@thi.ng/geom/point-at.js

Functional, polymorphic API for 2D geometry types & SVG generation

import { defmulti } from "@thi.ng/defmulti/defmulti";
import { Sampler } from "@thi.ng/geom-resample/sampler";
import { cossin } from "@thi.ng/math/angle";
import { TAU } from "@thi.ng/math/api";
import { fit01 } from "@thi.ng/math/fit";
import { cartesian2 } from "@thi.ng/vectors/cartesian";
import { madd2 } from "@thi.ng/vectors/madd";
import { mixCubic } from "@thi.ng/vectors/mix-cubic";
import { mixQuadratic } from "@thi.ng/vectors/mix-quadratic";
import { mixN2 } from "@thi.ng/vectors/mixn";
import { pointOnRay2, pointOnRay3 } from "@thi.ng/vectors/point-on-ray";
import { __dispatch } from "./internal/dispatch.js";
import { vertices } from "./vertices.js";
const pointAt = defmulti(
  __dispatch,
  {
    quad: "poly",
    tri: "poly"
  },
  {
    arc: ($, t) => $.pointAtTheta(fit01(t, $.start, $.end)),
    circle: ($, t) => cartesian2(null, [$.r, TAU * t], $.pos),
    cubic: ({ points }, t) => mixCubic([], points[0], points[1], points[2], points[3], t),
    ellipse: ($, t) => madd2([], cossin(TAU * t), $.r, $.pos),
    line: ({ points }, t) => mixN2([], points[0], points[1], t),
    poly: ($, t) => new Sampler($.points, true).pointAt(t),
    polyline: ($, t) => new Sampler($.points).pointAt(t),
    quadratic: ({ points }, t) => mixQuadratic([], points[0], points[1], points[2], t),
    ray: ($, t) => pointOnRay2([], $.pos, $.dir, t),
    ray3: ($, t) => pointOnRay3([], $.pos, $.dir, t),
    rect: ($, t) => new Sampler(vertices($), true).pointAt(t)
  }
);
export {
  pointAt
};