Clyune Component GalleryTwin Metaballs · How it works & code
Every ball produces 1/d In the field, the sum of the field is greater than the threshold, even if it is "the inner sphere of the sphere", so the borders are smoothly linked when the ball approaches.
Runtime logic
Visiting `/webgl/metaball`, DemoHost lazy-loads `demos/kits/kit-webgl.js` (registry `mod: 'kit-webgl'`) and calls `mount(host, { variant: 'metaball' })`. mount resolves the variant to family `metaball`; `withControls` builds the control panel (6 presets + sliders). `createCanvasStage` creates the `<canvas>` (HiDPI ≤ 2×, ResizeObserver) and the info panel. `makeGL` compiles this demo’s GLSL fragment shader on an offscreen WebGL canvas; each frame sets uniforms (u_t, u_m, u_col…), `drawArrays` renders a full-screen quad, then `drawImage` copies it onto the 2D stage. The family’s `build(S)` initialises state and returns the per-frame callback. Every `requestAnimationFrame`: read controls, advance a speed-scaled clock (dt ≤ 50 ms), run the frame callback; returned readouts go to the info panel. Changing parameters: colour/speed/size apply live; structural ones remount; leaving the page cancels rAF, removes listeners and frees resources.
Environment
Canvas 2D: 2D canvas drawing; WebGL 1: Offscreen WebGL canvas running a GLSL fragment shader; requestAnimationFrame: Display-synced animation loop; ResizeObserver: Canvas follows container size; Pointer Events: Unified mouse/touch/pen events; devicePixelRatio: Crisp HiDPI rendering (capped at 2×) · react 18.3.1, react-router-dom 6.30.6, vite 5.4.21
Dependencies
react 18.3.1
Imported APIs
withControls — Wraps the demo in the shared control panel (presets, sliders, reset); hot-updates or remounts on change; paramsFromSpec — Turns the spec (colour/speed/size/count/extras) into control-panel parameter definitions; createCanvasStage — Shared Canvas 2D stage: canvas + info panel, HiDPI, one rAF loop, pointer state, idle auto-pointer; hexRgb — Colour string → [r, g, b]; clamp — Clamps a value to a range; fmt — Number formatting (fixed decimals); F — Formula block HTML; S.clear — Clears with the background colour (translucent = trails); S.onFrame — Registers a per-frame callback; its return value feeds the info panel; ctx.fillText() — Draws filled text; ctx.beginPath() — Starts a new path; ctx.moveTo() — Moves the pen without drawing; ctx.arcTo() — Adds an arc using tangent lines; ctx.closePath() — Closes the current sub-path; ctx.fill() — Fills the current path; ctx.stroke() — Strokes the current path; ctx.drawImage() — Draws an image or offscreen canvas; ctx.fillRect() — Fills a rectangle; gl.createShader() — Creates a vertex/fragment shader; gl.shaderSource() — Sets shader source; gl.compileShader() — Compiles a GLSL shader; gl.getShaderParameter() — Queries shader compile status; gl.getShaderInfoLog() — Reads the shader compile log; gl.createProgram() — Creates a shader program
Source code
frontend/src/demos/kits/kit-webgl.js: FAM.metaball (L232-L236)
Code walkthrough
L232-236: Calls the factory `glFam()` to produce the full definition (spec + doc + build) from the options below. L232-232: Title shown in the info and control panels: “Metaball Blending”. L232-232: Range/default of the size slider: Fusion Threshold. L232-232: Range/default of the count slider: Number of Balls. L233-233: Extra demo-specific slider/toggle: Outline Only. L233-233: Preset buttons: name → parameter overrides (4). L234-234: Body of the “Notes” section. L234-234: Main formula of the “Formula” section. L234-234: Second formula line. L235-236: GLSL fragment shader source (runs once per pixel on the GPU); uses uniforms `u_n`, `u_s`, `u_x`, `u_col`.
Principles
f = Σ 0.15 / |p − cᵢ| Internal = f > threshold Metaball: Technical 1 per ball / d The sum of the field is greater than the threshold, even if it is "within the sphere", so the boundary is smoothly linked when the ball approaches. The last ball follows the pointer. Every pixel is here GPU Nowadays run the same snigger independently (fragment shader), Enter pixel coordinates uv And time t, Output the color of this pixel.