react-planner/src/utils/graph-inner-cycles.js

react-planner is a React Component for plans design. Draw a 2D floorplan and navigate it in 3D mode.

import Graph from './graph';
import getEdgesOfSubgraphs from './get-edges-of-subgraphs';
import graphCycles from './graph-cycles';
import {List} from 'immutable';

export function calculateInnerCycles(verticesArray, edgesArray) {
  let innerCycles = new List();

  let graph = new Graph(verticesArray.length);
  edgesArray.forEach(line => {
    graph.addEdge(line[0], line[1]);
    graph.addEdge(line[1], line[0]);
  });

  graph.BCC();

  let subgraphs = graph.subgraphs.filter(subgraph => subgraph.length >= 3);
  let edgesOfSubgraphsArray = getEdgesOfSubgraphs(subgraphs, graph);

  let edges = [];
  edgesOfSubgraphsArray.forEach(es => {
    es.forEach(edge => edges.push(edge))
  });

  let cycles = graphCycles(verticesArray, edges);
  cycles.v_cycles.forEach(cycle => {
    cycle.shift();
    innerCycles = innerCycles.push(cycle);
  });

  return innerCycles;
}

export function isClockWiseOrder(innerCycleWithCoords) {
  // See: https://stackoverflow.com/a/1165943 and http://blog.element84.com/polygon-winding.html

  let i = 0;
  let twiceEnclosedArea = 0;
  let size = innerCycleWithCoords.size;

  for (i = 0; i < size; i++) {

    let { x: x1, y: y1 } = innerCycleWithCoords.get(i);
    let { x: x2, y: y2 } = innerCycleWithCoords.get((i + 1) % size);

    twiceEnclosedArea += (x2 - x1) * (y2 + y1);
  }

  return twiceEnclosedArea > 0;
}