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Fluid simulation · muse-spark-1.3

Output generated Cost / run $0.1736 Runtime 120.6s

Prompt for this run

Build an interactive 2D fluid-and-dye simulation on a full-screen canvas. 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: - Maintain a velocity field and a colored dye field. Advect dye through the moving fluid so it forms persistent swirling flow; a collection of independent fading particles is not sufficient. - Dragging injects dye and momentum in the drag direction. Momentum and dye remain visible after the pointer is released and gradually dissipate. Approximate fluid behavior is acceptable; choose the numerical method and Canvas 2D or WebGL implementation. - Seed the initial scene with a small amount of colored dye and motion so the simulation is visible on load. - Provide a color selector, Pause/Resume, and Clear. Clear removes dye and resets velocity; the next drag can start a new flow. - Bound simulation resolution and work per frame so controls remain responsive at a 1200 by 800 viewport. Verify: Drag through the canvas and sample the flow after release. Check that dye follows the drag, continues swirling, and responds to a second drag in another direction. Use Clear, then drag again to check that a fresh flow can start.

⛨ 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

modelmuse-spark-1.3
vendorMeta
harnesspi 0.87.1 · browser iteration
generated2026-10-09

METRICS

runtime120.6s
tokens in248k
tokens out10k
cached165k
cost / run$0.1736
Transcript · 34 messages
system

user

Build an interactive 2D fluid-and-dye simulation on a full-screen canvas. 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: - Maintain a velocity field and a colored dye field. Advect dye through the moving fluid so it forms persistent swirling flow; a collection of independent fading particles is not sufficient. - Dragging injects dye and momentum in the drag direction. Momentum and dye remain visible after the pointer is released and gradually dissipate. Approximate fluid behavior is acceptable; choose the numerical method and Canvas 2D or WebGL implementation. - Seed the initial scene with a small amount of colored dye and motion so the simulation is visible on load. - Provide a color selector, Pause/Resume, and Clear. Clear removes dye and resets velocity; the next drag can start a new flow. - Bound simulation resolution and work per frame so controls remain responsive at a 1200 by 800 viewport. Verify: Drag through the canvas and sample the flow after release. Check that dye follows the drag, continues swirling, and responds to a second drag in another direction. Use Clear, then drag again to check that a fresh flow can start.

assistant
thinking
Evaluating Canvas2D semi-Lagrangian versus WebGL for a self-contained fluid solver with performance and simplicity tradeoffs.Selecting 144x96 Float32Array grid and Jacobi pressure solve to bound per-frame work for the fluid solver.Extending the solver with vorticity confinement, dissipation, and pointer-driven splats while fixing the grid size.

Building a real swirling fluid-and-dye solver — writing the full app now.

→ write index.html (14635 bytes)
toolResult

Successfully wrote to index.html

assistant
thinking
Fluid sim written — now verifying drags, swirl persistence, and Clear in the browser.
→ browser {"action":"reload"}
toolResult
 
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":"◉ Fluid & Dye\nINK\nSWIRL\nFADE\n⏸ Pause\n✕ Clear\nDrag to stir & paint — momentum keeps swirling after release · double-click for a burst","images":"attached"}
assistant
 
thinking
Diagnosing pixelated canvas rendering by checking drawImage smoothing and DPR scaling issues with small source to large destination.
Initial render shows harsh square edges around blobs — fixing the splat falloff, then testing drags.
→ edit {"edits":[{"newText":"  var R=Math.ceil(rad*2.2);\n  var x0=Math.max(1,Math.floor(sx-R)), x1=Math.min(SIM_W-2,Math.ceil(sx+R));\n  var y0=Ma
toolResult
 
Successfully replaced 1 block(s) in index.html.
assistant
 
thinking
→ edit {"edits":[{"newText":"      if(d2>r2*4.84) continue;\n      var fall=Math.exp(-d2*3*inv);","oldText":"      if(d2>r2*4) continue;\n      var
toolResult
 
Successfully replaced 1 block(s) in index.html.
assistant
 
→ browser {"action":"reload"}
toolResult
 
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.","error: r2 is not defined"],"dom":"◉ Fluid & Dye\nINK\nSWIRL\nFADE\n⏸ Pause\n✕ Clear\nDrag to stir & paint — momentum keeps swirling after release · double-click for a burst","images":"attached"}
assistant
 
thinking
Broke the splat radius in that edit — fixing it.
→ read {"limit":30,"offset":58,"path":"index.html"}
toolResult
 
  <div class="grp"><button id="pause">⏸ Pause</button><button id="clear">✕ Clear</button></div>
</div></div>
<div id="hint">Drag to stir &amp; paint — momentum keeps swirling after release · double-click for a burst</div>
<div id="stats"></div>
<script>
(function(){
"use strict";
// ---- Simulation grid (fixed, bounded work) ----
var SIM_W = 160, SIM_H = 100;
var N = SIM_W*SIM_H;
var u=new Float32Array(N), v=new Float32Array(N);
var u0=new Float32Array(N), v0=new Float32Array(N);
var r=new Float32Array(N), g=new Float32Array(N), b=new Float32Array(N);
var r0=new Float32Array(N), g0=new Float32Array(N), b0=new Float32Array(N);
var p=new Float32Array(N), div=new Float32Array(N);
var curl=new Float32Array(N);
var PRESSURE_ITERS = 22;
var vortStrength = 2.2;   // vorticity confinement
var dyeDecay = 0.10;      // per second
var velDecay = 0.45;      // per second
var SPLAT_RADIUS = 4.2;

function idx(x,y){return x+y*SIM_W;}

function sampleF(f,x,y){
  if(x<0)x=0; if(x>SIM_W-1.001)x=SIM_W-1.001;
  if(y<0)y=0; if(y>SIM_H-1.001)y=SIM_H-1.001;
  var x0=x|0, y0=y|0, x1=x0+1, y1=y0+1;
  var sx=x-x0, sy=y-y0;
  var i00=y0*SIM_W+x0, i10=i00+1, i01=i00+SIM_W, i11=i01+1;

[309 more lines in file. Use offset=88 to continue.]
assistant
 
→ read {"limit":30,"offset":88,"path":"index.html"}
toolResult
 
  var a=f[i00]+(f[i10]-f[i00])*sx;
  var c=f[i01]+(f[i11]-f[i01])*sx;
  return a+(c-a)*sy;
}

// Gaussian splat: velocity += (dx,dy)*falloff, dye += color*falloff
function splat(sx,sy,dx,dy,cr,cg,cb,rad){
  rad = rad||SPLAT_RADIUS;
  var R=Math.ceil(rad*2.2);
  var x0=Math.max(1,Math.floor(sx-R)), x1=Math.min(SIM_W-2,Math.ceil(sx+R));
  var y0=Math.max(1,Math.floor(sy-R)), y1=Math.min(SIM_H-2,Math.ceil(sy+R));
  var inv=r2>0?1/r2:0;
  for(var y=y0;y<=y1;y++){
    for(var x=x0;x<=x1;x++){
      var ddx=x-sx, ddy=y-sy;
      var d2=ddx*ddx+ddy*ddy;
      if(d2>r2*4.84) continue;
      var fall=Math.exp(-d2*3*inv);
      var i=y*SIM_W+x;
      u[i]+=dx*fall; v[i]+=dy*fall;
      r[i]+=cr*fall; g[i]+=cg*fall; b[i]+=cb*fall;
    }
  }
}

function advectVelocity(dt){
  u0.set(u); v0.set(v);
  var diss=Math.exp(-velDecay*dt);
  for(var y=0;y<SIM_H;y++){
    var row=y*SIM_W;

[279 more lines in file. Use offset=118 to continue.]
assistant
 
→ edit {"edits":[{"newText":"  rad = rad||SPLAT_RADIUS;\n  var r2=rad*rad;\n  var R=Math.ceil(rad*2.2);","oldText":"  rad = rad||SPLAT_RADIUS;\n  v
toolResult
 
Successfully replaced 1 block(s) in index.html.
assistant
 
→ browser {"action":"reload"}
toolResult
 
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":"◉ Fluid & Dye\nINK\nSWIRL\nFADE\n⏸ Pause\n✕ Clear\nDrag to stir & paint — momentum keeps swirling after release · double-click for a burst","images":"attached"}
assistant
 
thinking
Seed looks smooth now — testing that drags inject swirling dye that persists.
→ browser {"action":"drag","toX":900,"toY":400,"x":300,"y":400}
toolResult
 
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":"◉ Fluid & Dye\nINK\nSWIRL\nFADE\n⏸ Pause\n✕ Clear\nDrag to stir & paint — momentum keeps swirling after release · double-click for a burst\n56 fps · 160×100 grid","images":"attached"}
assistant
 
thinking
First drag paints a bright streak and the seeded blobs are curling — now checking a second drag and Clear.
→ browser {"action":"drag","toX":600,"toY":650,"x":600,"y":200}
toolResult
 
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":"◉ Fluid & Dye\nINK\nSWIRL\nFADE\n⏸ Pause\n✕ Clear\nDrag to stir & paint — momentum keeps swirling after release · double-click for a burst\n43 fps · 160×100 grid","images":"attached"}
assistant
 
thinking
→ browser {"action":"click","x":918,"y":37}
toolResult
 
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":"◉ Fluid & Dye\nINK\nSWIRL\nFADE\n⏸ Pause\n✕ Clear\nDrag to stir & paint — momentum keeps swirling after release · double-click for a burst\n54 fps · 160×100 grid","images":"attached"}
assistant
 
thinking
Clear wipes the canvas — confirming a fresh flow can start.
→ browser {"action":"drag","toX":850,"toY":500,"x":350,"y":300}
toolResult
 
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":"◉ Fluid & Dye\nINK\nSWIRL\nFADE\n⏸ Pause\n✕ Clear\nDrag to stir & paint — momentum keeps swirling after release · double-click for a burst\n51 fps · 160×100 grid","images":"attached"}
assistant
 
thinking
→ browser {"action":"click","x":835,"y":37}
toolResult
 
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":"◉ Fluid & Dye\nINK\nSWIRL\nFADE\n▶ Resume\n✕ Clear\nDrag to stir & paint — momentum keeps swirling after release · double-click for a burst\n38 fps · 160×100 grid","images":"attached"}
assistant
 
thinking
Pause freezes the flow correctly — resuming and confirming the final file.
→ browser {"action":"click","x":837,"y":36}
→ bash {"command":"ls -la index.html && grep -c \"外部\\|http\" index.html; echo ---; grep -o \"SIM_W = [0-9]*\" index.html"}
toolResult
 
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":"◉ Fluid & Dye\nINK\nSWIRL\nFADE\n⏸ Pause\n✕ Clear\nDrag to stir & paint — momentum keeps swirling after release · double-click for a burst\n38 fps · 160×100 grid","images":"attached"}
toolResult
 
-rw-r--r-- 1 node node 14701 Oct  9 06:43 index.html
0
---
SIM_W = 160

assistant
 
thinking
Done — `index.html` is saved (14.7 KB, fully self-contained, zero network requests).

**What it is:** a Stam-style stable-fluid solver on a fixed 160×100 grid (velocity + RGB dye fields, semi-Lagrangian advection, 22-iteration pressure projection, vorticity confinement for persistent swirl, exponential velocity/dye decay). Dye is rendered from a small offscreen buffer upscaled with smoothing, so per-frame work is bounded (~16k cells) and the UI stays responsive.

**Actually checked in-browser (1200×800):**
- Load: seeded colored blobs with motion visible, no console errors, ~50+ fps.
- Horizontal drag: paints a dye streak following the pointer; seeded blobs deform into spiral curls (advection + swirl, not fading particles).
- Second vertical drag: new streak appears and visibly distorts the first (velocity coupling), dye keeps evolving after release.
- Clear: wipes dye and velocity to black; fresh diagonal drag starts a new flow cleanly.
- Pause/Resume: freezes mid-swirl curls, resumes on click; color picker + swatches, Swirl/Fade sliders present.

**Remaining unverified:** long-term dissipation rate (decays over seconds by design, not timed precisely), touch-pointer behavior on mobile, and performance on slower machines beyond the ~38–56 fps seen here.