@kitware/vtk.js/Filters/General/ContourLoopExtraction.js

Visualization Toolkit for the Web

import { m as macro } from '../../macros2.js';
import vtkPolyData from '../../Common/DataModel/PolyData.js';

const Dir = {
  Forward: 1,
  Backward: -1
};
const visited = new Set();
function vtkContourLoopExtraction(publicAPI, model) {
  publicAPI.requestData = (inData, outData) => {
    const [input] = inData;
    const output = outData[0]?.initialize() || vtkPolyData.newInstance();
    outData[0] = output;
    publicAPI.extractContours(input, output);
    output.modified();
  };
  publicAPI.traverseLoop = (pd, dir, startLineId, startPtId, loopPoints) => {
    let lineId = startLineId;
    let lastPtId = startPtId;
    let terminated = false;
    let numInserted = 0;
    while (!terminated) {
      const {
        cellPointIds
      } = pd.getCellPoints(lineId);
      if (!cellPointIds) {
        // eslint-disable-next-line no-continue
        continue;
      }
      lastPtId = cellPointIds[0] !== lastPtId ? cellPointIds[0] : cellPointIds[1];
      numInserted++;

      // parametric point value
      const t = dir * numInserted;
      loopPoints.push({
        t,
        ptId: lastPtId
      });
      const lineCell = pd.getPointCells(lastPtId);
      if (lineCell.length !== 2 || lastPtId === startPtId) {
        // looped
        return lastPtId;
      }
      if (lineCell.length === 2) {
        // continue along loop
        lineId = lineCell[0] !== lineId ? lineCell[0] : lineCell[1];
        visited.add(lineId);
      } else {
        // empty or invalid cell
        terminated = true;
      }
    }
    return lastPtId;
  };
  publicAPI.extractContours = (input, output) => {
    const loops = [];
    visited.clear();
    const inLines = input.getLines();
    output.getPoints().setData(Float32Array.from(input.getPoints().getData()));

    // TODO skip if cached input mtime hasn't changed.
    // iterate over input lines
    for (let li = 0; li < inLines.getNumberOfCells(); li++) {
      if (visited.has(li)) {
        // eslint-disable-next-line no-continue
        continue;
      }
      const {
        cellPointIds
      } = input.getCellPoints(li);
      if (!cellPointIds) {
        // eslint-disable-next-line no-continue
        continue;
      }
      visited.add(li);
      const startPtId = cellPointIds[0];
      const loopPoints = [];
      loopPoints.push({
        t: 0,
        ptId: startPtId
      });
      const endPtId = publicAPI.traverseLoop(input, Dir.Forward, li, startPtId, loopPoints);
      if (startPtId !== endPtId) {
        // didn't find a loop. Go other direction to see where we end up
        publicAPI.traverseLoop(input, Dir.Backward, li, startPtId, loopPoints);
        loopPoints.sort((a, b) => a.t < b.t ? -1 : 1);
        // make closed contour
        if (loopPoints.length && loopPoints[0].ptId !== loopPoints[loopPoints.length - 1]?.ptId) {
          loopPoints.push({
            ...loopPoints[loopPoints.length - 1]
          });
        }
      }
      if (loopPoints.length) {
        loops.push(loopPoints);
      }
    }

    // clear output lines
    const outLines = output.getLines();
    outLines.resize(0);
    loops.forEach(loop => {
      outLines.insertNextCell(loop.map(pt => pt.ptId));
    });
  };
}

// ----------------------------------------------------------------------------
// Object factory
// ----------------------------------------------------------------------------

const DEFAULT_VALUES = {};

// ----------------------------------------------------------------------------

function extend(publicAPI, model, initialValues = {}) {
  Object.assign(model, DEFAULT_VALUES, initialValues);
  macro.obj(publicAPI, model);
  macro.algo(publicAPI, model, 1, 1);
  vtkContourLoopExtraction(publicAPI);
}

// ----------------------------------------------------------------------------

const newInstance = macro.newInstance(extend, 'vtkContourLoopExtraction');

// ----------------------------------------------------------------------------

var index = {
  newInstance,
  extend
};

export { index as default, extend, newInstance };