget in 10 minutes.

Instead, we store each colour in a variable with a clear name:

YELLOW = (255, 215, 0)
SPACE  = (0, 0, 50)

pygame.draw.rect(screen, YELLOW, player)
pygame.draw.rect(screen, YELLOW, bullet)
screen.fill(SPACE)

Same code, but readable. Anyone who looks at it (you, next month, or your friend) instantly knows what's going on. Programmers do this for almost everything — it's one of the most important habits you'll learn.

✨ Style tip: colours that never change are written in ALL_CAPS. That's how other coders know "don't change this — it's a constant."

The recipe

1. After your imports and screen setup, add a section called # COLOURS.
2. Pick a name (in ALL_CAPS) and a (R, G, B) value for each colour you'll use.
3. Save each pair into a variable: RED = (255, 0, 0).
4. Anywhere you'd type the numbers, type the name instead.
5. Run the game — if a colour needs tweaking, change ONE place and it updates everywhere.

The code so far

# Stage 1 — Imports
import pygame

# Stage 2 — Setup the Screen
pygame.init()
WIDTH = 800
HEIGHT = 600
screen = pygame.display.set_mode((WIDTH, HEIGHT))
pygame.display.set_caption("Galaxy Defender")
clock = pygame.time.Clock()

# Stage 3 — Colours (R, G, B) ✨
BLACK  = (0, 0, 0)
WHITE  = (255, 255, 255)
RED    = (255, 0, 0)
GREEN  = (0, 255, 0)
YELLOW = (255, 215, 0)
SPACE  = (0, 0, 50)

# Tiny test loop — paint the screen SPACE blue and a YELLOW square
running = True
while running:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False
    screen.fill(SPACE)
    pygame.draw.rect(screen, YELLOW, (350, 250, 100, 100))
    pygame.display.flip()
    clock.tick(60)

pygame.quit()

Run this and you'll see a deep space-blue window with a glowing yellow square in the middle. Notice how the code reads like a sentence: "fill the screen SPACE, draw a YELLOW rectangle." That's the whole point of Stage 3. 🎉

🎮 Want to play with more code? Scroll down to the Lesson 3 Code Library (5 colour games). Copy any program, paste it into the editor below, and press the green ▶ Run button.

Handouts for this lesson

Print these, keep them open in another tab, or download them to your computer.

📚 Lesson 3 Code Library — 5 brand-new pygame mini-games all about colour: Palette Test Card, Rainbow Stripes, Traffic Light, RGB Mixer, Random Sky.

📄 Lesson 3 Code Library (5 colour games) 📄 Lesson 2 Code Library 📄 Lesson 1 Code Library

🗺️ The big-picture handouts — keep these by your side for the whole course.

📄 Rocket Ladder 📄 Pixel Cheat Sheet 📄 Code Recipe 🖼️ 6 Parts of a Turtle Program

🤖 Want to try your own idea? Ask an AI like Claude or ChatGPT something like "Write me a short pygame program that draws a rainbow", then paste the code into the Trinket above and click Run.