Flame jet

// Flame jet — 32x64 (the vent is a 32px floor piece; the canvas is tall so the fire column fits), top-down 3/4,// key light top-left. A ring of dressed stone blocks round a pit, an iron grate across the pit.// All fire colours are the fl0..3 family, so the whole jet (column, glow on the stone, embers) swaps with swap("fl", ...).// Variants (all 32x64, ground at the bottom so they align)://   idle        loop 8f  — the pit smoulders under the grate, a few embers climb and cool//   burst       loop 12f — a roaring column of fire rises well above the vent, tongues tear off the top//   burst-soul  loop 12f — the same in soulfire (fl -> soul)//   idle-soul   loop 8f  — the smouldering vent in soulfire, to pair with burst-soulconst CX = 16, GROUND = 61;const RING = { cy: 53, rx: 14.5, ry: 6, side: 2 };     // top face of the stone ring; `side` = height of its outer wallconst HOLE = { cy: 53, rx: 8.5, ry: 3.3 };             // opening in the ring's top faceconst GRATE = { cy: 54, rx: 8, ry: 2.9 };              // the grate sits a little below the top faceconst N_IDLE = 8, N_BURST = 12;const eR = (x, y, cx, cy, rx, ry) => { const nx = (x + 0.5 - cx) / rx, ny = (y + 0.5 - cy) / ry; return Math.sqrt(nx * nx + ny * ny); };const inE = (x, y, cx, cy, rx, ry) => eR(x, y, cx, cy, rx, ry) <= 1;const inRing = (x, y) => inE(x, y, CX, RING.cy, RING.rx, RING.ry);const inHole = (x, y) => inE(x, y, CX, HOLE.cy, HOLE.rx, HOLE.ry);// ---- stone ring ---------------------------------------------------------------------------------const BLOCKS = 8;function blockAt(x, y) {  // angle round the ring -> block index and position inside the block (0..1)  const a = Math.atan2((y + 0.5 - RING.cy) / RING.ry, (x + 0.5 - CX) / RING.rx);  const u = ((a / TAU) * BLOCKS + 0.5 + BLOCKS) % BLOCKS;  return [Math.floor(u), u - Math.floor(u)];}function ring(g, hot) {  const { cy, rx, ry, side } = RING;  g.part("ring", () => {    // outer wall (seen on the near half): lit on the left, turning away on the right, a dark foot on the floor    g.field({ x: [CX - rx - 1, CX + rx + 1], y: [cy, cy + ry + side + 1] }, (x, y) => {      if (inRing(x, y)) return null;      let d = 0;      for (let k = 1; k <= side; k++) if (inRing(x, y - k)) { d = k; break; }      if (!d) return null;      const [, f] = blockAt(x, y - d);      const nx = (x + 0.5 - CX) / rx;      if (f < 0.07 || f > 0.97) return "n0";                            // joint between blocks      if (d === 1) return nx < -0.45 ? "n3" : nx < 0.4 ? "n2" : "n1";      return nx < -0.45 ? "n1" : "n0";    });    // top face    g.field({ x: [CX - rx - 1, CX + rx + 1], y: [cy - ry - 1, cy + ry + 1] }, (x, y) => {      if (!inRing(x, y) || inHole(x, y)) return null;      const [k, f] = blockAt(x, y);      const r = eR(x, y, CX, cy, rx, ry), rh = eR(x, y, CX, HOLE.cy, HOLE.rx, HOLE.ry);      const nx = (x + 0.5 - CX) / rx, ny = (y + 0.5 - cy) / ry;      if (hot && rh < 1.16 && ny > -0.55) return "fl2";                 // the fire lights the inner lip      if (hot && rh < 1.36 && ny > 0.1) return "fl1";      if (f < 0.07 || f > 0.97) return "n1";                            // joint      if (r > 0.9) return nx + 0.6 * ny < 0.1 ? "n4" : "n3";           // outer arris      if (rh < 1.16) return ny > 0 ? "n4" : "n2";                       // inner arris: the near lip faces the light      return k === 2 || k === 5 ? "n2" : "n3";                          // two blocks sit a shade darker    });    // chips on a few blocks (countable marks)    for (const [x, y, c] of [[6, 50, "n2"], [25, 49, "n2"], [8, 57, "n2"], [24, 57, "n2"], [19, 58, "n2"]]) {      if (!hot || !inE(x, y, CX, HOLE.cy, HOLE.rx * 1.36, HOLE.ry * 1.36)) g.pixel(x, y, c);    }  });}// ---- pit & grate --------------------------------------------------------------------------------function pit(g, glow) {  g.part("pit", () => {    g.field({ x: [CX - HOLE.rx, CX + HOLE.rx], y: [HOLE.cy - HOLE.ry - 1, HOLE.cy + HOLE.ry + 1] }, (x, y) => {      if (!inHole(x, y)) return null;      if (!inE(x, y, CX, GRATE.cy, GRATE.rx, GRATE.ry)) return glow(-1, x, y);   // far inner wall      return glow(eR(x, y, CX, GRATE.cy, GRATE.rx * 0.85, GRATE.ry), x, y);    });  });}const isBar = (x, y) => y === GRATE.cy - 1 || y === GRATE.cy + 1 ? 2 : (x - CX + 30) % 3 === 0 ? 1 : 0;function grate(g, hot) {  // two bars across and short bars front-to-back, clipped to the grate's ellipse  g.part("grate", () => {    g.field({ x: [CX - GRATE.rx, CX + GRATE.rx], y: [GRATE.cy - GRATE.ry - 1, GRATE.cy + GRATE.ry + 1] }, (x, y) => {      if (!inE(x, y, CX, GRATE.cy, GRATE.rx, GRATE.ry)) return null;      const b = isBar(x, y);      if (!b) return null;      if (hot) return b === 2 && (x - CX + 30) % 3 !== 0 ? "n0" : "ink";   // silhouettes against the fire      if (b === 2) return (x - CX + 30) % 3 === 0 ? (x < CX + 2 ? "n3" : "n2") : x < CX - 2 ? "n2" : "n1";      return "n0";    });  });}// ---- fire ---------------------------------------------------------------------------------------// three flames rooted in the pit: a tall centre column and two short flankers leaning out. Each flame has nested// layers (shell, body, bright, core), each layer itself flame-shaped (shorter and narrower).const BASE = GRATE.cy + 1;const FLAMES = [  { name: "flankL", x: 11.5, h: 20, hw: 4.2, lean: -3.5, seed: 0.31 },  { name: "flankR", x: 20.5, h: 24, hw: 4.2, lean: 3.5, seed: 0.64 },  { name: "column", x: 16, h: 49, hw: 7.4, lean: 0, seed: 0.05 },];const LAYERS = [["fl0", 1, 1], ["fl1", 0.92, 0.72], ["fl2", 0.72, 0.48], ["fl3", 0.45, 0.25]];const profile = (k) => (k < 0.12 ? 0.82 + 0.18 * (k / 0.12) : k < 0.42 ? 1 - 0.14 * ((k - 0.12) / 0.3) : 0.86 * Math.pow((1 - k) / 0.58, 0.8));function flameH(f, t) {  return f.h * (1 + 0.07 * Math.sin(TAU * (2 * t + f.seed)) + 0.04 * Math.sin(TAU * (3 * t + 2 * f.seed)));}function flameAxis(f, t, k) {  return f.x + (f.lean + 1.5 * Math.sin(TAU * (t + f.seed))) * k * k + 1.1 * Math.sin(TAU * (1.3 * k - 2 * t + f.seed)) * k;}function layerOf(f, t, x, y) {  // index of the innermost layer of flame f covering pixel (x, y); -1 = outside  const k = (BASE + 1 - (y + 0.5)) / flameH(f, t);  if (k < 0 || k > 1) return -1;  const lick = 1 + 0.18 * Math.sin(TAU * (2.6 * k - 3 * t + 1.7 * f.seed)) + 0.07 * Math.sin(TAU * (5.2 * k - 2 * t));  const dx = Math.abs(x + 0.5 - flameAxis(f, t, k));  let li = -1;  for (let j = 0; j < LAYERS.length; j++) {    const [, hf, wf] = LAYERS[j], kj = k / hf;    if (kj > 1 || dx > f.hw * wf * profile(kj) * lick) break;    li = j;  }  return li;}function fire(g, t) {  // the flames merge: each pixel takes the hottest layer any flame puts there, so no shell cuts through a core  g.part("fire", () => g.field({ x: [0, 31], y: [0, BASE] }, (x, y) => {    if (y >= RING.cy && !inHole(x, y)) return null;          // the near half of the ring stands in front of the foot    let li = -1;    for (const f of FLAMES) li = Math.max(li, layerOf(f, t, x, y));    return li < 0 ? null : LAYERS[li][0];  }));}function tongues(g, t) {  // blobs tear off the tip of the column and rise, shrinking  const f = FLAMES[2];  g.detached("tongues", () => {    for (let i = 0; i < 2; i++) {      const p = (2 * t + i / 2) % 1;      const tip = BASE - flameH(f, t);      const x = Math.round(flameAxis(f, t, 1)) + (i ? 1 : -1);      const y = Math.round(tip - p * 8);      if (y < 1) continue;      if (p < 0.4) {        g.ellipse({ x: [x - 1, x + 1], y: [y - 2, y + 1] }, "fl0", { fill: "fl0" });        g.line([x, y - 1], [x, y], "fl1");      } else if (p < 0.7) { g.rect({ x: [x, x + 1], y: [y - 1, y] }, "fl0", { fill: "fl0" }); g.pixel(x, y, "fl1"); }      else if (p < 0.9) g.pixel(x, y, "fl0");    }  });}function embers(g, t, n, reach, y0, spread) {  g.detached("embers", () => {    for (let i = 0; i < n; i++) {      const p = (t + i / n) % 1, s = hash(i, 5) - 0.5;      const x = CX + Math.round(s * spread * (1 + p) + Math.sin(TAU * (p + hash(i, 2))) * 1.3);      const y = y0 - Math.round(p * reach * (0.75 + 0.25 * hash(i, 8)));      if (p < 0.85 && y >= 0) g.pixel(x, y, p < 0.25 ? "fl3" : p < 0.5 ? "fl2" : p < 0.7 ? "fl1" : "fl0");    }  });}// ---- sprite -------------------------------------------------------------------------------------const FlameJet = sprite(pal, (g, t, state) => {  const burst = state === "burst";  contactShadow(g, CX, GROUND, 16, 2);  g.outlined("ink", () => ring(g, burst));  if (!burst) {    // idle: the bed of embers under the grate breathes; a slow pulse travels across it    pit(g, (r, x, y) => {      const pulse = 0.5 + 0.5 * Math.sin(TAU * (t - x / 12));      if (r < 0) return (x + 0.5 - CX) / HOLE.rx > 0.35 ? "n1" : "n0";   // far inner wall      if (r < 0.35) return pulse > 0.7 ? "fl2" : "fl1";      if (r < 0.62) return pulse > 0.45 ? "fl1" : "fl0";      if (r < 0.88) return pulse > 0.6 ? "fl0" : "n0";      return "ink";    });    grate(g, false);    embers(g, t, 3, 11, GRATE.cy - 2, 8);    return;  }  pit(g, (r) => (r < 0 ? "fl1" : r < 0.6 ? "fl3" : "fl2"));  fire(g, t);  grate(g, true);  tongues(g, t);  embers(g, t, 8, 34, 46, 12);});submit(FlameJet, {  size: [32, 64], origin: "top-left", kind: "icon", scale: 1,  animate: { fps: 10, duration: N_IDLE / 10, loop: true },  anchor: { x: CX, y: GROUND },  variants: [    { name: "idle", args: ["idle"] },    { name: "burst", args: ["burst"], animate: { fps: 10, duration: N_BURST / 10, loop: true } },    { name: "burst-soul", args: ["burst"], animate: { fps: 10, duration: N_BURST / 10, loop: true }, repalette: swap("fl", "soul") },    { name: "idle-soul", args: ["idle"], repalette: swap("fl", "soul") },  ],});