CellPicker

Methods

computeSurfaceNormal

Argument	Type	Required	Description
data		Yes
cell	vtkCell	Yes
weights	Array.	Yes
normal	Array.	Yes

extend

Method use to decorate a given object (publicAPI+model) with vtkCellPicker characteristics.

Argument	Type	Required	Description
publicAPI		Yes	object on which methods will be bounds (public)
model		Yes	object on which data structure will be bounds (protected)
initialValues	ICellPickerInitialValues	No	(default: {})

getCellIJK

Get the structured coordinates of the cell at the PickPosition.

getCellIJKByReference

Get the structured coordinates of the cell at the PickPosition.

getCellId

Get the id of the picked cell.

getMapperNormal

getMapperNormalByReference

getOpacityThreshold

Get the opacity threshold for volume picking

getPCoords

Get the parametric coordinates of the picked cell.

getPCoordsByReference

initialize

newInstance

Method use to create a new instance of vtkCellPicker

Argument	Type	Required	Description
initialValues	ICellPickerInitialValues	No	for pre-setting some of its content

pick

Argument	Type	Required	Description
selection		Yes
renderer	vtkRenderer	Yes	The vtkRenderer instance.

setOpacityThreshold

Get the opacity threshold for volume picking

Source

index.d.ts

import vtkCell from '../../../Common/DataModel/Cell';
import { Vector3 } from '../../../types';
import vtkMapper from '../Mapper';
import vtkPicker, { IPickerInitialValues } from '../Picker';
import vtkProp3D from '../Prop3D';
import vtkRenderer from '../Renderer';
import { Nullable } from '../../../types';

/**
 *
 */
export interface ICellPickerInitialValues extends IPickerInitialValues {
  cellId?: number;
  pCoords?: Vector3;
  cellIJK?: number[];
  pickNormal?: number[];
  mapperNormal?: number[];
  opacityThreshold?: number;
}

export interface vtkCellPicker extends vtkPicker {
  /**
   * Get the structured coordinates of the cell at the PickPosition.
   */
  getCellIJK(): number[];

  /**
   * Get the structured coordinates of the cell at the PickPosition.
   */
  getCellIJKByReference(): number[];

  /**
   * Get the id of the picked cell.
   */
  getCellId(): number;

  /**
   *
   */
  getMapperNormal(): number[];

  /**
   *
   */
  getMapperNormalByReference(): number[];

  /**
   * Get the opacity threshold for volume picking
   */
  getOpacityThreshold(): number;

  /**
   * Get the opacity threshold for volume picking
   */
  setOpacityThreshold(value: number);

  /**
   * Get the parametric coordinates of the picked cell.
   */
  getPCoords(): number[];

  /**
   *
   */
  getPCoordsByReference(): number[];

  /**
   *
   */
  initialize(): void;

  /**
   *
   * @param data
   * @param {vtkCell} cell
   * @param {Number[]} weights
   * @param {Number[]} normal
   */
  computeSurfaceNormal(
    data: any,
    cell: vtkCell,
    weights: number[],
    normal: number[]
  ): boolean;

  /**
   *
   * @param selection
   * @param {vtkRenderer} renderer The vtkRenderer instance.
   */
  pick(selection: any, renderer: vtkRenderer): void;
}

/**
 * Method use to decorate a given object (publicAPI+model) with vtkCellPicker characteristics.
 *
 * @param publicAPI object on which methods will be bounds (public)
 * @param model object on which data structure will be bounds (protected)
 * @param {ICellPickerInitialValues} [initialValues] (default: {})
 */
export function extend(
  publicAPI: object,
  model: object,
  initialValues?: ICellPickerInitialValues
): void;

/**
 * Method use to create a new instance of vtkCellPicker
 * @param {ICellPickerInitialValues} [initialValues] for pre-setting some of its content
 */
export function newInstance(
  initialValues?: ICellPickerInitialValues
): vtkCellPicker;

export declare const vtkCellPicker: {
  newInstance: typeof newInstance;
  extend: typeof extend;
};
export default vtkCellPicker;

index.js

import macro from 'vtk.js/Sources/macros';
import vtkCellTypes from 'vtk.js/Sources/Common/DataModel/CellTypes';
import vtkLine from 'vtk.js/Sources/Common/DataModel/Line';
import vtkPicker from 'vtk.js/Sources/Rendering/Core/Picker';
import vtkPolyLine from 'vtk.js/Sources/Common/DataModel/PolyLine';
import vtkTriangle from 'vtk.js/Sources/Common/DataModel/Triangle';
import vtkQuad from 'vtk.js/Sources/Common/DataModel/Quad';
import * as vtkMath from 'vtk.js/Sources/Common/Core/Math';
import { CellType } from 'vtk.js/Sources/Common/DataModel/CellTypes/Constants';
import { vec3, vec4 } from 'gl-matrix';
import vtkBox from 'vtk.js/Sources/Common/DataModel/Box';

// ----------------------------------------------------------------------------
// Global methods
// ----------------------------------------------------------------------------

function createCellMap() {
  return {
    [CellType.VTK_LINE]: vtkLine.newInstance(),
    [CellType.VTK_POLY_LINE]: vtkPolyLine.newInstance(),
    [CellType.VTK_TRIANGLE]: vtkTriangle.newInstance(),
    [CellType.VTK_QUAD]: vtkQuad.newInstance(),
  };
}

function clipLineWithPlane(mapper, matrix, p1, p2) {
  const outObj = { planeId: -1, t1: 0.0, t2: 1.0, intersect: 0 };
  const nbClippingPlanes = mapper.getNumberOfClippingPlanes();
  const plane = [];
  for (let i = 0; i < nbClippingPlanes; i++) {
    mapper.getClippingPlaneInDataCoords(matrix, i, plane);

    const d1 =
      plane[0] * p1[0] + plane[1] * p1[1] + plane[2] * p1[2] + plane[3];
    const d2 =
      plane[0] * p2[0] + plane[1] * p2[1] + plane[2] * p2[2] + plane[3];

    // If both distances are negative, both points are outside
    if (d1 < 0 && d2 < 0) {
      return 0;
    }

    if (d1 < 0 || d2 < 0) {
      // If only one of the distances is negative, the line crosses the plane
      // Compute fractional distance "t" of the crossing between p1 & p2
      let t = 0.0;

      // The "if" here just avoids an expensive division when possible
      if (d1 !== 0) {
        // We will never have d1==d2 since they have different signs
        t = d1 / (d1 - d2);
      }

      // If point p1 was clipped, adjust t1
      if (d1 < 0) {
        if (t >= outObj.t1) {
          outObj.t1 = t;
          outObj.planeId = i;
        }
      } else if (t <= outObj.t2) {
        // else point p2 was clipped, so adjust t2
        outObj.t2 = t;
      }
      // If this happens, there's no line left
      if (outObj.t1 > outObj.t2) {
        outObj.intersect = 0;
        return outObj;
      }
    }
  }
  outObj.intersect = 1;
  return outObj;
}

// ----------------------------------------------------------------------------
// Static API
// ----------------------------------------------------------------------------

export const STATIC = {
  clipLineWithPlane,
};

// ----------------------------------------------------------------------------
// vtkCellPicker methods
// ----------------------------------------------------------------------------

function vtkCellPicker(publicAPI, model) {
  // Set our className
  model.classHierarchy.push('vtkCellPicker');

  const superClass = { ...publicAPI };

  function resetCellPickerInfo() {
    model.cellId = -1;

    model.pCoords[0] = 0.0;
    model.pCoords[1] = 0.0;
    model.pCoords[2] = 0.0;

    model.cellIJK[0] = 0.0;
    model.cellIJK[1] = 0.0;
    model.cellIJK[2] = 0.0;

    model.mapperNormal[0] = 0.0;
    model.mapperNormal[1] = 0.0;
    model.mapperNormal[2] = 1.0;

    model.pickNormal[0] = 0.0;
    model.pickNormal[1] = 0.0;
    model.pickNormal[2] = 1.0;
  }

  function resetPickInfo() {
    model.dataSet = null;
    model.mapper = null;
    resetCellPickerInfo();
  }

  publicAPI.initialize = () => {
    resetPickInfo();
    superClass.initialize();
  };

  publicAPI.computeSurfaceNormal = (data, cell, weights, normal) => {
    const normals = data.getPointData().getNormals();
    // TODO add getCellDimension on vtkCell
    const cellDimension = 0;
    if (normals) {
      normal[0] = 0.0;
      normal[1] = 0.0;
      normal[2] = 0.0;
      const pointNormal = [];
      for (let i = 0; i < 3; i++) {
        normals.getTuple(cell.getPointsIds()[i], pointNormal);
        normal[0] += pointNormal[0] * weights[i];
        normal[1] += pointNormal[1] * weights[i];
        normal[2] += pointNormal[2] * weights[i];
      }
      vtkMath.normalize(normal);
    } else if (cellDimension === 2) {
      // TODO
    } else {
      return 0;
    }
    return 1;
  };

  publicAPI.pick = (selection, renderer) => {
    publicAPI.initialize();
    const pickResult = superClass.pick(selection, renderer);
    if (pickResult) {
      const camera = renderer.getActiveCamera();
      const cameraPos = [];
      camera.getPosition(cameraPos);

      if (camera.getParallelProjection()) {
        // For parallel projection, use -ve direction of projection
        const cameraFocus = [];
        camera.getFocalPoint(cameraFocus);
        model.pickNormal[0] = cameraPos[0] - cameraFocus[0];
        model.pickNormal[1] = cameraPos[1] - cameraFocus[1];
        model.pickNormal[2] = cameraPos[2] - cameraFocus[2];
      } else {
        // Get the vector from pick position to the camera
        model.pickNormal[0] = cameraPos[0] - model.pickPosition[0];
        model.pickNormal[1] = cameraPos[1] - model.pickPosition[1];
        model.pickNormal[2] = cameraPos[2] - model.pickPosition[2];
      }
      vtkMath.normalize(model.pickNormal);
    }
    return pickResult;
  };

  model.intersectWithLine = (p1, p2, tolerance, prop, mapper) => {
    let tMin = Number.MAX_VALUE;
    let t1 = 0.0;
    let t2 = 1.0;

    const vtkCellPickerPlaneTol = 1e-14;

    const clipLine = clipLineWithPlane(
      mapper,
      model.transformMatrix,
      p1,
      p2,
      t1,
      t2
    );
    if (mapper && !clipLine.intersect) {
      return Number.MAX_VALUE;
    }

    if (mapper.isA('vtkImageMapper') || mapper.isA('vtkImageArrayMapper')) {
      const pickData = mapper.intersectWithLineForCellPicking(p1, p2);
      if (pickData) {
        tMin = pickData.t;
        model.cellIJK = pickData.ijk;
        model.pCoords = pickData.pCoords;
      }
    } else if (mapper.isA('vtkVolumeMapper')) {
      // we calculate here the parametric intercept points between the ray and the bounding box, so
      // if the application defines for some reason a too large ray length (1e6), it restrict the calculation
      // to the vtkVolume prop bounding box
      const interceptionObject = vtkBox.intersectWithLine(
        mapper.getBounds(),
        p1,
        p2
      );

      t1 =
        interceptionObject?.t1 > clipLine.t1
          ? interceptionObject.t1
          : clipLine.t1;
      t2 =
        interceptionObject?.t2 < clipLine.t2
          ? interceptionObject.t2
          : clipLine.t2;

      tMin = model.intersectVolumeWithLine(p1, p2, t1, t2, tolerance, prop);
    } else if (mapper.isA('vtkMapper')) {
      tMin = model.intersectActorWithLine(p1, p2, t1, t2, tolerance, mapper);
    }

    if (tMin < model.globalTMin) {
      model.globalTMin = tMin;
      if (
        Math.abs(tMin - t1) < vtkCellPickerPlaneTol &&
        clipLine.clippingPlaneId >= 0
      ) {
        model.mapperPosition[0] = p1[0] * (1 - t1) + p2[0] * t1;
        model.mapperPosition[1] = p1[1] * (1 - t1) + p2[1] * t1;
        model.mapperPosition[2] = p1[2] * (1 - t1) + p2[2] * t1;
        const plane = [];
        mapper.getClippingPlaneInDataCoords(
          model.transformMatrix,
          clipLine.clippingPlaneId,
          plane
        );
        vtkMath.normalize(plane);
        // Want normal outward from the planes, not inward
        model.mapperNormal[0] = -plane[0];
        model.mapperNormal[1] = -plane[1];
        model.mapperNormal[2] = -plane[2];
      }
      vec3.transformMat4(
        model.pickPosition,
        model.mapperPosition,
        model.transformMatrix
      );
      // Transform vector
      const mat = model.transformMatrix;
      model.mapperNormal[0] =
        mat[0] * model.pickNormal[0] +
        mat[4] * model.pickNormal[1] +
        mat[8] * model.pickNormal[2];
      model.mapperNormal[1] =
        mat[1] * model.pickNormal[0] +
        mat[5] * model.pickNormal[1] +
        mat[9] * model.pickNormal[2];
      model.mapperNormal[2] =
        mat[2] * model.pickNormal[0] +
        mat[6] * model.pickNormal[1] +
        mat[10] * model.pickNormal[2];
    }
    return tMin;
  };

  model.intersectVolumeWithLine = (p1, p2, t1, t2, tolerance, volume) => {
    let tMin = Number.MAX_VALUE;
    const mapper = volume.getMapper();
    const imageData = mapper.getInputData();
    const dims = imageData.getDimensions();
    const scalars = imageData.getPointData().getScalars().getData();
    const extent = imageData.getExtent();
    // get the world to index transform to correctly transform from world to volume index
    const imageTransform = imageData.getWorldToIndex();

    // calculate opacity table
    const numIComps = 1;
    const oWidth = 1024;
    const tmpTable = new Float32Array(oWidth);
    const opacityArray = new Float32Array(oWidth);
    let ofun;
    let oRange;
    const sampleDist = volume.getMapper().getSampleDistance();

    for (let c = 0; c < numIComps; ++c) {
      ofun = volume.getProperty().getScalarOpacity(c);
      oRange = ofun.getRange();
      ofun.getTable(oRange[0], oRange[1], oWidth, tmpTable, 1);
      const opacityFactor =
        sampleDist / volume.getProperty().getScalarOpacityUnitDistance(c);

      // adjust for sample distance etc
      for (let i = 0; i < oWidth; ++i) {
        opacityArray[i] = 1.0 - (1.0 - tmpTable[i]) ** opacityFactor;
      }
    }
    const scale = oWidth / (oRange[1] - oRange[0] + 1);

    // Make a new p1 and p2 using the clipped t1 and t2
    const q1 = [0, 0, 0, 1];
    const q2 = [0, 0, 0, 1];
    q1[0] = p1[0];
    q1[1] = p1[1];
    q1[2] = p1[2];
    q2[0] = p2[0];
    q2[1] = p2[1];
    q2[2] = p2[2];
    if (t1 !== 0.0 || t2 !== 1.0) {
      for (let j = 0; j < 3; j++) {
        q1[j] = p1[j] * (1.0 - t1) + p2[j] * t1;
        q2[j] = p1[j] * (1.0 - t2) + p2[j] * t2;
      }
    }

    // convert q1, q2 world coordinates to x1, x2 volume index coordinates
    const x1 = [0, 0, 0, 0];
    const x2 = [0, 0, 0, 0];
    vec4.transformMat4(x1, q1, imageTransform);
    vec4.transformMat4(x2, q2, imageTransform);

    const x = [0, 0, 0];
    const xi = [0, 0, 0];

    const sliceSize = dims[1] * dims[0];
    const rowSize = dims[0];
    // here the step is the 1 over the distance between volume index location x1 and x2
    const step = 1 / Math.sqrt(vtkMath.distance2BetweenPoints(x1, x2));
    let insideVolume;
    // here we reinterpret the t value as the distance between x1 and x2
    // When calculating the tMin, we weight t between t1 and t2 values
    for (let t = 0; t < 1; t += step) {
      // calculate the location of the point
      insideVolume = true;
      for (let j = 0; j < 3; j++) {
        // "t" is the fractional distance between endpoints x1 and x2
        x[j] = x1[j] * (1.0 - t) + x2[j] * t;
      }
      for (let j = 0; j < 3; j++) {
        // Bounds check
        if (x[j] < extent[2 * j]) {
          x[j] = extent[2 * j];
          insideVolume = false;
        } else if (x[j] > extent[2 * j + 1]) {
          x[j] = extent[2 * j + 1];
          insideVolume = false;
        }

        xi[j] = Math.round(x[j]);
      }

      if (insideVolume) {
        const index = xi[2] * sliceSize + xi[1] * rowSize + xi[0];
        let value = scalars[index];
        if (value < oRange[0]) {
          value = oRange[0];
        } else if (value > oRange[1]) {
          value = oRange[1];
        }
        value = Math.floor((value - oRange[0]) * scale);
        const opacity = tmpTable[value];
        if (opacity > model.opacityThreshold) {
          // returning the tMin to the original scale, if t1 > 0 or t2 < 1
          tMin = t1 * (1.0 - t) + t2 * t;
          break;
        }
      }
    }

    return tMin;
  };

  model.intersectActorWithLine = (p1, p2, t1, t2, tolerance, mapper) => {
    let tMin = Number.MAX_VALUE;
    const minXYZ = [0, 0, 0];
    let pDistMin = Number.MAX_VALUE;
    const minPCoords = [0, 0, 0];
    let minCellId = null;
    let minCell = null;
    let minCellType = null;
    let subId = null;
    const x = [];
    const data = mapper.getInputData();
    const isPolyData = 1;

    // Make a new p1 and p2 using the clipped t1 and t2
    const q1 = [0, 0, 0];
    const q2 = [0, 0, 0];
    q1[0] = p1[0];
    q1[1] = p1[1];
    q1[2] = p1[2];
    q2[0] = p2[0];
    q2[1] = p2[1];
    q2[2] = p2[2];
    if (t1 !== 0.0 || t2 !== 1.0) {
      for (let j = 0; j < 3; j++) {
        q1[j] = p1[j] * (1.0 - t1) + p2[j] * t1;
        q2[j] = p1[j] * (1.0 - t2) + p2[j] * t2;
      }
    }

    const locator = null;
    if (locator) {
      // TODO when cell locator will be implemented
    } else if (data.getCells) {
      if (!data.getCells()) {
        data.buildLinks();
      }

      const tempCellMap = createCellMap();
      const minCellMap = createCellMap();

      const numberOfCells = data.getNumberOfCells();

      /* eslint-disable no-continue */
      for (let cellId = 0; cellId < numberOfCells; cellId++) {
        const pCoords = [0, 0, 0];

        minCellType = data.getCellType(cellId);

        // Skip cells that are marked as empty
        if (minCellType === CellType.VTK_EMPTY_CELL) {
          continue;
        }

        const cell = tempCellMap[minCellType];

        if (cell == null) {
          continue;
        }

        minCell = minCellMap[minCellType];

        data.getCell(cellId, cell);

        let cellPicked;

        if (isPolyData) {
          if (vtkCellTypes.hasSubCells(minCellType)) {
            cellPicked = cell.intersectWithLine(
              t1,
              t2,
              p1,
              p2,
              tolerance,
              x,
              pCoords
            );
          } else {
            cellPicked = cell.intersectWithLine(p1, p2, tolerance, x, pCoords);
          }
        } else {
          cellPicked = cell.intersectWithLine(q1, q2, tolerance, x, pCoords);
          if (t1 !== 0.0 || t2 !== 1.0) {
            cellPicked.t = t1 * (1.0 - cellPicked.t) + t2 * cellPicked.t;
          }
        }

        if (
          cellPicked.intersect === 1 &&
          cellPicked.t <= tMin + model.tolerance &&
          cellPicked.t >= t1 &&
          cellPicked.t <= t2
        ) {
          const pDist = cell.getParametricDistance(pCoords);

          if (pDist < pDistMin || (pDist === pDistMin && cellPicked.t < tMin)) {
            tMin = cellPicked.t;
            pDistMin = pDist;
            subId = cellPicked.subId;
            minCellId = cellId;
            cell.deepCopy(minCell);
            for (let k = 0; k < 3; k++) {
              minXYZ[k] = x[k];
              minPCoords[k] = pCoords[k];
            }
          }
        }
      }
      /* eslint-enable no-continue */
    }

    if (minCellId >= 0 && tMin < model.globalTMin) {
      resetPickInfo();
      const nbPointsInCell = minCell.getNumberOfPoints();
      const weights = new Array(nbPointsInCell);
      for (let i = 0; i < nbPointsInCell; i++) {
        weights[i] = 0.0;
      }
      const point = [];

      if (vtkCellTypes.hasSubCells(minCellType)) {
        minCell.evaluateLocation(subId, minPCoords, point, weights);
      } else {
        minCell.evaluateLocation(minPCoords, point, weights);
      }

      // Return the polydata to the user
      model.dataSet = data;
      model.cellId = minCellId;
      model.pCoords[0] = minPCoords[0];
      model.pCoords[1] = minPCoords[1];
      model.pCoords[2] = minPCoords[2];

      // Find the point with the maximum weight
      let maxWeight = 0;
      let iMaxWeight = -1;
      for (let i = 0; i < nbPointsInCell; i++) {
        if (weights[i] > maxWeight) {
          iMaxWeight = i;
          maxWeight = weights[i];
        }
      }

      // If maximum weight is found, use it to get the PointId
      if (iMaxWeight !== -1) {
        model.pointId = minCell.getPointsIds()[iMaxWeight];
      }

      // Set the mapper position
      model.mapperPosition[0] = minXYZ[0];
      model.mapperPosition[1] = minXYZ[1];
      model.mapperPosition[2] = minXYZ[2];

      // Compute the normal
      if (
        !publicAPI.computeSurfaceNormal(
          data,
          minCell,
          weights,
          model.mapperNormal
        )
      ) {
        // By default, the normal points back along view ray
        model.mapperNormal[0] = p1[0] - p2[0];
        model.mapperNormal[1] = p1[1] - p2[1];
        model.mapperNormal[2] = p1[2] - p2[2];
        vtkMath.normalize(model.mapperNormal);
      }
    }

    return tMin;
  };
}

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

const DEFAULT_VALUES = {
  cellId: -1,
  pCoords: [],
  cellIJK: [],
  pickNormal: [],
  mapperNormal: [],
  opacityThreshold: 0.2,
};

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

export function extend(publicAPI, model, initialValues = {}) {
  Object.assign(model, DEFAULT_VALUES, initialValues);

  // Inheritance
  vtkPicker.extend(publicAPI, model, initialValues);

  macro.getArray(publicAPI, model, [
    'pickNormal',
    'mapperNormal',
    'pCoords',
    'cellIJK',
  ]);

  macro.setGet(publicAPI, model, ['opacityThreshold']);

  macro.get(publicAPI, model, ['cellId']);

  // Object methods
  vtkCellPicker(publicAPI, model);
}

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

export const newInstance = macro.newInstance(extend, 'vtkCellPicker');

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

export default { newInstance, extend, ...STATIC };