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Mandelbrot explorer · step-3.7-flash

Render the Mandelbrot set with a smooth color gradient on a full-screen canvas, with click-and-drag to pan and mouse-wheel to zoom.

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transcript · 4 messages
user

Render the Mandelbrot set with a smooth color gradient on a full-screen canvas, with click-and-drag to pan and mouse-wheel to zoom.

assistant
thinking
The user wants a single-page web app that renders the Mandelbrot set on a full-screen canvas with:
1. Smooth color gradient
2. Click-and-drag to pan
3. Mouse-wheel to zoom

All in one self-contained `index.html` file with inline CSS and JS, no external resources.

Let me create a high-quality Mandelbrot renderer:

Key features:
- Full-screen canvas
- Smooth coloring using the escape-time algorithm with normalized iteration count (renormalization) for smooth gradients
- Pan via click and drag
- Zoom via mouse wheel (zooming towards mouse position)
- Use HSL color mapping for smooth gradient

Technical details for smooth coloring:
- Use the renormalization technique: `mu = iter + 1 - log(log(|z|)) / log(2)`
- This gives continuous values instead of discrete bands

Interaction:
- Mouse drag pans the view
- Mouse wheel zooms in/out centered on mouse position
- Maybe add a double-click to reset view

I'll optimize with requestAnimationFrame and only re-render when needed.

Let me write this.
write /workspace/index.html (5791 bytes)
toolResult

Successfully wrote 5791 bytes to /workspace/index.html

assistant
thinking
The user didn't ask a follow-up question, so I should provide a synopsis of what I just created.

`index.html` is written. Here's what's inside: - **Full-screen canvas** rendering the Mandelbrot set with a smooth HSL colour gradient. - **Smooth colouring** uses the standard renormalization formula (`mu = iter + 1 - log(log(|z|)) / log(2)`) so there are no ugly banding lines. - **Click and drag** to pan across the complex plane. - **Mouse wheel** to zoom in and out, centered on the cursor position. - **Double-click** resets to the default view. - **Cardioid/bulb check** skips obvious interior points for a small speedup. - **`requestAnimationFrame` batching** so interaction stays responsive. Open the file in any modern browser—no server or internet connection required.

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

modelstep-3.7-flash
vendorStepFun
harnesspi-agent
generated2026-07-22

EVALUATION

4/5 working

Mandelbrot renders with smooth gradient colors; drag pans and wheel zooms correctly, no idle animation.

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 motion0.0%
on click0.0%
on drag90.0%
on wheel25.9%
on enter + space0.0%
on arrow keys0.0%
on w/a/s/d0.0%
frame spread71.8 / 255
console errors0
js errors none

METRICS

runtime22.3s
tokens in4.1k
tokens out2.3k
cached1.3k
cost / run$0.0036