CylinderOutlineGeometry.js

import BoundingSphere from "./BoundingSphere.js";
import Cartesian2 from "./Cartesian2.js";
import Cartesian3 from "./Cartesian3.js";
import Check from "./Check.js";
import ComponentDatatype from "./ComponentDatatype.js";
import CylinderGeometryLibrary from "./CylinderGeometryLibrary.js";
import defaultValue from "./defaultValue.js";
import defined from "./defined.js";
import DeveloperError from "./DeveloperError.js";
import Geometry from "./Geometry.js";
import GeometryAttribute from "./GeometryAttribute.js";
import GeometryAttributes from "./GeometryAttributes.js";
import GeometryOffsetAttribute from "./GeometryOffsetAttribute.js";
import IndexDatatype from "./IndexDatatype.js";
import PrimitiveType from "./PrimitiveType.js";

const radiusScratch = new Cartesian2();

/**
 * A description of the outline of a cylinder.
 *
 * @alias CylinderOutlineGeometry
 * @constructor
 *
 * @param {Object} options Object with the following properties:
 * @param {Number} options.length The length of the cylinder.
 * @param {Number} options.topRadius The radius of the top of the cylinder.
 * @param {Number} options.bottomRadius The radius of the bottom of the cylinder.
 * @param {Number} [options.slices=128] The number of edges around the perimeter of the cylinder.
 * @param {Number} [options.numberOfVerticalLines=16] Number of lines to draw between the top and bottom surfaces of the cylinder.
 *
 * @exception {DeveloperError} options.length must be greater than 0.
 * @exception {DeveloperError} options.topRadius must be greater than 0.
 * @exception {DeveloperError} options.bottomRadius must be greater than 0.
 * @exception {DeveloperError} bottomRadius and topRadius cannot both equal 0.
 * @exception {DeveloperError} options.slices must be greater than or equal to 3.
 *
 * @see CylinderOutlineGeometry.createGeometry
 *
 * @example
 * // create cylinder geometry
 * const cylinder = new Cesium.CylinderOutlineGeometry({
 *     length: 200000,
 *     topRadius: 80000,
 *     bottomRadius: 200000,
 * });
 * const geometry = Cesium.CylinderOutlineGeometry.createGeometry(cylinder);
 */
function CylinderOutlineGeometry(options) {
  options = defaultValue(options, defaultValue.EMPTY_OBJECT);

  const length = options.length;
  const topRadius = options.topRadius;
  const bottomRadius = options.bottomRadius;
  const slices = defaultValue(options.slices, 128);
  const numberOfVerticalLines = Math.max(
    defaultValue(options.numberOfVerticalLines, 16),
    0
  );

  //>>includeStart('debug', pragmas.debug);
  Check.typeOf.number("options.positions", length);
  Check.typeOf.number("options.topRadius", topRadius);
  Check.typeOf.number("options.bottomRadius", bottomRadius);
  Check.typeOf.number.greaterThanOrEquals("options.slices", slices, 3);
  if (
    defined(options.offsetAttribute) &&
    options.offsetAttribute === GeometryOffsetAttribute.TOP
  ) {
    throw new DeveloperError(
      "GeometryOffsetAttribute.TOP is not a supported options.offsetAttribute for this geometry."
    );
  }
  //>>includeEnd('debug');

  this._length = length;
  this._topRadius = topRadius;
  this._bottomRadius = bottomRadius;
  this._slices = slices;
  this._numberOfVerticalLines = numberOfVerticalLines;
  this._offsetAttribute = options.offsetAttribute;
  this._workerName = "createCylinderOutlineGeometry";
}

/**
 * The number of elements used to pack the object into an array.
 * @type {Number}
 */
CylinderOutlineGeometry.packedLength = 6;

/**
 * Stores the provided instance into the provided array.
 *
 * @param {CylinderOutlineGeometry} value The value to pack.
 * @param {Number[]} array The array to pack into.
 * @param {Number} [startingIndex=0] The index into the array at which to start packing the elements.
 *
 * @returns {Number[]} The array that was packed into
 */
CylinderOutlineGeometry.pack = function (value, array, startingIndex) {
  //>>includeStart('debug', pragmas.debug);
  Check.typeOf.object("value", value);
  Check.defined("array", array);
  //>>includeEnd('debug');

  startingIndex = defaultValue(startingIndex, 0);

  array[startingIndex++] = value._length;
  array[startingIndex++] = value._topRadius;
  array[startingIndex++] = value._bottomRadius;
  array[startingIndex++] = value._slices;
  array[startingIndex++] = value._numberOfVerticalLines;
  array[startingIndex] = defaultValue(value._offsetAttribute, -1);

  return array;
};

const scratchOptions = {
  length: undefined,
  topRadius: undefined,
  bottomRadius: undefined,
  slices: undefined,
  numberOfVerticalLines: undefined,
  offsetAttribute: undefined,
};

/**
 * Retrieves an instance from a packed array.
 *
 * @param {Number[]} array The packed array.
 * @param {Number} [startingIndex=0] The starting index of the element to be unpacked.
 * @param {CylinderOutlineGeometry} [result] The object into which to store the result.
 * @returns {CylinderOutlineGeometry} The modified result parameter or a new CylinderOutlineGeometry instance if one was not provided.
 */
CylinderOutlineGeometry.unpack = function (array, startingIndex, result) {
  //>>includeStart('debug', pragmas.debug);
  Check.defined("array", array);
  //>>includeEnd('debug');

  startingIndex = defaultValue(startingIndex, 0);

  const length = array[startingIndex++];
  const topRadius = array[startingIndex++];
  const bottomRadius = array[startingIndex++];
  const slices = array[startingIndex++];
  const numberOfVerticalLines = array[startingIndex++];
  const offsetAttribute = array[startingIndex];

  if (!defined(result)) {
    scratchOptions.length = length;
    scratchOptions.topRadius = topRadius;
    scratchOptions.bottomRadius = bottomRadius;
    scratchOptions.slices = slices;
    scratchOptions.numberOfVerticalLines = numberOfVerticalLines;
    scratchOptions.offsetAttribute =
      offsetAttribute === -1 ? undefined : offsetAttribute;
    return new CylinderOutlineGeometry(scratchOptions);
  }

  result._length = length;
  result._topRadius = topRadius;
  result._bottomRadius = bottomRadius;
  result._slices = slices;
  result._numberOfVerticalLines = numberOfVerticalLines;
  result._offsetAttribute =
    offsetAttribute === -1 ? undefined : offsetAttribute;

  return result;
};

/**
 * Computes the geometric representation of an outline of a cylinder, including its vertices, indices, and a bounding sphere.
 *
 * @param {CylinderOutlineGeometry} cylinderGeometry A description of the cylinder outline.
 * @returns {Geometry|undefined} The computed vertices and indices.
 */
CylinderOutlineGeometry.createGeometry = function (cylinderGeometry) {
  let length = cylinderGeometry._length;
  const topRadius = cylinderGeometry._topRadius;
  const bottomRadius = cylinderGeometry._bottomRadius;
  const slices = cylinderGeometry._slices;
  const numberOfVerticalLines = cylinderGeometry._numberOfVerticalLines;

  if (
    length <= 0 ||
    topRadius < 0 ||
    bottomRadius < 0 ||
    (topRadius === 0 && bottomRadius === 0)
  ) {
    return;
  }

  const numVertices = slices * 2;

  const positions = CylinderGeometryLibrary.computePositions(
    length,
    topRadius,
    bottomRadius,
    slices,
    false
  );
  let numIndices = slices * 2;
  let numSide;
  if (numberOfVerticalLines > 0) {
    const numSideLines = Math.min(numberOfVerticalLines, slices);
    numSide = Math.round(slices / numSideLines);
    numIndices += numSideLines;
  }

  const indices = IndexDatatype.createTypedArray(numVertices, numIndices * 2);
  let index = 0;
  let i;
  for (i = 0; i < slices - 1; i++) {
    indices[index++] = i;
    indices[index++] = i + 1;
    indices[index++] = i + slices;
    indices[index++] = i + 1 + slices;
  }

  indices[index++] = slices - 1;
  indices[index++] = 0;
  indices[index++] = slices + slices - 1;
  indices[index++] = slices;

  if (numberOfVerticalLines > 0) {
    for (i = 0; i < slices; i += numSide) {
      indices[index++] = i;
      indices[index++] = i + slices;
    }
  }

  const attributes = new GeometryAttributes();
  attributes.position = new GeometryAttribute({
    componentDatatype: ComponentDatatype.DOUBLE,
    componentsPerAttribute: 3,
    values: positions,
  });

  radiusScratch.x = length * 0.5;
  radiusScratch.y = Math.max(bottomRadius, topRadius);

  const boundingSphere = new BoundingSphere(
    Cartesian3.ZERO,
    Cartesian2.magnitude(radiusScratch)
  );

  if (defined(cylinderGeometry._offsetAttribute)) {
    length = positions.length;
    const offsetValue =
      cylinderGeometry._offsetAttribute === GeometryOffsetAttribute.NONE
        ? 0
        : 1;
    const applyOffset = new Uint8Array(length / 3).fill(offsetValue);
    attributes.applyOffset = new GeometryAttribute({
      componentDatatype: ComponentDatatype.UNSIGNED_BYTE,
      componentsPerAttribute: 1,
      values: applyOffset,
    });
  }

  return new Geometry({
    attributes: attributes,
    indices: indices,
    primitiveType: PrimitiveType.LINES,
    boundingSphere: boundingSphere,
    offsetAttribute: cylinderGeometry._offsetAttribute,
  });
};
export default CylinderOutlineGeometry;