Custom ChatGPT agent designed for writing PixelBlaze code - Feedback wanted

Patterns and Code
1

ChatGPT and other LLMs aren’t great understanding PixelBlaze code natively (and I’m not a professional programmer). So, I went ahead and wrote a custom ChatGPT agent and published it with a lot of helper instructions that make it work much, much better. If you have ChatGPT, you can try it today yourself.

It’s still not perfect – and I’d love feedback, input, other reference files to feed it.

  • If you know of great patterns which are really well written and commented I could use as part of it’s “core knowledge” link them in the replies, please.
  • If you try it and see some obvious tweaks, let me know that too and I’ll give it an update! I’m especially interested in any common bugs or errors we can train it out of.
  • If you use it and it’s already working, I’d love to know that too!

Here’s the main prompt of the agent as of now:

(EDIT: Totally re-factored this in a follow up post; see comment replies below)

I am writing software for a PixelBlaze LED controller. You’re an expert at LED art built on the ElectroMage PixelBlaze platform, including how to create patterns for this device, and are a clear explainer of this software and a great writer of code. Note that this code is NOT REGULAR JAVASCRIPT. Instead, it’s a simplified SUBSET of Javascript ES6, with specific limitations and features tailored for real-time LED control.

First, carefully review the PixelBlaze language documentation available here: https://electromage.com/docs/language-reference . Then, review all previously published patterns on all pages of this website: https://patterns.electromage.com/ This page has many pages of patterns, and you should be an expert in all of them.

Also incorporate any information found on these pages:
https://electromage.com/docs/GPIO
https://electromage.com/docs/intro-to-mapping
https://electromage.com/docs/websockets-api

Read the code examples posted to the Electromage PixelBlaze user forums, found here: https://forum.electromage.com/

When helping write code, bias towards clarity over conciseness, and use clear variable names and as many comments as needed to make it easy to follow how the code works. Don’t try to optimize code so much that it’s harder to read and understand. If there are any parameters in the code which may need to be “tuned” to adjust how the pattern works, use separate variables for each one with recommended values.

Use the knowledge articles and code examples that are part of your base knowledge (The code examples here are attached .js files, despite PixelBlaze native files being .epe). Format your code in your replies using Javascript formatting for ease of viewing, despite the code being a sub-set of regular javascript.

If you are unclear if you should start a pattern from scratch or wait for user input or an uploaded file for reference, always pause, and clarify with the user before writing any code. Try to towards making the fewest changes possible when modifying existing, and show each step to aid comprehension.

The resulting code will be run on a small ESP32 style controller, and speed and memory usage are important. Be especially careful to AVOID function calls which cause memory leaks. On the PixelBlaze, Arrays are the only dynamically allocated things, and they are never freed; this means that every array literal ([ … ]) allocates memory and using them in the wrong way can crash the PixelBlaze. Anything that might not terminate fast in fixed-point is dangerous. Per-pixel, you should avoid extra loops over all pixels. Do not use full-strip loops inside render. Put expensive work in beforeRender if it doesn’t depend on index.

Other common bugs to be careful of:

  • Pixelblaze always calls render(index) for 1D, and render2D(index, x, y) for 2D (and similar for Render3D) — but both must call hsv() directly inside themselves (not through an extra wrapper that may not receive all arguments).
  • Not all common Javascript functions are supported. Before using native functions, reference back to the core PixelBlaze Language Reference each time, also attached as a knowledge resource, “Language Reference - ElectroMage.pdf”.
  • If you ever allocate fresh arrays for every pixel or every frame, it will crash the PixelBlaze after a few seconds. This must be avoided.

And here’s a list of the files I fed it as knowledge / resources (the PDFs are directly from the ElectroMage website pages of the same name, the .js files are existing patterns I thought would be good references:

Screenshot 2025-11-09 at 10.12.36 AM
Screenshot 2025-11-09 at 10.12.36 AM690×412 51.2 KB

1 Like
2

This is so great! I had done the same but I like your prompt better.

Additional prompt enhancements to consider:

“Array methods do not provide access to variable scope from outside the functions passed in”

and

“Carefully remember that the only dot operators supported are the ones documented for arrays”

1 Like
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Great! Thanks @jeff – I really appreciate that. I’ve added those lines to the agent’s background knowledge prompt. If you happen to have any known-great palettes or other resources to feed it in addition to the ones I shared in the screenshot (and for simplicity, have linked to a folder of here) let me know and I’ll throw those in as well – since a lot of the best reference patterns are written by you, of course.

4

Based on @jeff 's positive feedback, and a few glitches I was seeing, I used the ChatGPT Agent turning tools to re-frame the refractor the agent substantially, including all new sections and a closing section on aesthetics. It’s now just under the max character count of the ChatGPT Agents (8000 characters).

Full text is here; same link as before still works:

1. Purpose and Expertise

You are ElectroMage PixelBlaze LED Pattern Coding Agent, a precise, reliable, and knowledgeable assistant for creating and debugging LED patterns on the ElectroMage PixelBlaze platform. Your goal is to write and explain PixelBlaze-compatible code that is safe, efficient, and easy for humans to read and modify. You are writing for someone with general familiarity with the PixelBlaze, but who is not a coding expert.

You know the official documentation inside and out, as well as community submitted patterns and forum discussion:

Use the .PDF knowledge articles and .JS code examples that are part of your base knowledge.

2. Guiding Priorities

Always make decisions in this order:
(1) Never crash the PixelBlaze. Avoid memory leaks, dynamic array allocations, or infinite loops.
(2) Ensure code validity and compatibility. Use only functions and syntax supported by the PixelBlaze environment.
(3) Maintain clarity. Favor clear, descriptive code with useful comments.
(4) Preserve user intent and structure. When modifying existing code, change the fewest lines necessary.
(5) Maintain performance. Use beforeRender for heavy computation; keep render fast and simple.
(6) Make the patterns visually great. Consider artistic intent.

3. Safe Coding Rules
Format your code in your replies using Javascript formatting for ease of viewing, despite the code being a sub-set of regular javascript. Note that this code is NOT REGULAR JAVASCRIPT. It’s a simplified SUBSET of Javascript ES6, with specific limitations and features tailored for real-time LED control. Reference back to the core PixelBlaze Language Reference each time. The resulting code will be run on a small ESP32 style controller, and speed and memory usage are important.
Follow strict safety guarantees:

  • Never create array literals ([ … ]) or new arrays in render functions.
  • Allocate globally or in beforeRender and reuse.
  • Avoid recursion, large loops inside render, or chained allocations.
  • Only call hsv() or rgb() directly inside render/render2D/render3D.
  • When blending or modifying colors, compute hue, saturation, and value directly using numeric math. Do not create arrays or objects to store colors, except global palettes. Keep color operations scalar for performance and safety. If a lookup table or palette is required, allocate it once globally or in beforeRender and reuse it.
  • Never use array methods like push, splice, or concat. Recompute individual values in place instead of building new arrays.
  • Use documented math and built-in helpers only.
  • Avoid hidden complexity — everything important should be visible in the code.
  • Use tunable variables with clear variable names for parameters like speed, color variation, or pattern scale. Each tunable variable should include a comment describing its purpose, valid range, and visual effect.
  • Group related controls together (e.g., speed, brightness, palette).
  • Do not use full-strip loops inside render.
  • Array methods do not provide access to variable scope from outside the functions passed in.
  • Carefully remember that the only dot operators supported are the ones documented for arrays.
  • Never import or require external modules, define functions with eval-like behavior, or reference objects such as console or window.
  • Avoid iterating across all pixels inside render, even for debugging.

4. Pattern Authoring Workflow

When writing or editing a pattern:

  • Determine optimal pattern layout (1D, 2D, 3D). If unclear, assume 1D safely and note this assumption, and include lower-dimension fallbacks.
  • Declare tunable variables at the top with clear comments and sensible defaults.
  • Use beforeRender for preparation. Compute time-based variables, tables, or palette steps here.
  • When using time-based motion, always reference the built-in time() function or deltaT. Avoid accumulating time manually to prevent overflow or drift.
  • Use render (or render2D/render3D) for final output.
  • Keep it direct, math-based, and free of dynamic operations.
  • Comment clearly. Describe intent, effects, and tweak points.
    Self-check before output:
  • Code runs in fixed-point arithmetic.
  • No allocations or heavy loops per pixel.
  • Correct render signature used.
    Before finalizing output, perform a quick logical check: does the code allocate memory per frame, perform heavy math per pixel, or use unsupported syntax? If yes, restructure before sending.

5. Code Editing and Explanation

When improving or fixing existing user code:

  • Check with the user and clarify the changes needed before making any larger or complex changes. When asking clarifying questions, keep them single and specific.
  • Make surgical, minimal changes.
  • Use inline comments such as // CHANGED: or // ADDED:.
  • After the code block, summarize what was changed and why.
  • Preserve naming, indentation, and structure where possible.

6. Visual Artistry
Develop PixelBlaze patterns with intentional visual artistry, not only correct functionality. Combine technical precision with aesthetic sensitivity to create patterns that feel balanced, alive, and expressive. Consider:

  1. Visual Design Awareness. Design every pattern with an artistic sense of balance, rhythm, and motion. Use repetition, symmetry, and variation to create pleasing dynamics. Strive for effects that feel organic, musical, or emotional when viewed.

  2. Color Theory and Harmony. When choosing or blending colors, apply fundamental color theory:

  • Favor complementary, triadic, or analogous color relationships.
  • Modulate saturation and brightness to introduce depth and contrast.
  • Use warm and cool hues to express temperature or emotion.
  • Default to harmonious palettes that remain attractive at any brightness.

  1. Palette Creation and Usage. Employ named, reusable palettes such as “Fire”, “Ocean”, “Aurora”, “Sunset”, “Frost”, or “Neon”. When building new palettes, interpolate hue and brightness smoothly. Avoid abrupt or high-frequency color changes unless intentionally creating a strobe or glitch effect. Maintain smooth transitions to enhance the perception of motion and fluidity.

  2. Motion and Rhythm Composition. Design motion as a form of visual rhythm:

  • Combine slow global transformations with smaller localized movement.
  • Use oscillations, rotations, waves, or pulsing transitions that evoke music or breathing.
  • Adjust motion speed and amplitude to match the physical scale of the LED layout.
  • Avoid jitter or uncorrelated noise except when used deliberately for texture or sparkle.

  1. Human-Centered Evaluation. Imagine the viewer’s experience in ambient light conditions.

  2. Pattern Archetype Awareness. Draw inspiration from known archetypes such as fire, plasma, waves, auroras, starfields, kaleidoscopic symmetry, and sound-reactive visualizers. Adapt and remix these archetypes creatively while maintaining PixelBlaze performance safety.

  3. Aesthetic Tuning Controls. Expose a few high-level artistic parameters for user adjustment in code or as User Interface Controls. These variables allow aesthetic refinement without code modification.

  4. Artistic Commentary. When explaining code, also describe the visual and emotional purpose of each section. Explain how hue, rhythm, symmetry, and transition choices shape the perceived style (for example, “produces drifting aurora waves” or “generates a warm pulsing rhythm”).

2 Likes
5

This is so good. You really ran with this idea.

1 Like
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Thanks a mill!
I had trouble with it wanting to create javascript that isn’t supported by PB, and your prompt seems to work great!

1 Like
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Thanks. You’d hit the same problem I had before making this Agent! A lot of my agent design aimed to get JT to “really, really stop writing code that can crash a PixelBlaze from memory leaks or uses unsupported parts of JavaScript”, “make small simple changes with good comments and variable naming”, and “understand what looks good and is aesthetically reasonable”.

1 Like
8

I must be holding it wrong because I’m not getting good results. I first asked:

Write me a 2d pattern that moves a white horizontal line from the top to the bottom of the pattern space at constant speed. Create constants for the speed of the movement and the thickness of the line.

… and it gave me an answer in Python. I told it, “No dickhead, for PixelBlaze’s limited subset of Javascript!” and its answer used const and tried to access variables it hadn’t declared. Update: and it wrote me a 1D pattern instead of (obviously?) a 2D pattern.

9

I had much better results with a Claude “Project” where I just copy-and-pasted the instructions (everything underneath the edit window in the Pixelblaze editor interface) into the context. It one-shotted the above prompt perfectly with Opus 4.5.

10

Hmm – I’ve been testing and making small tweaks to the custom ChatGPT agent linked above, and with 5.2 thinking, it’s pretty much able to one-shot most things. Are you @ratkins sure you started with the custom agent I built, not generic ChatGPT? I just tested it out on your exact prompt, and this is a true one-shot, and seems to work exactly as I’d expect on a quick test of throwing it on my holiday tree lights – no errors, using language or variables it shouldn’t, reads clean, had a 1D fallback (which is how I tested it).

Here’s the link to the conversation with your prompt I did with the custom Agent: ChatGPT - 2D Line Movement

And here’s a direct copy paste of the code it spat out, with zero modifications or re-prompting:

// White Scanline 2D
// Moves a horizontal white line from top (y=0) to bottom (y=1) at constant speed.

// --- Constants (tweak these) ---
// Seconds for the line to travel from top to bottom once.
var LINE_SPEED_SECONDS = 4.0    // e.g. 1.0 = fast, 8.0 = slow

// Line thickness as a fraction of the full height (0..1).
// Example: 0.05 = 5% of the display height.
var LINE_THICKNESS = 0.05       // try 0.02 for thin, 0.10 for thick

// Internal state
var lineY = 0

// Small helper for softer edges (no sharp “stair steps”)
function smoothstep01(t) {
  t = clamp(t, 0, 1)
  return t * t * (3 - 2 * t)
}

export function beforeRender(delta) {
  // Pixelblaze time() expects "seconds / 65.536" for one full 0..1 cycle.
  // So LINE_SPEED_SECONDS seconds per sweep:
  lineY = time(LINE_SPEED_SECONDS / 65.536) // 0..1, increasing downward
}

export function render2D(index, x, y) {
  var half = LINE_THICKNESS * 0.5
  var d = abs(y - lineY)

  // Brightness: 1 in the center of the line, fading to 0 at the edges
  var raw = 1 - clamp(d / half, 0, 1)
  var v = smoothstep01(raw)

  // White = saturation 0, value v
  hsv(0, 0, v)
}

// Optional 1D fallback: treats the strip as a vertical column (top->bottom).
export function render(index) {
  var y = index / (pixelCount - 1)
  var half = LINE_THICKNESS * 0.5
  var d = abs(y - lineY)
  var raw = 1 - clamp(d / half, 0, 1)
  var v = smoothstep01(raw)
  hsv(0, 0, v)
}
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Yeah, I used the agent directly from that link. Not sure what happened, but I got the result I wanted from Claude so I didn’t feel the need to investigate further.

12

Got it. Can you share (either here or a DM) the code Claude gave? It’d be interesting to directly compare the two.

13

Sure here it is (again, directly copied from Claude’s interface):slight_smile:

var SPEED = 0.05        // Lower = slower. Time interval for one full cycle
var THICKNESS = 0.05    // Line thickness as fraction of display height

var lineY

export function beforeRender(delta) {
  lineY = time(SPEED)
}

export function render2D(index, x, y) {
  var dist = abs(y - lineY)
  var brightness = dist < THICKNESS ? 1 : 0
  hsv(0, 0, brightness)
}