jsketcher/web/app/cad/sketch/sketchBoundaries.js

import {areEqual, circleFromPoints, distanceAB, radiusOfCurvature, TOLERANCE} from '../../math/math';
import * as vec from '../../math/vec';
import {iteratePath} from '../cad-utils';
import NurbsCurve from '../../brep/geom/curves/nurbsCurve';
import {veqXYZ} from '../../brep/geom/tolerance';
import curveTess, {curveTessParams} from '../../brep/geom/impl/curve/curve-tess';

export function getSketchBoundaries(sceneFace) {
  const boundary = {lines: [], arcs: [], circles: [], nurbses: []};
  let w2sTr = sceneFace.worldToSketchTransformation;
  let _w2sTrArr = null;
  let w2sTrArr = () => _w2sTrArr || (_w2sTrArr = w2sTr.toArray()); 
  if (!sceneFace.brepFace) {
    return boundary;
  }
  for (let he of sceneFace.brepFace.edges) {
    let curve = he.edge.curve.impl;
    if (curve.constructor.name === 'NurbsCurve' && curve.degree() !== 1) {
      let curve2d = curve.transform(w2sTrArr());
      let arcRadius = findArcRadius(curve2d);
      if (arcRadius !== null){
        let [from, to] = curve2d.domain();
        let [A, DA, DDA] = curve2d.eval(from, 2);
        let [B, DB] = curve2d.eval(to, 1);

        let mA = vec.normalize(DA);
        let mmA = vec.normalize(DDA);

        let orient = mA[0] * mmA[1] - mA[1] * mmA[0];
        
        if (orient < 0) {
          let t;
          
          t = B;
          B = A;
          A = t;
          
          t = DB;
          DB = DA;
          DA = t;
          
          mA = vec.normalize(DA);
        }
        
        if (veqXYZ(A[0], A[1], 0, B[0], B[1], 0)) {
          let centripetal = perpXY(vec.mul(mA, arcRadius));
          let c = vec._add(centripetal, A);
          boundary.circles.push({
            c: {x: c[0], y: c[1]},
            r: arcRadius
          });
          continue;
        }
        
        let centripetalB = vec.normalize(DB);
        perpXY(centripetalB);

        let proj = vec.dot(mA, vec.sub(A, B));
        let u = proj / vec.dot(mA, centripetalB);

        let C = vec._add(vec._mul(centripetalB, u), B);
        boundary.arcs.push({
          a: {x: A[0], y: A[1]},
          b: {x: B[0], y: B[1]},
          c: {x: C[0], y: C[1]}
        });
      } else {
        boundary.nurbses.push(curve.transform(w2sTrArr()).serialize())
      }
    } else {
      addSegment(w2sTr.apply(he.vertexA.point), w2sTr.apply(he.vertexB.point));
    }
  }
  return boundary;


  function sameSketchObject(a, b) {
    if (a.sketchConnectionObject === undefined || b.sketchConnectionObject === undefined) {
      return false;
    }
    return a.sketchConnectionObject.id === b.sketchConnectionObject.id;
  }

  let paths = sceneFace.getBounds();

  //sceneFace.polygon.collectPaths(paths);

  function addSegment(a, b) {
    boundary.lines.push({
      a: {x: a.x, y: a.y},
      b: {x: b.x, y: b.y}
    });
  }

  let dist = distanceAB;

  function addArc(arc) {
    function addArcAsSegments(arc) {
      for (let i = 1; i < arc.length; i++) {
        addSegment(arc[i - 1], arc[i]);
      }
    }

    if (arc.length < 5) {
      addArcAsSegments(arc);
      return;
    }
    let a = arc[1], b = arc[arc.length - 2];

    let mid = (arc.length / 2) >> 0;
    let c = circleFromPoints(a, arc[mid], b);
    if (c === null) {
      addArcAsSegments(arc);
      return;
    }

    let rad = dist(a, c);

    if (Math.abs(rad - dist(b, c)) > TOLERANCE) {
      addArcAsSegments(arc);
      return;
    }

    let firstPoint = arc[0];
    let lastPoint = arc[arc.length - 1];
    if (Math.abs(rad - dist(firstPoint, c)) < TOLERANCE) {
      a = firstPoint;
    } else {
      addSegment(firstPoint, a);
    }

    if (Math.abs(rad - dist(lastPoint, c)) < TOLERANCE) {
      b = lastPoint;
    } else {
      addSegment(b, lastPoint);
    }

    if (!cad_utils.isCCW([a, arc[mid], b])) {
      let t = a;
      a = b;
      b = t;
    }
    boundary.arcs.push({
      a: {x: a.x, y: a.y},
      b: {x: b.x, y: b.y},
      c: {x: c.x, y: c.y}
    });
  }

  function addCircle(circle) {
    let n = circle.length;
    //let c = math.circleFromPoints(circle[0], circle[((n / 3) >> 0) % n], circle[((2 * n / 3) >> 0) % n]);
    let c = circleFromPoints(circle[0], circle[1], circle[2]);
    if (c === null) return;
    let r = dist(circle[0], c);
    boundary.circles.push({
      c: {x: c.x, y: c.y},
      r: r
    });
  }

  function isCircle(path) {
    for (let i = 0; i < path.length; i++) {
      let p = path[i];
      if (p.sketchConnectionObject === undefined
        || p.sketchConnectionObject._class !== 'TCAD.TWO.Circle'
        || p.sketchConnectionObject.id !== path[0].sketchConnectionObject.id) {
        return false;
      }
    }
    return true;
  }

  function trPath(path) {
    let out = [];
    for (let i = 0; i < path.length; i++) {
      out.push(w2sTr.apply(path[i]));
    }
    return out;
  }

  for (let i = 0; i < paths.length; i++) {
    let path = paths[i];
    if (path.length < 3) continue;
    let shift = 0;
    if (isCircle(path)) {
      addCircle(trPath(path));
      continue;
    }
    iteratePath(path, 0, function (a, b, ai, bi) {
      shift = bi;
      return sameSketchObject(a, b);
    });
    let currSko = null;
    let arc = null;
    iteratePath(path, shift + 1, function (a, b, ai, bi, iterNumber, path) {
      let isArc = a.sketchConnectionObject !== undefined &&
        (a.sketchConnectionObject._class === 'TCAD.TWO.Arc' || a.sketchConnectionObject._class === 'TCAD.TWO.Circle'); //if circle gets splitted
      let a2d = w2sTr.apply(a);
      if (isArc) {
        if (currSko !== a.sketchConnectionObject.id) {
          currSko = a.sketchConnectionObject.id;
          if (arc !== null) {
            arc.push(a2d);
            addArc(arc);
          }
          arc = [];
        }
        arc.push(a2d);
        if (iterNumber === path.length - 1) {
          arc.push(w2sTr.apply(b));
          addArc(arc);
        }
      } else {
        if (arc !== null) {
          arc.push(a2d);
          addArc(arc);
          arc = null;
        }
        currSko = null;
        addSegment(a2d, w2sTr.apply(b));
      }
      return true;
    });
  }
  return boundary;
}

function findArcRadius(curve) {
  if (curve.degree() !== 2) {
    return null;
  }
  let [uMin, uMax] = curve.domain();
  let knots = curveTessParams(curve, uMin, uMax);
  let prevRadCur = null;
  for (let knot of knots) {
    let [P, D, DD] = curve.eval(knot, 2);
    let radCur = radiusOfCurvature(D, DD);
    if (prevRadCur !== null && !areEqual(radCur, prevRadCur, 0.1)) {
      return null;
    }
    prevRadCur = radCur;
  }
  return prevRadCur;
}

function perpXY(v) {
  let [x, y] = v;

  v[0] = - y;
  v[1] =   x;
  return v;
}