Flow-field particles · ling-3.0-flash

Using the pre-provided p5.min.js (global p5, instance or global mode), create a full-screen flow-field particle animation: thousands of particles advected by Perlin-noise vectors, leaving fading trails, with colors shifting over time.

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transcript · 8 messages

user

assistant

thinking

The user wants a full-screen flow-field particle animation using p5.min.js. Let me create a single index.html file with:

1. p5.min.js loaded locally (it's already in the current directory)
2. A flow-field particle system with:
   - Thousands of particles
   - Perlin noise vectors for advection
   - Fading trails
   - Color shifting over time

Let me first check that p5.min.js exists in the current directory.

Let me check for the p5.min.js file and then create the animation

→ bash {"command":"ls /tmp/ws/p5.min.js"}

toolResult

/tmp/ws/p5.min.js

assistant

thinking

Good, p5.min.js exists. Now I need to create a full-screen flow-field particle animation. Let me design this carefully:

1. Use p5.js in instance mode to avoid global pollution
2. Create a flow field using Perlin noise
3. Thousands of particles that follow the flow field vectors
4. Fading trails (using semi-transparent background or storing trail positions)
5. Colors that shift over time (using HSB color mode)

Key design decisions:
- Use `createCanvas(windowWidth, windowHeight)` for full screen
- Flow field: sample Perlin noise at particle positions, map to angle, create vector
- Trails: either use `background(0, 0, 0, 0.05)` for fade effect, or store trail points
- Color shifting: use `colorMode(HSB)` and shift hue over time
- Performance: use `noStroke()` for particles, `blendMode(ADD)` or similar for trails
- Use `push()`/`pop()` for transforms

Let me write this as a single index.html with p5 in instance mode.

For the flow field approach:
- Each particle has a position (x, y)
- Each frame, sample noise at the particle's position (scaled)
- The noise value maps to an angle (0 to TWO_PI)
- Create a vector from that angle
- Add the vector to the particle's velocity
- Update position
- Draw the particle with a trail

For fading trails, I'll use a semi-transparent background each frame (alpha < 255) which creates a natural trail effect.

For color shifting, I'll use HSB mode and increment the hue base over time.

Let me also consider performance with thousands of particles. I'll use:
- Small particle size (1-2px)
- No stroke, just fill
- Batch drawing with `beginShape()`/`endShape()` if needed, but individual points might be fine

Actually, for the best visual effect with trails, I should use the semi-transparent background approach. But that means older trails fade out gradually, which is nice.

Let me write the code:

```javascript
class Particle {
  constructor(x, y) {
    this.pos = createVector(x, y);
    this.vel = createVector(0, 0);
    this.acc = createVector(0, 0);
    this.maxSpeed = 2;
    this.hueOffset = random(360);
  }
  
  update(flowField, scale) {
    // Get flow field vector at particle position
    let x = floor(this.pos.x / scale);
    let y = floor(this.pos.y / scale);
    let angle = noise(x * 0.01, y * 0.01) * TWO_PI * 4;
    let force = p5.Vector.fromAngle(angle);
    force.mult(0.5);
    
    this.acc.add(force);
    this.vel.add(this.acc);
    this.vel.limit(this.maxSpeed);
    this.pos.add(this.vel);
    this.acc.mult(0);
  }
  
  show(hueBase) {
    let h = (this.hueOffset + frameCount * 0.5) % 360;
    fill(h, 80, 90, 200);
    noStroke();
    ellipse(this.pos.x, this.pos.y, 2, 2);
  }
  
  edges() {
    if (this.pos.x < 0) this.pos.x = width;
    if (this.pos.x > width) this.pos.x = 0;
    if (this.pos.y < 0) this.pos.y = height;
    if (this.pos.y > height) this.pos.y = 0;
  }
}
```

Wait, I should think about the flow field more carefully. The noise function in p5 takes x, y, z parameters and returns 0-1. I need to scale the particle coordinates to get meaningful noise values.

Let me also think about the number of particles - "thousands" means at least 2000, maybe 5000-10000.

For performance with 5000+ particles, drawing individual ellipses might be slow. I could use `point()` instead of `ellipse()` for faster rendering.

Let me also consider using `blendMode(ADD)` for a nicer visual effect with the trails.

Here's my plan for the full file:

```html
<!DOCTYPE html>
<html>
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Flow Field Particles</title>
  <style>
    * { margin: 0; padding: 0; }
    body { overflow: hidden; background: #000; }
    canvas { display: block; }
  </style>
</head>
<body>
  <script src="p5.min.js"></script>
  <script>
    // p5 instance mode
    const sketch = (p) => {
      let particles = [];
      const NUM_PARTICLES = 5000;
      const FLOW_SCALE = 4;
      let hueBase = 0;
      
      p.setup = () => {
        p.createCanvas(p.windowWidth, p.windowHeight);
        p.colorMode(p.HSB, 360, 100, 100, 100);
        p.noStroke();
        for (let i = 0; i < NUM_PARTICLES; i++) {
          particles.push(new Particle(p.random(p.width), p.random(p.height), p));
        }
      };
      
      p.draw = () => {
        // Semi-transparent background for fading trails
        p.background(0, 0, 0, 15);
        
        // Shift hue base over time
        hueBase = (hueBase + 0.3) % 360;
        
        for (let particle of particles) {
          particle.update(FLOW_SCALE);
          particle.show(hueBase, p);
          particle.edges(p.width, p.height);
        }
      };
      
      p.windowResized = () => {
        p.resizeCanvas(p.windowWidth, p.windowHeight);
      };
    };
    
    new p5(sketch);
  </script>
</body>
</html>
```

Hmm, let me think more carefully about the flow field. I want smooth, coherent flow patterns. The noise function should be sampled at a scale that creates nice swirling patterns.

Also, I should consider using `p5.Vector.fromAngle()` which is available in p5.js.

Let me also add some visual polish:
- Varying particle sizes based on speed
- Using `blendMode(ADD)` for glowing trails
- Maybe some particles are brighter/larger than others

Actually, let me reconsider the trail approach. Using `background(0, 0, 0, 15)` with alpha creates a nice fade, but it also means the entire canvas fades, not just the trails. This is actually the standard approach for this kind of effect and looks great.

Let me also think about the noise scale. If I use `noise(x * 0.005, y * 0.005)`, the flow field will be very large-scale and smooth. If I use `noise(x * 0.01, y * 0.01)`, it'll be more detailed. I want something in between for nice swirling patterns.

Let me also consider using 3D noise (with a time component) so the flow field evolves over time, creating dynamic patterns.

Here's my refined approach:

```javascript
// Flow field vector at a point
function getFlowField(x, y, t, scale) {
  let angle = noise(x * scale, y * scale, t * scale) * TWO_PI * 4;
  return p5.Vector.fromAngle(angle);
}
```

Using time as the z-component of noise makes the flow field evolve, which is much more interesting.

Let me finalize the code now. I'll aim for about 5000-8000 particles for a good visual density.

One more thing - I should use `p.point()` or `p.ellipse()` for drawing. `point()` is faster but `ellipse()` gives nicer circles. For 5000+ particles, `point()` might be better for performance.

Actually, let me use `p.circle()` which is the modern p5 equivalent and looks good.

Wait, in older p5 versions `circle()` might not exist. Let me use `ellipse(x, y, 2, 2)`.

Let me also add some variety - some particles move faster, some slower, some have different trail lengths.

Here's my final design:

```html
<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Flow Field Particles</title>
  <style>
    * { margin: 0; padding: 0; box-sizing: border-box; }
    html, body { width: 100%; height: 100%; overflow: hidden; background: #000; }
    canvas { display: block; position: fixed; top: 0; left: 0; }
  </style>
</head>
<body>
  <script src="p5.min.js"></script>
  <script>
    const sketch = (p) => {
      let particles = [];
      const NUM = 6000;
      const FLOW_SCALE = 0.003;
      const NOISE_SCALE = 0.003;
      const TIME_SCALE = 0.0005;
      
      class Particle {
        constructor(x, y) {
          this.pos = p.createVector(x, y);
          this.vel = p.createVector(p.random(-1, 1), p.random(-1, 1));
          this.acc = p.createVector();
          this.maxSpeed = p.random(1.5, 4);
          this.hueOffset = p.random(360);
          this.size = p.random(1, 3);
          this.life = p.random(100, 255);
        }
        
        update() {
          let angle = p.noise(
            this.pos.x * NOISE_SCALE,
            this.pos.y * NOISE_SCALE,
            p.frameCount * TIME_SCALE
          ) * p.TWO_PI * 4;
          
          let force = p5.Vector.fromAngle(angle);
          force.mult(0.3);
          
          this.acc.add(force);
          this.vel.add(this.acc);
          this.vel.limit(this.maxSpeed);
          this.pos.add(this.vel);
          this.acc.mult(0);
        }
        
        show() {
          let h = (this.hueOffset + p.frameCount * 0.3) % 360;
          let s = 80;
          let b = 90;
          let a = p.map(p.vel.mag(), 0, this.maxSpeed, 30, 200);
          
          p.fill(h, s, b, a);
          p.ellipse(this.pos.x, this.pos.y, this.size, this.size);
        }
        
        edges() {
          if (this.pos.x < -10) this.pos.x = p.width + 10;
          if (this.pos.x > p.width + 10) this.pos.x = -10;
          if (this.pos.y < -10) this.pos.y = p.height + 10;
          if (this.pos.y > p.height + 10) this.pos.y = -10;
        }
      }
      
      p.setup = () => {
        p.createCanvas(p.windowWidth, p.windowHeight);
        p.colorMode(p.HSB, 360, 100, 100, 100);
        p.noStroke();
        p.blendMode(p.ADD);
        
        for (let i = 0; i < NUM; i++) {
          particles.push(new Particle(p.random(p.width), p.random(p.height)));
        }
      };
      
      p.draw = () => {
        p.background(0, 0, 0, 20);
        
        for (let particle of particles) {
          particle.update();
          particle.show();
          particle.edges();
        }
      };
      
      p.windowResized = () => {
        p.resizeCanvas(p.windowWidth, p.windowHeight);
      };
    };
    
    new p5(sketch);
  </script>
</body>
</html>
```

Wait, I need to be careful with `blendMode(ADD)` and the background. With ADD blend mode, the background alpha might not work as expected. Let me think...

Actually, `blendMode(ADD)` with a semi-transparent background can create nice glowing effects. But it might also cause the canvas to get too bright over time. Let me test this logic...

With ADD blend mode:
- Each frame, we draw a semi-transparent black background (adds a little black)
- Then we draw particles with additive blending (brightens)
- This should create nice glowing trails

Actually, the issue is that with ADD mode, `background(0,0,0,20)` adds 20 units of darkness to everything, which is fine. And particles add brightness. This should work well for a glowing trail effect.

But wait - there's a subtlety. In p5.js, `blendMode(ADD)` affects how new drawings are composited with the existing canvas. The `background()` function always clears the canvas first, so blend mode might not affect it. Let me reconsider...

Actually, in p5.js, `background()` with alpha does work as a semi-transparent overlay when blend mode is set. But I'm not 100% sure. Let me use a different approach that's more reliable:

Instead of relying on blendMode(ADD) with background alpha, I could:
1. Draw particles with `blendMode(ADD)` for glow
2. Use `background(0)` each frame (full clear) but draw trails manually

Or better yet, let me use the standard approach:
1. `background(0, 0, 0, 25)` - semi-transparent black for trails
2. Draw particles normally (no blend mode)
3. Use `p.fill()` with alpha for particle transparency

This is simpler and more reliable. The trails will fade naturally.

Actually, let me reconsider. The `blendMode(ADD)` approach with semi-transparent background is a well-known technique in p5.js for flow field visualizations. It works because:
- `background(r, g, b, a)` in p5.js draws a rectangle with the specified alpha over the entire canvas
- With ADD blending, this adds the alpha value to existing pixels
- Since the background is dark (0,0,0), it effectively darkens slightly, creating the trail fade

Hmm, actually I think I'm overcomplicating this. Let me just use the simple approach:

1. No blend mode (default)
2. Semi-transparent background each frame for trails
3. Particles drawn with fill color and alpha

This will look great and be reliable.

Let me also reconsider the number of particles. 6000 should be fine for most browsers.

Let me finalize and write the code. I want it to be visually stunning with:
- Smooth flow field
- Beautiful color shifting
- Nice fading trails
- Good performance

One more consideration: I should use `p5.Vector` from the p5 instance, not the global p5. In instance mode, I need to use `p.createVector()` etc.

Let me also add some mouse interaction - particles could be attracted to or repelled from the mouse position, making it more interactive.

Actually, the user didn't ask for mouse interaction, so let me keep it simple and focused on the core requirements: flow field, Perlin noise, fading trails, color shifting.

Let me write the final version:

Now I'll create the full-screen flow-field particle animation.

→ write /tmp/ws/index.html (3067 bytes)

toolResult

Successfully wrote 3067 bytes to /tmp/ws/index.html

assistant

thinking

The file has been written. Let me verify it looks correct by reading it back, and also check that p5.min.js is present.

Let me verify the file is correct and complete.

→ bash

{"command":"wc -l /tmp/ws/index.html && head -5 /tmp/ws/index.html && echo \"---\" && tail -5 /tmp/ws/index.html && echo \"---\" && ls -la /

toolResult

104 /tmp/ws/index.html <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> --- new p5(sketch); </script> </body> </html> --- -rw-r--r--. 1 node node 1034532 Aug 1 16:57 /tmp/ws/p5.min.js

assistant

thinking

The file looks good. Let me verify it's a complete, valid HTML file by checking the structure. It has:
1. DOCTYPE and html tags
2. p5.min.js loaded locally
3. p5 sketch in instance mode
6000 particles with Perlin noise flow field
Fading trails via semi-transparent background
Color shifting via HSB mode with time-based hue rotation
Window resize handling

Everything looks correct. The file is self-contained with no external resources.

The file is complete and valid. Here's a summary of what's in `/tmp/ws/index.html`: **Flow Field Particle Animation** — single self-contained file, no external resources. | Feature | Implementation | |---|---| | **Flow field** | 3D Perlin noise (`noise(x·s, y·s, t·s)`) sampled at each particle's position, mapped to an angle producing a smooth vector field that evolves over time | | **Particles** | 6,000 particles, each with position, velocity, acceleration, and individual max speed/hue offset | | **Advection** | Each frame, noise-derived force is applied → velocity updated → position advanced → velocity clamped | | **Fading trails** | Semi-transparent black background (`alpha=18`) each frame naturally erases old positions | | **Color shifting** | HSB color mode; hue cycles over time (`hueOffset + frameCount × 0.25`), brightness/size modulated by speed | | **Full-screen** | `createCanvas(windowWidth, windowHeight)` + `windowResized` handler | | **Edge wrapping** | Particles wrap around screen edges for seamless infinite flow | | **Instance mode** | Uses `new p5(sketch)` with the `p` parameter throughout — no global pollution |

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

modelling-3.0-flash

vendorinclusionai

harnesspi-agent

generated2026-08-01

EVALUATION

★★★★★ 4/5 working

Flow-field particle trails with rainbow colors constantly animate; inputs don't change behavior but self-animation is strong.

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.

idle motion18.8%

on click15.7%

on drag17.8%

on wheel11.9%

on enter + space12.0%

on arrow keys10.2%

on w/a/s/d10.3%

frame spread18.4 / 255

console errors0

js errors none

METRICS

runtime21.8s

tokens in17k

tokens out5.4k

cached2.0k

cost / run$0.0000