Double pendulum · gpt-5.6-terra
Output generated Cost / run $0.0462 Runtime 52.6s
Prompt for this run
Build a planar double-pendulum simulation on a canvas with a colorful fading trail at the lower bob. Use HTML, CSS, and JavaScript as needed. Write it to `index.html` in the current working directory using your file tools. Inline your own CSS and JavaScript. Do not use external assets, CDNs, or network requests. No third-party libraries are provided. Required behavior: - Model two point masses connected by massless rigid rods under gravity, without damping or external driving. Use the coupled equations of motion rather than independent sine-wave animations. - Use equal masses and rod lengths, gravity of 9.81 in consistent simulation units, initial angles of 120 and -10 degrees measured from downward vertical, and zero initial angular velocities. - Draw a fixed pivot, both rods and bobs, and a bounded fading trail of the lower bob. Keep both rod lengths constant and the pendulum visible. - Provide Pause/Resume and Reset. Reset restores the stated initial conditions and clears the trail. - Use a numerically stable integration scheme and time step so ordinary playback does not explode or freeze. Verify: Sample the pendulum at several moments to inspect coupled motion, connected rods, and the lower-bob trail. Pause and resume to check the motion control, then reset and confirm that the starting pose and cleared trail return.
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
METRICS
Transcript · 21 messages
Build a planar double-pendulum simulation on a canvas with a colorful fading trail at the lower bob. Use HTML, CSS, and JavaScript as needed. Write it to `index.html` in the current working directory using your file tools. Inline your own CSS and JavaScript. Do not use external assets, CDNs, or network requests. No third-party libraries are provided. Required behavior: - Model two point masses connected by massless rigid rods under gravity, without damping or external driving. Use the coupled equations of motion rather than independent sine-wave animations. - Use equal masses and rod lengths, gravity of 9.81 in consistent simulation units, initial angles of 120 and -10 degrees measured from downward vertical, and zero initial angular velocities. - Draw a fixed pivot, both rods and bobs, and a bounded fading trail of the lower bob. Keep both rod lengths constant and the pendulum visible. - Provide Pause/Resume and Reset. Reset restores the stated initial conditions and clears the trail. - Use a numerically stable integration scheme and time step so ordinary playback does not explode or freeze. Verify: Sample the pendulum at several moments to inspect coupled motion, connected rods, and the lower-bob trail. Pause and resume to check the motion control, then reset and confirm that the starting pose and cleared trail return.
thinking
index.html (6918 bytes)Successfully wrote to index.html
thinking
{"action":"reload","x":0,"y":0,"toX":0,"toY":0,"text":"","delta":0}Frame 1, +0ms
[Browser image supplied to model]
{"console":["warning: An iframe which has both allow-scripts and allow-same-origin for its sandbox attribute can escape its sandboxing."],"dom":"Double Pendulum\nRUNNING\nm₁ = m₂ • L₁ = L₂\ng = 9.81 | no damping\nSimulation time: 0.33 s\nPause\nReset","images":"attached"}
thinking
**Trying to capture browser moments** I think I need to sample several moments from the browser, maybe by taking screenshots. I’ll have to wait to see if the browser action is unsupported. I should capture the screenshots after observing the necessary time, and during that time, I might need to click pause and then resume or reset while inspecting. It seems like I’m figuring out the best method to document what I’m seeing.
{"action":"screenshot","x":0,"y":0,"toX":0,"toY":0,"text":"","delta":0}Frame 1, +0ms
[Browser image supplied to model]
{"console":["warning: An iframe which has both allow-scripts and allow-same-origin for its sandbox attribute can escape its sandboxing."],"dom":"Double Pendulum\nRUNNING\nm₁ = m₂ • L₁ = L₂\ng = 9.81 | no damping\nSimulation time: 3.68 s\nPause\nReset","images":"attached"}
thinking
{"action":"click","x":938,"y":743,"toX":0,"toY":0,"text":"","delta":0}Frame 1, +0ms
[Browser image supplied to model]
{"console":["warning: An iframe which has both allow-scripts and allow-same-origin for its sandbox attribute can escape its sandboxing."],"dom":"Double Pendulum\nPAUSED\nm₁ = m₂ • L₁ = L₂\ng = 9.81 | no damping\nSimulation time: 6.28 s\nResume\nReset","images":"attached"}
thinking
{"action":"screenshot","x":0,"y":0,"toX":0,"toY":0,"text":"","delta":0}Frame 1, +0ms
[Browser image supplied to model]
{"console":["warning: An iframe which has both allow-scripts and allow-same-origin for its sandbox attribute can escape its sandboxing."],"dom":"Double Pendulum\nPAUSED\nm₁ = m₂ • L₁ = L₂\ng = 9.81 | no damping\nSimulation time: 6.28 s\nResume\nReset","images":"attached"}
thinking
{"action":"click","x":931,"y":743,"toX":0,"toY":0,"text":"","delta":0}Frame 1, +0ms
[Browser image supplied to model]
{"console":["warning: An iframe which has both allow-scripts and allow-same-origin for its sandbox attribute can escape its sandboxing."],"dom":"Double Pendulum\nRUNNING\nm₁ = m₂ • L₁ = L₂\ng = 9.81 | no damping\nSimulation time: 6.38 s\nPause\nReset","images":"attached"}
{"action":"click","x":1025,"y":743,"toX":0,"toY":0,"text":"","delta":0}Frame 1, +0ms
[Browser image supplied to model]
{"console":["warning: An iframe which has both allow-scripts and allow-same-origin for its sandbox attribute can escape its sandboxing."],"dom":"Double Pendulum\nRUNNING\nm₁ = m₂ • L₁ = L₂\ng = 9.81 | no damping\nSimulation time: 0.08 s\nPause\nReset","images":"attached"}
thinking
**Considering pose reset** I need to reset the pose exactly at the time when the evidence is at 0.08. So, to make this work smoothly, I should pause the process right before resetting it to zero. First, I'll confirm the starting pose and make sure it's cleared. Then, I'll click pause and reset while it's still paused. It sounds simple enough, but I want to ensure I get it right!
{"action":"click","x":936,"y":743,"toX":0,"toY":0,"text":"","delta":0}Frame 1, +0ms
[Browser image supplied to model]
{"console":["warning: An iframe which has both allow-scripts and allow-same-origin for its sandbox attribute can escape its sandboxing."],"dom":"Double Pendulum\nPAUSED\nm₁ = m₂ • L₁ = L₂\ng = 9.81 | no damping\nSimulation time: 4.53 s\nResume\nReset","images":"attached"}
thinking
{"action":"click","x":1021,"y":743,"toX":0,"toY":0,"text":"","delta":0}Frame 1, +0ms
[Browser image supplied to model]
{"console":["warning: An iframe which has both allow-scripts and allow-same-origin for its sandbox attribute can escape its sandboxing."],"dom":"Double Pendulum\nPAUSED\nm₁ = m₂ • L₁ = L₂\ng = 9.81 | no damping\nSimulation time: 0.00 s\nResume\nReset","images":"attached"}
Implemented the self-contained double-pendulum simulation in **`index.html`**. Verified in the browser: - Coupled double-pendulum motion at several simulation times, with fixed-length connected rods. - Colorful bounded/fading lower-bob trail. - Pause holds both pose and simulation time; Resume restarts motion. - Reset restores the specified 120° / −10° starting pose, zeroes the timer, and clears the trail. - No application console errors (only the browser sandbox warning).