Function createHaloGradationFromHSL

HSLから輪っかグラデーション作成 mock: https://runstant.com/pentamania/projects/ed04e522

Example

const params = [64, 32, 120]; // [rad, haloWidth, hue]
const grad = createHaloGradationFromHSL.call(ctx, ...params);
ctx.fillStyle = grad;