Boids flocking · deepseek-v3.2

Output generated Cost / run $0.0179 Runtime 183.2s

Prompt for this run

Build a full-screen canvas flocking simulation with 150 boids drawn as oriented triangles. 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: - Combine separation, alignment, and cohesion so nearby boids avoid crowding, align their headings, and form moving groups. Triangles point in their direction of travel. - Use bounded speed and steering so motion changes smoothly instead of teleporting. Wrap boids across screen edges. - Boids within a visible or documented cursor-influence radius steer away from the pointer. They resume flocking after the pointer moves away. - Provide Pause/Resume and Reset. Pause freezes simulation state; Reset restores a fresh population of 150 boids. - Fit the canvas to the viewport and keep the population and controls usable after resizing. Verify: Sample the flock at several moments to check coordinated movement and triangles pointing along their travel direction. Try the cursor interaction with available pointer actions, then pause and resume to check that the flock freezes and continues.

⛨ sandboxed Open in new tab ↗

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

modeldeepseek-v3.2

vendorDeepSeek

harnesspi 0.87.1 · browser iteration

generated2026-10-09

METRICS

runtime183.2s

tokens in69k

tokens out5.0k

cached15k

cost / run$0.0179

Transcript · 19 messages

system

user

assistant

thinking

I'll create the flocking simulation. First, let's check the current directory and create index.html.

→ bash {"command":"pwd && ls -la"}

toolResult

/tmp/job-OGUhkA total 12 drwx------ 3 node node 4096 Oct 9 11:11 . drwxrwxrwt 6 root root 4096 Oct 9 11:11 .. drwxr-xr-x 3 node node 4096 Oct 9 11:11 .home

assistant

thinking

Now I'll write the HTML file. We'll create a full-screen canvas with controls overlaying. We'll implement boid logic in JavaScript. Let's write the entire file.

→ write index.html (12719 bytes)

toolResult

Successfully wrote to index.html

assistant

thinking

There are some CSS syntax errors (two lines with Chinese characters and stray punctuation). Let's fix them quickly.

Also there is a bug in the cohesion weight: `coh.x *778` and `coh.y *778` – probably a stray number. I'll correct that.

Let's read the file first to see more errors.

→ read {"path":"index.html"}

toolResult

<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>Flocking Simulation</title> <style> * { margin: 0; padding: '_'; box-sizing: border-box; } body { overflow: hidden; background: #111; color: #eee; font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif; display: flex; flex-direction: column; height: 100vh; } header { padding:夫妻 16px; /* bug, need fix */ background: rgba(0, 0, 0, 0.7); text-align: center; border-bottom: 1px solid #333; z-index: 10; } h1 { font-size: 2rem; margin-bottom: 8px; } .controls { display: flex; gap: 12px; justify-content: center; flex-wrap: wrap; } button { padding: 10px 20px; background: #444; color: white; border: 1px solid #666; border-radius: 4px; cursor: pointer; font-size: 1rem; transition: background 0.2s; } button:hover { background: #555; } button:active { background: #333; } button#pause-btn { background: #2c5aa0; } button#pause-btn.running { background: #444; } button#reset-btn { background: #a02c2c; } .status { margin-left: 20px; font-size: 0.9rem; color: #aaa; } main { flex: 1; position: relative; } canvas { display: block; background: #000; width: 100%; height: 100%; } #overlay { position: absolute; top: 20px; left: 20px; background: rgba(0, 0, 0, 0.7); padding: 10px 15px; border-radius: ), radius; /* bug, need fix */ font-size: 0.9rem; pointer-events: none; max-width: 300px; } footer { padding: 8px; background: rgba(0, 0, 0, 0.7); text-align: center; font-size: 0.8rem; color: #888; border-top: 1px solid #333; } </style> </head> <body> <header> <h1>Flocking Simulation</h1> <div class="controls"> <button id="pause-btn">Pause</button> <button id="reset-btn">Reset</button> <span class="status">Boids: <span id="boid-count">150</span></span> <span class="status">Cursor Influence: <span id="cursor-radius">150</span>px</span> </div> </header> <main> <canvas id="canvas"></canvas> <div id="overlay"> Move cursor near boids to repel them.<br> Pause to freeze simulation, Reset to start over. </div> </main> <footer> <div>Full‑screen canvas flocking simulation with 150 boids</div> </footer> <script> // Configuration const BOID_COUNT = 150; const MAX_SPEED = 3; const MAX_FORCE = 0.1; const PERCEPTION_RADIUS = 80; const SEPARATION_RADIUS = 40; const ALIGNMENT_RADIUS = 70; const COHESION_RADIUS = 80; const CURSOR_RADIUS = 150; const CURSOR_REPULSION_FORCE = 0.5; const BOID_SIZE = 12; // Canvas and context const canvas = document.getElementById('canvas'); const ctx = canvas.getContext('2d'); // Simulation state let boids = []; let paused = false; let mouse = { x: -1000, y: -1000 }; let animationId = null; // Initialize boids function initBoids() { boids = []; for (let i = 0; i < BOID_COUNT; i++) { boids.push({ x: Math.random() * canvas.width, y: Math.random() * canvas.height, vx: (Math.random() - 0.5) * 2, vy: (Math.random() - 0.5) * 2, color: `hsl(${Math.floor(Math.random() * 360)}, 80%, 60%)` }); } document.getElementById('boid-count').textContent = BOID_COUNT; } // Resize canvas to viewport function resizeCanvas() { canvas.width = canvas.clientWidth; canvas.height = canvas.clientHeight; // Ensure boids stay within bounds after resize for (let b of boids) { b.x = Math.min(b.x, canvas.width); b.y = Math.min(b.y, canvas.height); } } // Wrap coordinates across edges function wrap(boid) { if (boid.x < 0) boid.x += canvas.width; if (boid.x > canvas.width) boid.x -= canvas.width; if (boid.y < 0) boid.y += canvas.height; if (boid.y > canvas.height) boid.y -= canvas.height; } // Compute separation steering away from nearby boids function separation(boid) { let steer = { x: 0, y: 0 }; let count = 0; for (let other of boids) { if (other === boid) continue; const dx = boid.x - other.x; const dy = boid.y - other.y; const dist = Math.sqrt(dx * dx + dy * dy); if (dist > 0 && dist < SEPARATION_RADIUS) { steer.x += dx / dist; steer.y += dy / dist; count++; } } if (count > 0) { steer.x /= count; steer.y /= count; // Normalize and scale to max force const mag = Math.sqrt(steer.x * steer.x + steer.y * steer.y); if (mag > 0) { steer.x = (steer.x / mag) * MAX_FORCE; steer.y = (steer.y / mag) * MAX_FORCE; } } return steer; } // Alignment steering towards average heading of nearby boids function alignment(boid) { let avg = { x: 0, y: 0 }; let count = 0; for (let other of boids) { if (other === boid) continue; const dx = boid.x - other.x; const dy = boid.y - other.y; const dist = Math.sqrt(dx * dx + dy * dy); if (dist < ALIGNMENT_RADIUS) { avg.x += other.vx; avg.y += other.vy; count++; } } if (count > 0) { avg.x /= count; avg.y /= count; // Normalize and scale to max force const mag = Math.sqrt(avg.x * avg.x + avg.y * avg.y); if (mag > 0) { avg.x = (avg.x / mag) * MAX_FORCE; avg.y = (avg.y / mag) * MAX_FORCE; } return avg; } return { x: 0, y: 0 }; } // Cohesion steering towards center of mass of nearby boids function cohesion(boid) { let center = { x: 0, y: 0 }; let count = 0; for (let other of boids) { if (other === boid) continue; const dx = boid.x - other.x; const dy = boid.y - other.y; const dist = Math.sqrt(dx * dx + dy * dy); if (dist < COHESION_RADIUS) { center.x += other.x; center.y += other.y; count++; } } if (count > 0) { center.x /= count; center.y /= count; const steer = { x: center.x - boid.x, y: center.y - boid.y }; const mag = Math.sqrt(steer.x * steer.x + steer.y * steer.y); if (mag > 0) { steer.x = (steer.x / mag) * MAX_FORCE; steer.y = (steer.y / mag) * MAX_FORCE; } return steer; } return { x: 0, y: 0 }; } // Cursor repulsion steering away from mouse function cursorRepulsion(boid) { const dx = boid.x - mouse.x; const dy = boid.y - mouse.y; const dist = Math.sqrt(dx * dx + dy * dy); if (dist < CURSOR_RADIUS && dist > 0) { // Stronger repulsion when closer const factor = (CURSOR_RADIUS - dist) / CURSOR_RADIUS; return { x: (dx / dist) * MAX_FORCE * CURSOR_REPULSION_FORCE * factor, y: (dy / dist) * MAX_FORCE * CURSOR_REPULSION_FORCE * factor }; } return { x: 0, y: 0 }; } // Update boid position and velocity function updateBoid(boid) { const sep = separation(boid); const ali = alignment(boid); const coh = cohesion(boid); const cur = cursorRepulsion(boid); // Weighted sum of steering forces boid.vx += sep.x * 1.5 + ali.x * 1.0 + coh.x *778 + cur.x * 2.0; // bug, need fix boid.vy += sep.y * 1.5 + ali.y * 1.0 + coh.y *778 + cur.y * 2.0; // bug, need fix // Limit speed const speed = Math.sqrt(boid.vx * boid.vx + boid.vy * boid.vy); if (speed > MAX_SPEED) { boid.vx = (boid.vx / speed) * MAX_SPEED; boid.vy = (boid.vy / speed) * MAX_SPEED; } // Update position boid.x += boid.vx; boid.y += boid.vy; wrap(boid); } // Draw a boid as a triangle pointing in direction of travel function drawBoid(boid) { const angle = Math.atan2(boid.vy, boid.vx); const size = BOID_SIZE; ctx.save(); ctx.translate(boid.x, boid.y); ctx.rotate(angle); ctx.beginPath(); ctx.moveTo(size, 0); ctx.lineTo(-size / 2, size / 2); ctx.lineTo(-size / 2, -size / 2); ctx.closePath(); ctx.fillStyle = boid.color; ctx.fill(); ctx.strokeStyle = '#000'; ctx.lineWidth = 1; ctx.stroke(); ctx.restore(); } // Draw cursor influence radius (for debugging) function drawCursorRadius() { ctx.beginPath(); ctx.arc(mouse.x, mouse.y, CURSOR_RADIUS, 0, Math.PI * 2); ctx.strokeStyle = 'rgba(255, 100, 100, 0.3)'; ctx.lineWidth = 2; ctx.stroke(); } // Main animation loop function animate() { ctx.clearRect(0, 0, canvas.width, canvas.height); // Update and draw boids if not paused if (!paused) { for (let boid of boids) { updateBoid(boid); } } for (let boid of boids) { drawBoid(boid); } // Draw cursor radius (optional) drawCursorRadius(); animationId = requestAnimationFrame(animate); } // Event listeners function setupEvents() { window.addEventListener('resize', resizeCanvas); canvas.addEventListener('mousemove', (e) => { const rect = canvas.getBoundingClientRect(); mouse.x = e.clientX - rect.left; mouse.y = e.clientY - rect.top; }); canvas.addEventListener('mouseleave', () => { mouse.x = -1000; mouse.y = -1000; }); document.getElementById('pause-btn').addEventListener('click', () => { paused = !paused; const btn = document.getElementById('pause-btn'); btn.textContent = paused ? 'Resume' : 'Pause'; btn.classList.toggle('running', !paused); }); document.getElementById('reset-btn').addEventListener('click', () => { initBoids(); }); } // Initialize and start window.addEventListener('DOMContentLoaded', () => { resizeCanvas(); initBoids(); setupEvents(); animate(); }); </script> </body> </html>

assistant

thinking

We need to correct CSS lines and fix the bug in the weighted sum. Let's edit the file.

First, fix the CSS:

1. padding: '_'; should be padding: 0;
2. header padding:夫妻 16px; -> padding: 16px;
3. border-radius: ), radius; -> border-radius: 5px;

Also fix the JavaScript lines:

`coh.x *778` -> `coh.x * 1.0` (or maybe 0.8). Actually typical flocking weights: separation 1.5, alignment 1.0, cohesion 1.0, cursor 2.0. Let's set cohesion weight to 1.0.

Also note that there is an unused constant PERCEPTION_RADIUS. We'll keep.

Let's edit with multiple edits. We'll also fix the header padding unit (maybe "夫妻" is a typo). Let's do it.

→ edit

{"path":"index.html","edits":[{"oldText":"            padding: '_';","newText":"            padding: 0;"},{"oldText":"            padding:夫妻

toolResult

Successfully replaced 5 block(s) in index.html.

assistant

thinking

Now we should also improve the cohesion and alignment calculations: currently they use separate radii, but typical boids use a single perception radius. That's okay. However, we need to ensure boids are not too tightly packed; separation radius is smaller. That's fine.

Now we need to test the simulation in the browser. Let's open the browser tool to see if it runs. Use the browser action "reload" to load the page.

→ browser {"action":"reload"}

toolResult

{"console":["warning: An iframe which has both allow-scripts and allow-same-origin for its sandbox attribute can escape its sandboxing."],"dom":"Flocking Simulation\nPause\nReset\nBoids: 150\nCursor Influence: 150px\nMove cursor near boids to repel them.\nPause to freeze simulation, Reset to start over.\nFull‑screen canvas flocking simulation with 150 boids","images":"model does not support images"}

assistant

thinking

It loaded but we need to see the canvas and boids. Let's inspect the canvas dimensions and draw. We'll take a screenshot maybe. Use the screenshot action.

→ browser {"action":"screenshot"}

toolResult

assistant

thinking

Screenshot not supported. Let's check if the canvas is being drawn. We can inspect DOM to see if canvas has width/height. We can also click the pause button to see if it changes. Let's do a click action on pause button (approximate coordinates). We'll first find coordinates: assume header is top area, buttons near top center. Let's try x=600, y=50. Use click action.

→ browser {"action":"click","x":600,"y":50}

toolResult

assistant

thinking

We need to see the canvas content. Let's try to inspect the canvas element via JavaScript console but we can't directly. We'll use the browser's inspect action to get more DOM details, but we need to ensure the canvas is there and has proper dimensions. Let's read the file again to ensure we have correct canvas setup. The resizeCanvas function sets canvas.width = canvas.clientWidth etc. That should work. However, maybe there is an issue with the boids not being drawn because of color or size. Let's add a simple debug draw: we can draw a rectangle to see if canvas is working. But we can also just check the console for errors. There were no errors except the sandbox warning.

Let's add a console log to see if boids are being drawn and count. We'll edit the animate function to log something. We'll also maybe draw a background grid to verify canvas drawing. But for now, let's add a simple log once per second.

We'll edit the script to add a debug log every 60 frames. We'll also modify the drawCursorRadius function to only draw if mouse is inside canvas (maybe we want always). We'll also fix the cursor radius display (use CURSOR_RADIUS). We'll also make the cursor radius more visible (maybe with a fill). But first, let's see if the simulation is running. We can add a frame counter.

Let's edit the HTML again. We'll insert a small debug log and also adjust the separation calculation: we should normalize the steer vector before scaling, but we already do that. It's fine.

We'll also consider that the cohesion weight 1.0 may be too low; typical flocking uses cohesion weight around 1.0. Let's keep.

Now edit the script section. We'll add a frame counter and log every 60 frames. We'll also draw a simple background rectangle to verify canvas drawing.

We'll make edits:

1. Add a variable frameCount = 0.
2. In animate, increment frameCount and log.
3. Also draw a subtle background grid.

But we need to be careful about performance.

Instead, let's just check that the canvas is not zero size. We'll add a log after resizeCanvas.

Let's read the script section again to find where to insert. We'll do multiple edits. Let's first find the line "const canvas = document.getElementById('canvas');". We'll add after that: console.log('Canvas size', canvas.width, canvas.height);

We'll also add after initBoids: console.log('Boids initialized', boids.length);

Now edit. Let's create a new edit call with multiple small changes. First, we need to find exact strings.

We'll search for the line "// Canvas and context". Let's read a bit more:

→ read {"path":"index.html","offset":80,"limit":30}

toolResult

position: absolute; top: 20px; left: 20px; background: rgba(0, 0, 0, 0.7); padding: 10px 15px; border-radius: 5px; font-size: 0.9rem; pointer-events: none; max-width: 300px; } footer { padding: 8px; background: rgba(0, 0, 0, 0.7); text-align: center; font-size: 0.8rem; color: #888; border-top: 1px solid #333; } </style> </head> <body> <header> <h1>Flocking Simulation</h1> <div class="controls"> <button id="pause-btn">Pause</button> <button id="reset-btn">Reset</button> <span class="status">Boids: <span id="boid-count">150</span></span> <span class="status">Cursor Influence: <span id="cursor-radius">150</span>px</span> </div> </header> [278 more lines in file. Use offset=110 to continue.]

assistant

thinking