@thi.ng/geom/api/bpatch.js

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

import { mixCubic } from "@thi.ng/vectors/mix-cubic";
import { __copyShape } from "../internal/copy.js";
import { __ensureNumVerts } from "../internal/pclike.js";
import { APC } from "./apc.js";
class BPatch extends APC {
  type = "bpatch";
  dim = 2;
  constructor(points, attribs) {
    super(points, attribs);
    __ensureNumVerts(this.points.length, 16);
  }
  copy() {
    return __copyShape(BPatch, this);
  }
  copyTransformed(fn) {
    return __copyShape(BPatch, this, fn(this.points));
  }
  withAttribs(attribs) {
    return new BPatch(this.points, attribs);
  }
  edges() {
    const p = this.points;
    return [
      [0, 1],
      [1, 2],
      [2, 3],
      [0, 4],
      [1, 5],
      [2, 6],
      [3, 7],
      [4, 5],
      [5, 6],
      [6, 7],
      [4, 8],
      [5, 9],
      [6, 10],
      [7, 11],
      [8, 9],
      [9, 10],
      [10, 11],
      [8, 12],
      [9, 13],
      [10, 14],
      [11, 15],
      [12, 13],
      [13, 14],
      [14, 15]
    ].map(([a, b]) => [p[a], p[b]]);
  }
  unmapPoint(uv, out) {
    const cp = this.points;
    const [u, v] = uv;
    return mixCubic(
      out || null,
      mixCubic([], cp[0], cp[4], cp[8], cp[12], v),
      mixCubic([], cp[1], cp[5], cp[9], cp[13], v),
      mixCubic([], cp[2], cp[6], cp[10], cp[14], v),
      mixCubic([], cp[3], cp[7], cp[11], cp[15], v),
      u
    );
  }
  toHiccup() {
    const attribs = this.attribs;
    const acc = ["g", { fill: "none", ...attribs }];
    if (attribs?.res) {
      const res = attribs.res - 1;
      const delta = 1 / res;
      for (let u = 0; u <= res; u++) {
        const col = [];
        const row = [];
        const uu = u * delta;
        for (let v = 0; v <= res; v++) {
          const p = [uu, v * delta];
          col.push(this.unmapPoint(p));
          row.push(this.unmapPoint([p[1], p[0]]));
        }
        acc.push(["polyline", {}, col]);
        acc.push(["polyline", {}, row]);
      }
    } else {
      this.edges().forEach((l) => acc.push(["line", {}, ...l]));
    }
    return acc;
  }
}
export {
  BPatch
};