Monochrome particle

Monochrome Particle

Portability

This package is not Cursor-specific. It is a portable SKILL.md plus supporting Markdown and a TypeScript example. Use it anywhere the model can read files or pasted instructions:

• Cursor: project or user .cursor/skills/monochrome-particle/, or npx skills add itsyuvallavi/monochrome-particle when supported.
• Other IDEs and agents: follow that product’s documented location for skills, rules, custom instructions, or repository context; if none exists, attach SKILL.md and reference.md to the chat or add them to your project’s agent configuration file.

Tool-specific install mechanics may differ; the implementation contract (customization surface, shaders, cleanup) does not.

Scope

Build a background-only React/Next.js component that owns a fixed full-viewport canvas, WebGLRenderer, layered THREE.Points, buffer geometry with delay and particleDist attributes (never name an attribute distance; it clashes with the GLSL builtin distance()), vertex + fragment shaders, circular sprite texture, animation loop, resize handling, visibility handling, and full WebGL cleanup. Use an orthographic camera whose left/right/top/bottom match the particle grid bounds (viewport half-size plus the same edge buffer used for the grid) so the field always fills the drawable area without perspective frustum clipping (black side gutters).

Do not implement or document these as part of this skill:

• SandstormProvider, sandstorm-transition, stormIntensityRef, or syncing storm intensity to routes
• "Explore work" or any other button driving the background or navigation
• contentOpacityFromStormIntensity or fading page chrome with storm
• Any Next.js transition tied to clicking a CTA

If a source implementation contains storm shader code, remove it or keep uStormIntensity fixed at 0. Do not add context providers or navigation triggers.

Customization Contract

Every implementation generated from this skill must expose a simple prop or config API so future LLM requests can safely change the visual result without editing raw shader constants.

Required customization surface:

• colors: three gradient stops (start, mid, end) as hex strings or RGB values
• speed: animation speed multiplier
• direction: { x, y } flow vector used by the wave shader
• density: particle density multiplier; changing it rebuilds geometry
• pointSize: point-size multiplier
• opacity: alpha multiplier
• zoom: orthographic “camera zoom” (1 = full half-extents; larger values zoom in / center crop). Shipped example default 1.9. Update the frustum when this changes; no particle rebuild required.

Prefer shader uniforms for runtime-safe visual changes:

• uColorStart, uColorMid, uColorEnd
• uFlowDirection
• uPointSizeMultiplier
• uOpacityMultiplier

When the user asks "make it blue and gold", "slow it down", "reverse direction", "make it denser", "make the dots smaller", or similar, edit the config/props first. Do not ask the user to edit GLSL constants for common visual changes.

Optional JSON (or other static config) file

The contract is props on MonochromeDotsBackground (or equivalent). A separate file is not required for correctness.

For demos, Vite apps, or “tune without touching JSX” workflows, it is recommended to keep the same keys in a JSON file (e.g. src/particle-config.json or src/config/backgroundConfig.json), import it in the app root, and spread or pass fields as props. In TypeScript, enable resolveJsonModule: true in the app tsconfig when importing JSON.

Example shape (matches DEFAULT_CONFIG in reference.md):

{
  "colors": { "start": "#14b8d2", "mid": "#b066ec", "end": "#ec599e" },
  "speed": 1.5,
  "direction": { "x": 1, "y": 0.2 },
  "density": 1,
  "pointSize": 1,
  "opacity": 1,
  "zoom": 1.9
}

Implementation Recipe

• Use a "use client" React component with useEffect and useRef (Next.js App Router); in Vite or CRA you can omit the directive.
• If you mirror props into a ref for the animation loop, derive the object with useMemo and assign ref.current inside useEffect. Do not write to ref.current during render — React 19’s ESLint plugin reports that as “Cannot access refs during render”.
• Install three and @types/three.
• Use OrthographicCamera with left, right, top, bottom set each rebuild to ±(width/2 + buffer) and ±(height/2 + buffer) using the same buffer as the particle grid margin. Position the camera on +Z (e.g. 500) and lookAt(0,0,0). Trade-off: no perspective foreshortening; the field looks slightly flatter than with a perspective camera.
• Drawable CSS size: implement readDrawableCssSize(canvas) and use its width/height for grid math, orthographic frustum updates, and renderer.setSize. Take the maximum (per axis) of: canvas.clientWidth, getBoundingClientRect() width/height, window.innerWidth/innerHeight, document.documentElement.clientWidth/clientHeight, and visualViewport width/height when defined—so the buffer is never narrower than the painted layout when innerWidth lags split sidebars, mobile chrome, or first paint.
• Wrap the canvas in a full-bleed layout box: e.g. position: fixed; inset: 0; width: 100dvw; height: 100dvh (or equivalent), and make the canvas position: absolute; inset: 0; width/height: 100%; display: block; max-width: none; margin: 0; padding: 0. Layout owns display size; the renderer must not use setSize(..., true) (do not let Three.js set inline canvas dimensions that fight CSS).
• Use WebGLRenderer with powerPreference: "high-performance", alpha: false, depth: false, stencil: false, and capped DPR (Math.min(devicePixelRatio, 2)).
• Call renderer.setSize(width, height, false) where width/height come from readDrawableCssSize(canvas).
• Build 2 to 3 particle layers using BufferGeometry, ShaderMaterial, THREE.Points, and additive blending. Set points.frustumCulled = false so large gl_PointSize does not disappear at the frustum edge.
• Generate a 32x32 radial-gradient canvas texture for soft circular particles.
• Use distance from the top-left plane origin for the cyan/purple/pink-style gradient, but keep actual colors configurable through uniforms.
• Animate with requestAnimationFrame, time deltas, and a capped delta to avoid jumps after tab inactivity.
• Skip rendering while the tab is hidden.
• Update common visual props (colors, speed, direction, pointSize, opacity) through refs/uniforms without recreating the WebGL renderer. Update zoom by changing the orthographic frustum (same drawable width/height; divide half-extents by zoom), not by rebuilding points.
• Rebuild particle geometry on density changes or whenever drawable size changes. Debounce rapid ResizeObserver callbacks with requestAnimationFrame. On first mount, run two nested requestAnimationFrame ticks before the first size-dependent build so clientWidth / clientHeight are not zero.
• On cleanup, cancel rAF, disconnect ResizeObserver, remove listeners, dispose textures/geometries/materials/renderer, and clear the scene.

Files To Read

• Read FULL_BLEED_CANVAS.md (this folder) for edge-to-edge layout, readDrawableCssSize, setSize(..., false), resize observers, and anti-pillarboxing rules—read this before changing sizing or CSS.
• Read reference.md for shader contracts, sizing, layers, and performance rules.
• Read examples/MonochromeDotsBackground.tsx for a complete background-only component: full-bleed wrapper + canvas, readDrawableCssSize, orthographic camera, setSize(..., false), ResizeObserver + window + visualViewport, optional document.body portal, and prop-driven customization.
• Optional: examples/particle-config.example.json — copy into your app as e.g. src/particle-config.json and import as documented in Optional JSON in this file and in reference.md.

The repository root also has FULL_VIEWPORT_PARTICLE_BACKGROUND.md (extra ortho/parity notes). FULL_BLEED_CANVAS.md is duplicated in this skill folder so vendoring only skills/monochrome-particle/ still includes the full-bleed guide.

Integration

• Mount the component once near the app root. Ensure #root (or your app shell) is full width or sits above the background with position: relative; z-index: 1+ so a narrow max-width on #root does not crop the wrapper if the background stays in-tree.
• Default: keep the background in the React tree (no portal) for predictable refs and Vite/CSR dev; opt in to createPortal(..., document.body) only when #root is narrow or fixed stacking is unreliable.
• The example uses an inline-style full-bleed wrapper (100dvw / 100dvh, fixed, inset: 0) and an absolutely inset canvas at 100%×100%.
• Avoid negative z-index on the wrapper unless the stacking context is controlled; otherwise the body background can hide WebGL.
• Wire resize to window, visualViewport (if defined), and ResizeObserver on the canvas, wrapper, and optionally document.documentElement; coalesce with requestAnimationFrame.
• Keep the component independent from routes, buttons, and page transitions.

Verification

• Changing colors, speed, direction, density, pointSize, opacity, or zoom produces the expected visual change.
• Resize, rotation, mobile browser chrome show/hide, and tab hide/show work without console errors; no black pillarboxing when the painted area is wider than a lagging innerWidth.
• Unmounting disposes textures, geometries, materials, and renderer resources.
• React StrictMode double-mounting in development can surface fragile WebGL init; prefer idempotent setup/teardown (or disable StrictMode locally while debugging-only if needed).
• No references to sandstorm, route transitions, or CTA-triggered navigation are introduced.