Bouncing balls in a heptagon · qwen3.8-2.4t-a95b
Show 20 numbered balls (1 to 20) dropping from the center of a heptagon that spins 360 degrees every 5 seconds. The balls are affected by gravity and friction, collide with each other, and bounce realistically off the rotating walls; show each ball's spin via the rotation of its number. Implement all collision detection yourself.
transcript · 6 messages
Show 20 numbered balls (1 to 20) dropping from the center of a heptagon that spins 360 degrees every 5 seconds. The balls are affected by gravity and friction, collide with each other, and bounce realistically off the rotating walls; show each ball's spin via the rotation of its number. Implement all collision detection yourself.
thinking
Physics: heptagon rotating with 360°/5s = angular velocity ω = 2π/5 rad/s. Balls are generated one by one from the center (falling). Gravity, friction, ball-to-ball collision, ball-to-wall collision accounting for wall velocity due to rotation (tangential velocity of the wall's contact point), bounce with coefficient of restitution, and friction applies spin to the balls (displayed by rotation of the drawn numbers). Implementing circle vs line segment (polygon edge) collision. For each edge, find the closest point from the ball's center to the segment; if dist < r, push it out and apply impulse in the normal direction, including the wall velocity at the contact point: v_wall = ω × r_vec (for rotation about the center). Friction: apply tangential impulse proportional to the relative tangential velocity; also apply spin to the ball (angular velocity) — friction torque couples the surface velocity and spin. Write the code.
/tmp/ws/index.html (14348 bytes)Successfully wrote 14348 bytes to /tmp/ws/index.html
thinking
Let me quickly verify whether the physics is working (a headless browser probably isn't available, but a basic sanity check via a simple JS syntax check with node is possible).
Let me verify the JS is syntactically valid:
{"command":"cd /tmp/ws && node -e \"\nconst html = require('fs').readFileSync('index.html','utf8');\nconst m = html.match(/<script>([\\s\\S]JS syntax OK, script length: 13497 -rw-r--r--. 1 node node 14378 Aug 13 01:26 index.html
thinking
Complete. Let me summarize concisely.
Done — `/tmp/ws/index.html` is a fully self-contained single-file app (no external resources). Just open it in a browser. **What it does:** - **Heptagon**: 7-sided polygon spinning at exactly 2π/5 rad/s (360° every 5s), with a highlighted top vertex so rotation is easy to see. - **20 numbered balls** drop one by one (every 0.28s) from the center, each with a distinct color. - **Physics** (all hand-rolled, no libraries): - Gravity, air drag, and damping - **Ball↔ball collisions**: circle-circle overlap detection, positional correction weighted by mass, restitution impulse, plus Coulomb-capped tangential friction impulses that transfer angular velocity between balls - **Ball↔wall collisions**: closest-point-on-segment test per edge; wall contact-point velocity is computed from the heptagon's rotation (`v = ω × r`), so the spinning walls realistically "scoop" and fling the balls; friction against the moving wall also imparts spin - Spin is integrated as real angular velocity (with inertia `I = 0.4·m·r²`) and rendered as the **rotation of each ball's number** (plus a small notch dot so rotation is visible even on symmetric digits) - **Stability**: 4 physics sub-steps per frame, 3 collision iterations per step, clamped `dt`, and a safety ring to keep balls inside. The JS passed a syntax check via Node; no network requests or external files are used.
TAKE IT TO CODE
A single self-contained HTML file — copy it and open in any browser, or reuse the prompt with your own pi-agent run.
RUN
EVALUATION
Heptagon rotates, 20 numbered balls drop, collide, and settle at bottom with visible spin; no distinct input response but simulation runs well.
Vision grade · anthropic/claude-sonnet-5
MEASUREMENTS
Raw readings from the capture, not a verdict — the grade above is the only judgement. Percentages are how much of the screen changed; the measure under-reports sparse motion on a dark background.