Flow-field particles · gemma-4-26b-a4b-it
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.
transcript · 6 messages
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.
thinking
The user wants a single-page web app in `index.html` using `p5.min.js`. The app should be a full-screen flow-field particle animation. Features: - Thousands of particles. - Advected by Perlin-noise vectors. - Fading trails. - Colors shifting over time. - Single file `index.html`. - Use `p5.min.js` provided in the current directory. - No external resources/CDNs. First, I need to check if `p5.min.js` is indeed in the current directory.
{"command":"ls p5.min.js"}p5.min.js
thinking
Okay, `p5.min.js` is present.
Now I will design the `index.html`.
Plan for `index.html`:
- `<html>` structure.
- `<style>` tag for full-screen canvas and reset.
- `<script src="p5.min.js"></script>`
- `<script>` tag containing the p5.js code.
p5.js code details:
- `setup()`:
- `createCanvas(windowWidth, windowHeight)`
- `background(0)`
- Initialize particles.
- `draw()`:
- Semi-transparent background overlay for trails: `background(0, some_alpha)`.
- Update and display particles.
- Shift color over time (e.g., using HSB mode).
- `Particle` class:
- `pos`: current position.
- `vel`: velocity.
- `acc`: acceleration.
- `maxSpeed`.
- `color`.
- `update()`:
- Get noise value at `pos.x, pos.y`.
- Convert noise value to angle.
- Apply force.
- Update pos/vel.
- `edges()`: wrap around screen.
- `show()`: draw a small point or line.
Wait, for "thousands of particles", I should optimize. Using `point()` is fast. Using lines might look better but can be slower if there are too many.
Let's refine the Particle class:
- `pos`
- `vel`
- `acc`
- `maxSpeed`
- `color` (or just use a global hue)
Actually, for "colors shifting over time", I can use HSB color mode.
Let's write the code.
```javascript
let particles = [];
const numParticles = 2000;
const noiseScale = 0.01;
let hueOffset = 0;
function setup() {
createCanvas(windowWidth, windowHeight);
colorMode(HSB, 360, 100, 100, 100);
background(0);
for (let i = 0; i < numParticles; i++) {
particles.push(new Particle());
}
}
function draw() {
// Fading trails
background(0, 0, 0, 5);
hueOffset = (hueOffset + 0.5) % 360;
for (let p of particles) {
p.update();
p.edges();
p.show();
}
}
function windowResized() {
resizeCanvas(windowWidth, windowHeight);
background(0);
}
class Particle {
constructor() {
this.pos = createVector(random(width), random(height));
this.vel = createVector(0, 0);
this.acc = createVector(0, 0);
this.maxSpeed = random(1, 3);
this.h = 0;
}
update() {
let angle = noise(this.pos.x * noiseScale, this.pos.y * noiseScale) * TWO_PI * 4;
let force = p5.Vector.fromAngle(angle);
force.setMag(0.5);
this.applyForce(force);
this.vel.add(this.acc);
this.vel.limit(this.maxSpeed);
this.pos.add(this.vel);
this.acc.mult(0);
}
applyForce(force) {
this.acc.add(force);
}
edges() {
if (this.pos.x > width) this.pos.x = 0;
if (this.pos.x < 0) this.pos.x = width;
if (this.pos.y > height) this.pos.y = 0;
if (this.pos.y < 0) this.pos.y = height;
}
show() {
// Use a color that shifts with time and position/velocity perhaps?
// Or just follow the global hueOffset.
let h = (hueOffset + (this.pos.x / width) * 60) % 360;
stroke(h, 80, 100, 50);
strokeWeight(1);
point(this.pos.x, this.pos.y);
}
}
```
Actually, `background(0, 0, 0, 5)` might not work exactly as intended if I want it to be truly "fading trails" with alpha. In HSB mode, the parameters are H, S, B, A.
If I want to fade the background, I should use a black background with low alpha.
Wait, `background(0, 0, 0, 5)` where 5 is alpha.
In HSB: `colorMode(HSB, 360, 100, 100, 100)`. So 5 is 5% opacity.
Let's make it more visually interesting.
I'll increase the number of particles to 5000.
One thing to consider: `noise()` in p5.js is Perlin noise.
Let's write the full `index.html`.
index.html (3043 bytes)Successfully wrote 3043 bytes to index.html
thinking
The code is written. I should double check the requirements. - "single-page web app": Yes. - "write it ALL into one self-contained file named index.html": Yes. - "CSS in a <style> tag, JS in a <script> tag, inline": Yes. - "Use NO external resources, CDNs or network requests": Yes, I used `p5.min.js` from the local directory. - "load each with a plain <script src="NAME"></script> using its exact filename": Yes. - "full-screen flow-field particle animation": Yes. - "thousands of particles advected by Perlin-noise vectors": Yes (4000). - "leaving fading trails": Yes (via `rect(0, 0, width, height)` with low alpha). - "colors shifting over time": Yes (`hueOffset`). The `noiseScale` and `force.setMag` might need some fine-tuning for the "best" look, but the current values seem reasonable for a start. I'll just verify the file content one more time to ensure I didn't miss anything. The `fill(0, 0, 0, 10)` in `draw()` uses HSB mode because I set `colorMode(HSB, 360, 100, 100, 100)`. In HSB mode: - `fill(0, 0, 0, 10)` means Hue 0, Saturation 0, Brightness 0, Alpha 10. This is black with 10% opacity. Correct. One small detail: `this.pos.x * noiseScale`. If `noiseScale` is `0.005`, and `width` is `1920`, then `x * noiseScale` is around `9.6`. This is fine for Perlin noise. I'm confident with the solution.
I have created a self-contained `index.html` file that implements a high-performance flow-field particle animation using `p5.min.js`. ### Key Features: - **Flow Field**: Particles are moved by a 2D Perlin noise field, creating organic, fluid-like movement. - **Fading Trails**: Instead of clearing the background every frame, a semi-transparent black rectangle is drawn, allowing particles to leave elegant, decaying trails. - **Dynamic Coloring**: Colors cycle through the HSB spectrum over time, with a slight spatial variation based on the particle's position. - **Optimized Performance**: Uses thousands of particles (4,000) rendered as points for smooth animation. - **Fully Self-Contained**: Uses the local `p5.min.js` and contains all CSS and JS within the single HTML file. ```html <!-- index.html contents summary --> <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Flow Field Particle Animation</title> <style> body { margin: 0; padding: 0; overflow: hidden; background-color: #000; } canvas { display: block; } </style> </head> <body> <script src="p5.min.js"></script> <script> // ... p5.js implementation ... </script> </body> </html> ``` The file `index.html` is now present in your current directory.
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
Flowing colorful particle trails animate continuously via Perlin noise, with color shifting over time; inputs don't visibly interact.
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.