X-GIS
Examples
generic julia.ts

Julia set

Escape-time Julia fractal — z ← z² + c iterated per pixel, coloured by iteration count through a cosine palette. The constant c orbits on autopilot; move the pointer over the canvas to steer it by hand.

Live
Pointer-interactive
0.0s

One source, compiled every way

The DSL source below, compiled to WebGPU (WGSL), WebGL2 (GLSL ES 3.00 — two stages), and a reflection JSON the host binds from. Nothing but the DSL tab is hand-written. 

// ═══ @xgis/shader-dsl example — animated Julia set (escape-time fractal) ═══
//
// Iterate z ← z² + c per pixel until |z| escapes, then colour by the (smoothed)
// iteration count through a cosine palette. `c` orbits slowly so the fractal morphs.
// Showcases the DSL's `Loop` + early `Break` + a mutable `var` accumulator, typed
// ioStruct fn-params, and scalar×vector broadcast (the palette), all emitted to
// both WGSL (WebGPU) and GLSL ES 3.00 (WebGL2).


import {
  fn,
  module,
  u32,
  f32,
  vec2,
  vec3,
  vec4,
  sin,
  cos,
  dot,
  mix,
  Loop,
  If,
  Break,
  Var,
  Let,
  f32T,
  vec4fT,
} from '../src/index.ts'
import { VsOut, vs, fullscreenUniforms } from './_fullscreen.ts'
import type { ShaderExample } from './_shared.ts'
const U = fullscreenUniforms({ zoom: f32T, mouse: vec4fT })


// Iridescent cosine palette: 0.5 + 0.5·cos(2π(t + phase)).
const palette = fn('palette', { t: f32T }, ({ t }) => {
  const ph = vec3(0.0, 0.33, 0.67)
  // scalar t broadcasts over the phase vector; cos() is component-wise.
  return vec3(0.5).add(cos(t.add(ph).mul(6.283)).mul(0.5))
})


const fs = fn(
  'fs',
  { vo: VsOut },
  ({ vo }) => {
    const uv = vo.uv
    // centre the plane, scale by the zoom uniform
    const z = Var(vec2(uv.x.mul(2).sub(1), uv.y.mul(2).sub(1)).mul(U.field.zoom))
    // the Julia constant: orbits on autopilot; once the pointer has entered
    // (m.w = 1) it maps to the pointer instead — sweep the cursor to morph the
    // set by hand. The pointer is normalised to c-space ≈ [−0.8, 0.8]².
    const m = U.field.mouse
    const res = U.field.resolution
    const orbit = vec2(
      cos(U.field.time.mul(0.31)).mul(0.39).sub(0.4),
      sin(U.field.time.mul(0.41)).mul(0.39),
    )
    const held = vec2(m.x.div(res.x).mul(2).sub(1).mul(0.8), m.y.div(res.y).mul(2).sub(1).mul(0.8))
    const c = Let(mix(orbit, held, m.w))
    const it = Var(f32(0))
    Loop(
      u32(0),
      (i) => i.lt(u32(96)),
      () => {
        If(dot(z, z).gt(4), () => {
          Break()
        }) // escaped
        z.assign(vec2(z.x.mul(z.x).sub(z.y.mul(z.y)).add(c.x), z.x.mul(z.y).mul(2).add(c.y)))
        it.assign(it.add(1))
      },
    )
    // outside points (never escaped) → black core; escaped → palette by iteration
    const col = palette({ t: it.div(96).add(U.field.time.mul(0.05)) })
    return vec4(col.mul(it.div(96)), 1)
  },
  { stage: 'fragment', retAttr: '@location(0)' },
)


// `palette` is called via its handle in `fs`, so module() collects it transitively — funcs lists only the entry points.
const juliaModule = module({
  structs: [U.struct, VsOut.decl],
  bindings: [U.binding],
  funcs: [vs, fs],
})


export const julia: ShaderExample = {
  id: 'julia',
  title: 'Julia set',
  blurb:
    'Escape-time Julia fractal — z ← z² + c iterated per pixel, coloured by iteration count through a cosine palette. The constant c orbits on autopilot; move the pointer over the canvas to steer it by hand.',
  category: 'generic',
  file: 'julia.ts',
  module: juliaModule,
  renderable: true,
  controls: {
    time: { kind: 'time' },
    resolution: { kind: 'resolution' },
    zoom: { kind: 'slider', label: 'Zoom', min: 0.4, max: 2.0, step: 0.05, value: 1.4 },
    mouse: { kind: 'mouse' },
  },
}

Run it locally: npx tsx examples/print.ts julia — prints the WGSL, GLSL, reflection. Source: GitHub.

New to the IR? See Concepts; the full authoring + emit surface is in the API reference.