@bluemath/topo/lib/topology.js

Topology module of BlueMath

"use strict";
/*

Copyright (C) 2017 Jayesh Salvi, Blue Math Software Inc.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

*/
/*
import {NDArray,div,arr,length} from '@bluemath/common'
import {Vertex} from './vertex'
import {Face} from './face'
import {HalfEdge} from './halfedge'

interface Trapezoid {
  top : HalfEdge;
  bottom : HalfEdge;
  leftp : Vertex;
  rightp : Vertex;
  adjascent : Trapezoid[];
}


export class Topology {

  vertices : Vertex[];
  faces : Face[];
  halfedges : HalfEdge[];

  constructor() {
    this.vertices = [];
    this.faces = [];
    this.halfedges = [];
  }

  fromPolygon(points:NDArray) {
    if(points.shape.length !== 2 || // Not a array of points
      (points.shape[1] !== 2 && points.shape[1] !== 3) // neither 2D nor 3D
    )
    {
      throw new Error("Expecting array of 2D or 3D points");
    }
    let firstVtx:Vertex|undefined = undefined;
    let prevHE:HalfEdge|undefined = undefined;
    let firstHEForward:HalfEdge|undefined = undefined;
    let firstHEBackward:HalfEdge|undefined = undefined;
    let curVtx:Vertex;
    for(let i=0; i<points.length; i++) {
      let point = <NDArray>points.get(i);
      curVtx = new Vertex(point);
      let heForward = new HalfEdge(curVtx);
      let heBackward = new HalfEdge(curVtx);
      if(!firstVtx) {
        firstVtx = curVtx;
        firstHEForward = heForward;
        firstHEBackward = heBackward;
      }
      curVtx.halfedge = heForward;
      if(prevHE) {
        prevHE.next = heForward;
        prevHE.prev = heBackward;
        heBackward.prev = prevHE;
      }
      this.vertices.push(curVtx);
      this.halfedges.push(heForward);
      this.halfedges.push(heBackward);
      prevHE = heForward;
    }
    // Add last HalfEdge pair that closes the polygon face
    curVtx!.halfedge!.next = firstHEForward;
    firstHEBackward!.prev = curVtx!.halfedge;
    prevHE!.prev = firstHEBackward;

    let face = new Face(this.halfedges[0]);
    this.faces.push(face);

  }

  createNewVertex(coord:number[]) {
    let v = new Vertex(arr(coord));
    this.vertices.push(v);
  }

  findVertexAt(coord:number[]):Vertex|null {
    let icoord = arr(coord);
    for(let v of this.vertices) {
      if(v.coord.isEqual(icoord)) {
        return v;
      }
    }
    return null;
  }

  generateTrapezoidMap() {

  }

  toSVG() {
    const VERTEX_RADIUS = 10;
    const HE_ORIGIN_RADIUS = 5;
    const WIDTH = 800;
    const HEIGHT = 800;
    const HE_OFFSET_LAT = 5;
    const HE_OFFSET_LON = 20;
    const HALFEDGE_STYLE = 'stroke:#000'
    const VTX_STYLE = 'fill:#44f'
    const HE_ORIGIN_STYLE = 'fill:#f44';

    let vtxmarkup = this.vertices.map(vtx => {
      let cx = vtx.coord!.get(0);
      let cy = HEIGHT-<number>vtx.coord!.get(1);
      let title = vtx.coord!.toString();
      return `<circle cx=${cx} cy=${cy} r=${VERTEX_RADIUS} `+
        `style="${VTX_STYLE}"><title>${title}</title></circle>`;
    }).join('\n');

    let hemarkup = this.halfedges.map(he => {
      let ocx,ocy,dcx,dcy;
      if(he.vertex) {
        ocx = <number>he.vertex.coord!.get(0);
        ocy = HEIGHT - <number>he.vertex.coord!.get(1);
      } else {
        ocx = 0.2 * WIDTH;
        ocy = HEIGHT - 0.2 * HEIGHT;
      }
      // TODO : prev needs to change
      if(he.prev && he.prev.vertex) {
        dcx = <number>he.prev.vertex.coord!.get(0);
        dcy = HEIGHT - <number>he.prev.vertex.coord!.get(1);
      } else {
        dcx = 0.8 * WIDTH;
        dcy = HEIGHT - 0.8 * HEIGHT;
      }
      let vec = arr([dcx-ocx,dcy-ocy]);
      let veclen = length(vec);
      let dir = (<NDArray>div(vec,veclen)).data;
      let ortho = [-dir[1],dir[0]];
      ocx += ortho[0] * HE_OFFSET_LAT + dir[0] * HE_OFFSET_LON;
      ocy += ortho[1] * HE_OFFSET_LAT + dir[1] * HE_OFFSET_LON;
      dcx += ortho[0] * HE_OFFSET_LAT - dir[0] * HE_OFFSET_LON;
      dcy += ortho[1] * HE_OFFSET_LAT - dir[1] * HE_OFFSET_LON;
      return `<line x1=${ocx} y1=${ocy} x2=${dcx} y2=${dcy} `+
        `style="${HALFEDGE_STYLE}"></line>`+
        `<circle cx=${ocx} cy=${ocy} r=${HE_ORIGIN_RADIUS} `+
        `style="${HE_ORIGIN_STYLE}"></circle>`;
    }).join('\n');

    return `
    <svg width=${WIDTH} height=${HEIGHT}>
      <g id="vertices">
      ${vtxmarkup}
      </g>
      <g id="halfedges">
      ${hemarkup}
      </g>
    </svg>
    `;
  }

}
*/