Fire and Flow

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Animated fire and buoyant smoke flowing around shapes you can move, resize, and rotate.
Try it

Drag a shape, use its resize and rotation handles, then click empty space to deselect.
What to learn

Share a flow field between smoke particles and solid obstacles.
Manipulate solid shapes through decorative particles.
Integration boundaries

Flow sources drive velocity and heat independently of particle emission.
The obstacle source supplies packed committed geometry; particles are not rigid bodies.
This is a Pibbl Canvas example. Its mount owns its runtime resources; call its controller’s dispose method when removing it. The preview starts automatically unless reduced motion is enabled; Stop disposes the mount. Preserve the source’s logical canvas size and aspect ratio. Native HTML is not captured by Canvas filters.
Complete source

Host setup for this source: use a canvas with width 720 and height 480, compile with jsx: "react-jsx" and jsxImportSource: "@pibbl/core", import its default mount, and call const controller = mount(canvas) after attaching the canvas. Call controller.dispose() before removing it.
fire-and-flow.example.tsx

import {
  PhysicsWorld2D,
  pibblPhysicsWorld2D,
  physicsObstacles2D,
  kinematicBody2D,
  collider2D,
} from "@pibbl/core/physics/2d";
import {
  Group,
  Rectangle,
  Ellipse,
  Polygon,
  Text,
  pibbl,
  definePrimitive,
  useConst,
  useComputed,
  usePlayback,
  useSignal,
  useManipulation,
  ManipulationFrame,
  DragHandle,
  ResizeHandles,
  RotationHandle,
  type WritableSignal,
  type PibblManipulationBox,
  repeat,
  sequence,
  wait,
  marker,
  type PibblController,
} from "@pibbl/core";
import {
  Particles2D,
  defineParticleEffect2D,
  particleCurve,
  particleRange,
  useParticleSystem,
  useFlowField2D,
  useFlowSource2D,
  type PibblParticleEmitter2D,
} from "@pibbl/core/particles";

// Original procedural artwork; buffers live with this mounted example.
function smokeSprite(variant: number): OffscreenCanvas {
  const canvas = new OffscreenCanvas(96, 96);
  const context = canvas.getContext("2d")!;
  // Overlapping shaded lobes give each soft sprite internal volume, rather
  // than a single bright dot. Three silhouettes keep the plume irregular.
  for (let i = 0; i < 7; i++) {
    const angle = i * 2.4 + variant;
    const x = 48 + Math.cos(angle) * (10 + (i % 3) * 4),
      y = 48 + Math.sin(angle) * 13;
    const radius = 22 + ((i + variant) % 3) * 3;
    const body = context.createRadialGradient(x - 5, y - 7, 0, x, y, radius);
    body.addColorStop(0, "rgba(193,204,211,0.52)");
    body.addColorStop(0.28, "rgba(156,171,183,0.48)");
    body.addColorStop(0.6, "rgba(84,102,119,0.34)");
    body.addColorStop(0.82, "rgba(61,78,94,0.14)");
    body.addColorStop(1, "rgba(61,78,94,0)");
    context.fillStyle = body;
    context.fillRect(0, 0, 96, 96);
  }
  return canvas;
}

function createFlameSurface() {
  const canvas = new OffscreenCanvas(112, 160);
  const context = canvas.getContext("2d")!;
  const pixels = context.createImageData(canvas.width, canvas.height);
  const lattice = new Float32Array(4096);
  let seed = 7919;
  for (let i = 0; i < lattice.length; i++) {
    seed = (Math.imul(seed, 1664525) + 1013904223) >>> 0;
    lattice[i] = seed / 4294967296;
  }
  const noise = (x: number, y: number) => {
    const ix = Math.floor(x),
      iy = Math.floor(y);
    let fx = x - ix,
      fy = y - iy;
    fx = fx * fx * (3 - 2 * fx);
    fy = fy * fy * (3 - 2 * fy);
    const a = lattice[((iy & 63) << 6) | (ix & 63)];
    const b = lattice[((iy & 63) << 6) | ((ix + 1) & 63)];
    const c = lattice[(((iy + 1) & 63) << 6) | (ix & 63)];
    const d = lattice[(((iy + 1) & 63) << 6) | ((ix + 1) & 63)];
    return a + (b - a) * fx + (c - a + (a - b - c + d) * fx) * fy;
  };
  let lastTime = -1,
    lastIntensity = -1;
  return {
    canvas,
    update(time: number, intensity: number) {
      if (time === lastTime && intensity === lastIntensity)
        return;
      lastTime = time;
      lastIntensity = intensity;
      for (let y = 0; y < canvas.height; y++) {
        const height = 1 - y / (canvas.height - 1);
        for (let x = 0; x < canvas.width; x++) {
          const u = (x / (canvas.width - 1) - 0.5) * 2;
          // Height increases upward; subtract time so the noise rises with it.
          const lift = height * 5 - time * 2.4;
          const curl = noise(u * 2.4 + 8, lift * 0.65) - 0.5;
          const bent =
            u - curl * height * 0.75;
          const grain =
            noise(bent * 5 + 20, lift) * 0.62 +
            noise(bent * 11 + 40, lift * 1.8) * 0.26 +
            noise(bent * 23 + 30, lift * 3.5) * 0.12;
          const taper = 0.5 * Math.pow(1 - height, 0.65);
          const envelope = 1 - Math.abs(bent) / Math.max(0.025, taper);
          const density = Math.max(
            0,
            Math.min(
              1,
              (envelope * 0.65 + grain * 0.9 - height * 0.7 - 0.2) * 3.4,
            ),
          );
          const hot = Math.min(1, density * 0.76 + (1 - height) * 0.27);
          const offset = (y * canvas.width + x) * 4;
          pixels.data[offset] = 255;
          pixels.data[offset + 1] = Math.round(55 + 196 * hot * hot);
          pixels.data[offset + 2] = Math.round(8 + 170 * Math.pow(hot, 5));
          pixels.data[offset + 3] = Math.round(
            255 * density * Math.min(1, (1 - height) * 14),
          );
        }
      }
      context.putImageData(pixels, 0, 0);
    },
  };
}

// A small effect primitive, composed in normal Pibbl paint order. The shared Pibbl
// clock changes time; rendering reuses one raster, with no separate frame loop.
const Flame = definePrimitive<{
  surface: ReturnType<typeof createFlameSurface>;
  time: number;
  intensity: number;
  x: number;
  y: number;
  pointerEvents: "none";
}>((props, _style, context) => {
  props.surface.update(props.time, props.intensity);
  const height = 100 + props.intensity * 45;
  context.drawImage(
    props.surface.canvas,
    props.x - 66,
    props.y - height + 6,
    132,
    height,
  );
});

const clockProgram = repeat(sequence(wait(40), marker("emit")), {
  iterations: Infinity,
});

function Obstacle({
  id,
  kind,
  initial,
  selected,
}: {
  id: string;
  kind: "rectangle" | "ellipse" | "triangle";
  initial: PibblManipulationBox;
  selected: WritableSignal<string | null>;
}) {
  const box = useSignal(initial);
  const rotation = useSignal(0);
  const controller = useManipulation({
    box,
    rotation,
    move: { bounds: { left: 30, top: 92, width: 660, height: 338 } },
    resize: { minWidth: 36, minHeight: 30, maxWidth: 250, maxHeight: 200 },
    rotate: {},
    onStart: () => selected.set(id),
  });
  const position = useComputed(() => {
    const b = box.get(),
      angle = rotation.get(),
      c = Math.cos(angle),
      sn = Math.sin(angle);
    return [
      b.left + b.width / 2 - (c * b.width) / 2 + (sn * b.height) / 2,
      b.top + b.height / 2 - (sn * b.width) / 2 - (c * b.height) / 2,
    ] as const;
  });
  const angleDegrees = useComputed(() => (rotation.get() * 180) / Math.PI);
  const { width, height } = box.get();
  const active = selected.get() === id;
  const paint = {
    fill:
      kind === "ellipse"
        ? "#657e9b"
        : kind === "triangle"
          ? "#997254"
          : "#397b83",
    stroke: active ? "#f2d6a1" : "#b3c7c755",
    strokeWidth: active ? 2 : 1,
    cursor: "grab" as const,
  };
  const select = () => selected.set(id);
  return (
    <ManipulationFrame {...controller.frameProps}>
      <DragHandle controller={controller}>
        <Group
          physics={kinematicBody2D({
            collider: false,
            target: { position, rotationDegrees: angleDegrees },
          })}
        >
          {kind === "rectangle" ? (
            <Rectangle
              keyboardFocusable
              onPointerDown={select}
              physics={collider2D()}
              style={{
                width,
                height,
                fill: paint.fill,
                stroke: paint.stroke,
                strokeWidth: paint.strokeWidth,
                cursor: paint.cursor,
              }}
            />
          ) : kind === "ellipse" ? (
            <Ellipse
              keyboardFocusable
              onPointerDown={select}
              physics={collider2D()}
              style={{
                cx: width / 2,
                cy: height / 2,
                radiusX: width / 2,
                radiusY: height / 2,
                fill: paint.fill,
                stroke: paint.stroke,
                strokeWidth: paint.strokeWidth,
                cursor: paint.cursor,
              }}
            />
          ) : (
            <Polygon
              keyboardFocusable
              onPointerDown={select}
              physics={collider2D()}
              style={{
                coords: [
                  [width / 2, 0],
                  [width, height],
                  [0, height],
                ],
                fill: paint.fill,
                stroke: paint.stroke,
                strokeWidth: paint.strokeWidth,
                cursor: paint.cursor,
              }}
            />
          )}
        </Group>
      </DragHandle>
      {active && <ResizeHandles controller={controller} />}
      {active && (
        <RotationHandle
          controller={controller}
          style={{ arc: true, readout: true }}
        />
      )}
    </ManipulationFrame>
  );
}

function FireAndFlow() {
  const burning = useSignal(true);
  const intensity = useSignal(0.8);
  const origin = useSignal<readonly [number, number]>([360, 370]);
  const drag = useSignal<number | null>(null);
  const fuelGesture = useConst(() => ({ x: 0, y: 0, moved: false }));
  const selected = useSignal<string | null>(null);
  const obstacles = physicsObstacles2D(pibblPhysicsWorld2D());
  const flow = useFlowField2D({
    bounds: { width: 720, height: 480 },
    resolution: [96, 64],
    obstacles,
  });
  const force = useComputed(
    () => [0, -180 * intensity.get()] as const,
  );
  const heat = useComputed(() => 4 * intensity.get());
  useFlowSource2D(flow, {
    position: origin,
    radius: 40,
    acceleration: force,
    heat,
    enabled: burning,
  });
  const effects = useConst(() => {
    const smokeEmitter = (variant: number): PibblParticleEmitter2D => ({
      bounds: { min: [-720, -480], max: [720, 480] },
      name: `smoke${variant}`,
      capacity: 360,
      overflow: "recycle-oldest" as const,
      emission: [{ type: "manual" as const, count: 1 }],
      shape: {
        type: "line" as const,
        from: [-18, -30] as const,
        to: [18, -30] as const,
      },
      initial: {
        lifetimeMilliseconds: particleRange(6500, 9000),
        rotationDegrees: particleRange(0, 360),
      },
      appearance: {
        size: particleCurve([
          [0, 20 + variant * 3],
          [0.25, 44 + variant * 5],
          [1, 85 + variant * 8],
        ]),
        opacity: particleCurve([
          [0, 0],
          [0.08, 0.32],
          [0.6, 0.2],
          [1, 0],
        ]),
      },
      renderer: { type: "sprite" as const, source: smokeSprite(variant) },
    });
    return {
      smoke: defineParticleEffect2D({
        emitters: [smokeEmitter(0), smokeEmitter(1), smokeEmitter(2)],
      }),
      fire: defineParticleEffect2D({
        emitters: [
          {
            name: "embers",
            capacity: 80,
            overflow: "recycle-oldest",
            emission: [{ type: "manual", count: 1 }],
            shape: { type: "line", from: [-22, -10], to: [22, -10] },
            initial: {
              lifetimeMilliseconds: particleRange(1300, 2600),
              velocity: [particleRange(-30, 30), particleRange(-160, -90)],
              color: "#ffb85c",
              size: [2, 4],
            },
            motion: [{ type: "sway", amplitude: 8, frequency: [0.3, 0.8] }],
            appearance: {
              opacity: particleCurve([
                [0, 0],
                [0.1, 1],
                [0.55, 0.6],
                [1, 0],
              ]),
            },
            renderer: { type: "rectangle", blend: "additive" },
          },
        ],
      }),
    };
  });
  const smoke = useParticleSystem(effects.smoke, { flow, seed: 42 });
  const fire = useParticleSystem(effects.fire, { seed: 74 });
  const tick = useConst(() => ({ value: 0 }));
  const flameSurface = useConst(createFlameSurface);
  const flameTime = useSignal(0);
  usePlayback(clockProgram, {
    autoplay: true,
    onEvent: (event) => {
      if (event.type !== "marker") return;
      if (!burning.get()) return;
      const position = origin.get();
      flameTime.update((time) => time + 0.04);
      tick.value++;
      if (tick.value % 4 === 0) fire.emit("embers", { position });
      smoke.emit(`smoke${tick.value % 3}`, {
          position,
          count: Math.ceil(3 * intensity.get()),
        });
    },
  });
  const [x, y] = origin.get();
  return (
    <Group
      onKeyDown={(event) => {
        if (event.key === "Escape") selected.set(null);
      }}
    >
      <Rectangle
        onPointerDown={() => selected.set(null)}
        style={{ width: 720, height: 480, fill: "#111820" }}
      />
      <Rectangle
        pointerEvents="none"
        style={{
          left: 24,
          top: 80,
          width: 672,
          height: 360,
          fill: "#18232d",
          stroke: "#2d3b47",
        }}
      />
      <Text
        pointerEvents="none"
        style={{
          left: 32,
          top: 34,
          fill: "#f4e9d5",
          font: "700 24px sans-serif",
        }}
      >
        FIRE & FLOW
      </Text>
      <Text
        pointerEvents="none"
        style={{ left: 32, top: 59, fill: "#9eafbd", font: "13px sans-serif" }}
      >
        Drag a shape. Select to resize or rotate. Click empty space to deselect.
      </Text>
      <Rectangle
        onPointerDown={(e) => {
          e.currentTarget.setPointerCapture(e.pointerId);
          drag.set(e.pointerId);
          fuelGesture.x = e.x;
          fuelGesture.y = e.y;
          fuelGesture.moved = false;
        }}
        onPointerMove={(e) => {
          if (drag.get() === e.pointerId) {
            fuelGesture.moved ||=
              Math.hypot(e.x - fuelGesture.x, e.y - fuelGesture.y) > 3;
            if (fuelGesture.moved)
              origin.set([
                Math.max(90, Math.min(630, e.x)),
                Math.max(320, Math.min(395, e.y)),
              ]);
          }
        }}
        onPointerUp={(e) => {
          if (drag.get() === e.pointerId) {
            e.currentTarget.releasePointerCapture(e.pointerId);
            drag.set(null);
          }
        }}
        onPointerCancel={() => drag.set(null)}
        onClick={() => {
          if (!fuelGesture.moved) burning.update((v) => !v);
        }}
        style={{
          left: x - 40,
          top: y,
          width: 80,
          height: 54,
          fill: burning.get() ? "#954526" : "#4d5660",
          stroke: "#c78958",
          cursor: drag.get() === null ? "grab" : "grabbing",
        }}
      />
      <Particles2D
        system={smoke}
        pointerEvents="none"
        style={{ width: 720, height: 480 }}
      />
      {burning.get() && (
        <Flame
          surface={flameSurface}
          time={flameTime.get()}
          intensity={intensity.get()}
          x={x}
          y={y}
          pointerEvents="none"
        />
      )}
      <Particles2D
        system={fire}
        pointerEvents="none"
        style={{ width: 720, height: 480 }}
      />
      <Rectangle
        pointerEvents="none"
        style={{
          left: x - 45,
          top: y + 39,
          width: 90,
          height: 15,
          fill: "#39434b",
          stroke: "#76808a",
        }}
      />
      <Obstacle
        id="rectangle"
        kind="rectangle"
        initial={{ left: 285, top: 245, width: 100, height: 55 }}
        selected={selected}
      />
      <Obstacle
        id="ellipse"
        kind="ellipse"
        initial={{ left: 385, top: 145, width: 125, height: 65 }}
        selected={selected}
      />
      <Obstacle
        id="triangle"
        kind="triangle"
        initial={{ left: 190, top: 125, width: 90, height: 85 }}
        selected={selected}
      />
      <Rectangle
        onClick={() => intensity.update((v) => (v >= 1.2 ? 0.4 : v + 0.4))}
        style={{
          left: 32,
          top: 447,
          width: 180,
          height: 26,
          fill: "#2d3d49",
          cursor: "pointer",
        }}
      />
      <Text
        pointerEvents="none"
        style={{ left: 44, top: 465, fill: "#d5e1e8", font: "12px sans-serif" }}
      >
        Intensity {Math.round(intensity.get() * 100)}%
      </Text>
      <Rectangle
        onClick={() => selected.set(null)}
        style={{
          left: 226,
          top: 447,
          width: 462,
          height: 26,
          fill: "#2d3d49",
          cursor: "pointer",
        }}
      />
      <Text
        pointerEvents="none"
        style={{
          left: 239,
          top: 465,
          fill: "#d5e1e8",
          font: "12px sans-serif",
        }}
      >
        {selected.get() ? "Deselect shape" : "Select a shape"}
      </Text>
    </Group>
  );
}
export default function mount(canvas: HTMLCanvasElement): PibblController {
  return pibbl(
    canvas,
    <PhysicsWorld2D space="local" gravity={[0, 0]}>
      <FireAndFlow />
    </PhysicsWorld2D>,
    { pixelRatio: 1 },
  );
}
Documentation version

Documentation built with @pibbl/core 0.0.2, revision 272a94a. ALPHA — NOT FOR PRODUCTION USE.