add spiral viz

packages/core/index.mjs

@@ -24,6 +24,7 @@ export * from './time.mjs';
 export * from './draw.mjs';
 export * from './animate.mjs';
 export * from './pianoroll.mjs';
+export * from './spiral.mjs';
 export * from './ui.mjs';
 export { default as drawLine } from './drawLine.mjs';
 export { default as gist } from './gist.js';

packages/core/spiral.mjs

@@ -0,0 +1,117 @@
+import { Pattern } from './index.mjs';
+
+// polar coords -> xy
+function fromPolar(angle, radius, cx, cy) {
+  const radians = ((angle - 90) * Math.PI) / 180;
+  return [cx + Math.cos(radians) * radius, cy + Math.sin(radians) * radius];
+}
+
+const xyOnSpiral = (angle, margin, cx, cy, rotate = 0) => fromPolar((angle + rotate) * 360, margin * angle, cx, cy); // TODO: logSpiral
+
+// draw spiral / segment of spiral
+function spiralSegment(options) {
+  let {
+    ctx,
+    from = 0,
+    to = 3,
+    margin = 50,
+    cx = 100,
+    cy = 100,
+    rotate = 0,
+    thickness = margin / 2,
+    color = '#0000ff30',
+    cap = 'round',
+    stretch = 1,
+    fromOpacity = 1,
+    toOpacity = 1,
+  } = options;
+  from *= stretch;
+  to *= stretch;
+  rotate *= stretch;
+  ctx.lineWidth = thickness;
+  ctx.lineCap = cap;
+  ctx.strokeStyle = color;
+  ctx.globalAlpha = fromOpacity;
+
+  ctx.beginPath();
+  let [sx, sy] = xyOnSpiral(from, margin, cx, cy, rotate);
+  ctx.moveTo(sx, sy);
+
+  const increment = 1 / 60;
+  let angle = from;
+  while (angle <= to) {
+    const [x, y] = xyOnSpiral(angle, margin, cx, cy, rotate);
+    //ctx.lineWidth = angle*thickness;
+    ctx.globalAlpha = ((angle - from) / (to - from)) * toOpacity;
+    ctx.lineTo(x, y);
+    angle += increment;
+  }
+  ctx.stroke();
+}
+
+Pattern.prototype.spiral = function (options = {}) {
+  const {
+    stretch = 1,
+    size = 80,
+    thickness = size / 2,
+    cap = 'butt', // round butt squar,
+    inset = 3, // start angl,
+    playheadColor = '#ffffff90',
+    playheadLength = 0.02,
+    playheadThickness = thickness,
+    padding = 0,
+    steady = 1,
+    inactiveColor = '#ffffff20',
+    colorizeInactive = 0,
+    fade = true,
+    // logSpiral = true,
+  } = options;
+
+  function spiral({ ctx, time, haps, drawTime }) {
+    ctx.clearRect(0, 0, ctx.canvas.clientWidth, ctx.canvas.clientHeight);
+    const [cx, cy] = [ctx.canvas.width / 2, ctx.canvas.height / 2];
+    const settings = {
+      margin: size / stretch,
+      cx,
+      cy,
+      stretch,
+      cap,
+      thickness,
+    };
+
+    const playhead = {
+      ...settings,
+      thickness: playheadThickness,
+      from: inset - playheadLength,
+      to: inset,
+      color: playheadColor,
+    };
+
+    const [min] = drawTime;
+    const rotate = steady * time;
+    haps.forEach((hap) => {
+      const isActive = hap.whole.begin <= time && hap.endClipped > time;
+      const from = hap.whole.begin - time + inset;
+      const to = hap.endClipped - time + inset - padding;
+      const { color } = hap.context;
+      const opacity = fade ? 1 - Math.abs((hap.whole.begin - time) / min) : 1;
+      spiralSegment({
+        ctx,
+        ...settings,
+        from,
+        to,
+        rotate,
+        color: colorizeInactive || isActive ? color : inactiveColor,
+        fromOpacity: opacity,
+        toOpacity: opacity,
+      });
+    });
+    spiralSegment({
+      ctx,
+      ...playhead,
+      rotate,
+    });
+  }
+
+  return this.onPaint((ctx, time, haps, drawTime) => spiral({ ctx, time, haps, drawTime }));
+};