TNT Tool Time — Entry #7 — Python Processing

Xmas Lights

Stars that twinkle like Christmas lights — and a tree waiting to be decorated.
Pure Python Processing. Copy it, run it, then ask AI to build a Christmas tree and constrain the lights to it. Holiday spirit, powered by code.

🎄 Tool Time Entry #7 — Python Processing

Twinkling Stars That Look Like Christmas Lights

This Python Processing sketch was created as group work in TNT’s Foundations class. It draws 400 twinkling colored lights (styled as stars) against a deep purple night sky. Each “star” cycles independently through the full color spectrum while its brightness pulses smoothly — the effect looks remarkably like a string of Christmas lights.

We are showcasing this as-is, then using AI to transform it: draw a polygonal Christmas tree on the canvas and constrain all the lights to fall only on the tree. Copy the code, paste it into Python Processing, and watch it run. Then start the holiday adventure.

Note on randomSeed(100): The star positions are recalculated every frame, but randomSeed(100) resets the random number sequence each time — so the positions never change. The animation is the color and brightness changing, not the positions. Remove the seed and watch what happens.

By Foundations Class Group Work • Python Processing • 60 lines Original source — exactly as written, including the commented setup() stub

Your Turn — Get Into the Holiday Spirit

Hit Copy above, paste into Python Processing (File → New, then paste), and run it. The lights twinkle immediately. Then follow the stages below.

💻 Stage 1 — Run It, Understand It

Watch the animation. Notice:

Colors cycle independently — hue_family = map(sin(frameCount*.05 + 5*ndx), -1, 1, 0, 360) gives each star a different phase in the color cycle.
Brightness pulses — glow = map(sin(frameCount*.1 + ndx), -1, 1, 0, 100) makes each star fade in and out at a slightly different rate.
Positions never move — randomSeed(100) resets the sequence every frame. Remove it and see what happens!

🌲 Stage 2 — Draw a Christmas Tree

Ask your AI assistant:

You are a patient Python Processing teacher. I have a twinkling stars sketch.
Add a function draw_tree() that draws a simple Christmas tree as a green
filled triangle using beginShape(), vertex(), and endShape(CLOSE).
Center the tree horizontally on the 600-wide canvas, with the tip at y=50
and the base at y=360. Add a brown rectangle for the trunk.
Call draw_tree() from draw(), after the background and before draw_stars().

📌 Stage 3 — Constrain Lights to the Tree

Right now stars appear everywhere. After drawing the tree, modify draw_stars() so lights only appear inside the triangle. Ask AI to add a point_in_triangle() helper and wrap each circle in an if check:

def point_in_triangle(px, py, ax, ay, bx, by, cx, cy):
    # Returns True if (px, py) is inside the triangle (ax,ay),(bx,by),(cx,cy)
    def sign(p1x, p1y, p2x, p2y, p3x, p3y):
        return (p1x - p3x) * (p2y - p3y) - (p2x - p3x) * (p1y - p3y)
    d1 = sign(px, py, ax, ay, bx, by)
    d2 = sign(px, py, bx, by, cx, cy)
    d3 = sign(px, py, cx, cy, ax, ay)
    has_neg = (d1 < 0) or (d2 < 0) or (d3 < 0)
    has_pos = (d1 > 0) or (d2 > 0) or (d3 > 0)
    return not (has_neg and has_pos)

⭐ Stage 4 — Decorate!

Once the lights are on the tree, keep going:

⭐ Star on top 🌲 Tiered tree (3 triangles) ⚪ Garland line 🌕 Moon or falling snow 💡 Change blink speed 💥 Bigger / fewer lights 🟥 Only red & green lights 🎁 Presents under the tree

🔧 C.R.A.F.T. your ask. Context: “I have a Python Processing sketch with twinkling stars [describe what you’ve built so far]”; Role: “Act as a patient Python Processing teacher”; Action: name the stage (add tree / constrain lights / decorate); Form: “Show the complete updated sketch with comments”; Tight: “Keep the twinkling behavior; only add/change what’s needed.”
Full C.R.A.F.T. breakdown at Tool Time Home ↓