Physics Confetti

Position from time alone

Nothing is stepped frame by frame. createConfettiParticles gives each shard a launch angle inside the spread cone, a speed between 50% and 130% of power and a spin rate. transformAt then works out position, rotation and fade from elapsed seconds, so a late frame can't knock a shard off its arc, and gravity, read every frame, can still bend a burst that is already in the air.

const angle = -Math.PI / 2 + (rand() - 0.5) * spread;const speed = power * (0.5 + rand() * 0.8);// …return {  x: p.vx * t,  y: p.vy * t + 0.5 * gravity * t * t,  rot: p.rot0 + p.rotV * t,  alpha: Math.max(0, 1 - t / 3),};

Spinning about the center

Each shard is an RSXform: scale times cosine, scale times sine, and a translation. Skia rotates a sprite about its top-left corner, so the worklet subtracts the rotated half-size and the shard spins about its middle. This draw passes no per-sprite colors, so the fade is folded into the scale, and a shard shrinks away over three seconds instead of turning transparent.

const tr = transformAt(particles[i], t, gravity);const s = particles[i].scale * tr.alpha;const cos = Math.cos(tr.rot) * s;const sin = Math.sin(tr.rot) * s;const half = SPRITE / 2;val.set(  cos,  sin,  originX + tr.x - (cos * half - sin * half),  originY + tr.y - (sin * half + cos * half),);

Replays and the clock

The seed is the fire count run through a multiplicative hash into mulberry32, so the same count always replays the same burst, and a new fire replaces shards still in flight. The frame clock runs for five seconds per burst and then lands, leaving a static picture. An always-running clock was measured at about 20% CPU while idle.

(fireSignal * 2654435761) % 1_000_000_007 || 1,// …scheduleOnUI(() => {  "worklet";  start.set(clock.get());});requestFrames(BURST_MS);

• Count150
• Power900
• Spread2.2
• Gravity1500