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- §

  # Star factory

  A factory for generating star shape-based entitys

  Path-defined entitys represent a diverse range of shapes rendered onto a DOM <canvas> element using the Canvas API’s Path2D interface. They use the shapeBasic and shapePathCalculation (some also use shapeCurve) mixins to define much of their functionality.

  All path-defined entitys can be positioned, cloned, filtered etc:

  - Positioning functionality for the entity is supplied by the position mixin, while rendering functionality comes from the entity mixin.
  - Dimensions, however, have little meaning for path-defined entitys - their width and height are determined by their SVG path data Strings; use `scale` instead.
  - Path-defined entitys can use CSS color Strings for their fillStyle and strokeStyle values, alongside Gradient, RadialGradient, Color and Pattern objects.
  - They will also accept Filter objects.
  - They can use Anchor objects for user navigation.
  - They can be rendered to the canvas by including them in a Cell object’s Group.
  - They can be animated directly, or using delta animation, or act as the target for Tween animations.
  - Path-defined entitys can be cloned, and killed.
- §

  #### Using path-defined entitys as Scrawl-canvas paths

  A path is a track - straight, or curved, or as complex as required - placed across a container which artefacts can use as a source of their positioning data. We can animate an artifact to move along the path:

  - To enable a path-defined entity to be used as a path by other artefacts, set its `useAsPath` flag to `true`.
  - The artefact can then set its `path` attribute to the path-defined entity’s name-String (or the entity itself), and set its `lockTo` Array values to `"path"`.
  - We position the artefact by setting its `pathPosition` attribute to a float Number value between `0.0 - 1.0`, with `0` being the start of the path, and `1` being its end.
  - Path-defined entitys can use other path-defined entitys as a path.
  - Phrase entitys can use a path to position their text block; they can also use a path to position each letter individually along the path.
  - Artefacts (and letters) can be rotated so that they match the rotation at that point along the path - tangential rotation by setting their `addPathRotation` flag to `true`.
  - Animate an artefact along the path by either using the artefact’s `delta` object, or triggering a Tween to perform the movement.
- §

  #### Demos:

  - Canvas-011 - Shape entity (make, clone, method); drag and drop shape entitys
  - Canvas-012 - Shape entity position; shape entity as a path for other artefacts to follow
  - Canvas-013 - Path-defined entitys: oval, rectangle, line, quadratic, bezier, tetragon, polygon, star, spiral
  - Canvas-014 - Line, quadratic and bezier entitys - control lock alternatives
  - Canvas-018 - Phrase entity - text along a path
  - Canvas-024 - Loom entity functionality
  - Canvas-030 - Polyline entity functionality
  - Canvas-038 - Responsive Shape-based entitys
  - DOM-015 - Use stacked DOM artefact corners as pivot points
  - Packets-002 - Scrawl-canvas packets - save and load a range of different entitys
- §

  #### Imports

      import { constructors } from '../core/library.js';

      import { doCreate, mergeOver, Ωempty } from '../core/utilities.js';

      import { releaseVector, requestVector } from './vector.js';

      import { releaseArray, requestArray } from './array-pool.js';

      import baseMix from '../mixin/base.js';
      import shapeMix from '../mixin/shape-basic.js';

      import { _abs, _min, ENTITY, STAR, T_STAR, ZERO_STR } from '../core/shared-vars.js';

- §

  #### Star constructor

      const Star = function (items = Ωempty) {

          this.shapeInit(items);
          return this;
      };

- §

  #### Star prototype

      const P = Star.prototype = doCreate();
      P.type = T_STAR;
      P.lib = ENTITY;
      P.isArtefact = true;
      P.isAsset = false;

- §

  #### Mixins

  - base
  - shapeBasic

      baseMix(P);
      shapeMix(P);

- §

  #### Star attributes

  - Attributes defined in the base mixin: name.
  - Attributes defined in the position mixin: group, visibility, order, calculateOrder, stampOrder, start, startX, startY, handle, handleX, handleY, offset, offsetX, offsetY, dimensions, width, height, pivoted, mimicked, lockTo, lockXTo, lockYTo, scale, roll, noUserInteraction, noPositionDependencies, noCanvasEngineUpdates, noFilters, noPathUpdates, purge, bringToFrontOnDrag.
  - Attributes defined in the delta mixin: delta, noDeltaUpdates.
  - Attributes defined in the pivot mixin: pivot, pivotCorner, addPivotHandle, addPivotOffset, addPivotRotation.
  - Attributes defined in the mimic mixin: mimic, useMimicDimensions, useMimicScale, useMimicStart, useMimicHandle, useMimicOffset, useMimicRotation, useMimicFlip, addOwnDimensionsToMimic, addOwnScaleToMimic, addOwnStartToMimic, addOwnHandleToMimic, addOwnOffsetToMimic, addOwnRotationToMimic.
  - Attributes defined in the path mixin: path, pathPosition, addPathHandle, addPathOffset, addPathRotation, constantPathSpeed.
  - Attributes defined in the entity mixin: method, pathObject, winding, flipReverse, flipUpend, scaleOutline, lockFillStyleToEntity, lockStrokeStyleToEntity, onEnter, onLeave, onDown, onUp, fillStyle, strokeStyle, globalAlpha, globalCompositeOperation, lineWidth, lineCap, lineJoin, lineDash, lineDashOffset, miterLimit, shadowOffsetX, shadowOffsetY, shadowBlur, shadowColor, filter.
  - Attributes defined in the anchor mixin: anchor.
  - Attributes defined in the filter mixin: filters, isStencil.
  - Attributes defined in the shapeBasic mixin: species, useAsPath, precision, pathDefinition, showBoundingBox, boundingBoxColor, minimumBoundingBoxDimensions, constantPathSpeed.

      const defaultAttributes = {

          radius1: 0,
          radius2: 0,
          points: 0,
          twist: 0,
      };
      P.defs = mergeOver(P.defs, defaultAttributes);

- §

  #### Packet management

  No additional packet functionality required

- §

  #### Clone management

  No additional clone functionality required

- §

  #### Kill management

  No additional kill functionality required

- §

  #### Get, Set, deltaSet

      const S = P.setters,
          D = P.deltaSetters;

- §

  radius1, radius2

      S.radius1 = function (item) {

          this.radius1 = item;
          this.updateDirty();
      };
      D.radius1 = function (item) {

          this.radius1 += item;
          this.updateDirty();
      };
      S.radius2 = function (item) {

          this.radius2 = item;
          this.updateDirty();
      };
      D.radius2 = function (item) {

          this.radius2 += item;
          this.updateDirty();
      };

- §

  points

      S.points = function (item) {

          this.points = item;
          this.updateDirty();
      };
      D.points = function (item) {

          this.points += item;
          this.updateDirty();
      };

- §

  twist

      S.twist = function (item) {

          this.twist = item;
          this.updateDirty();
      };
      D.twist = function (item) {

          this.twist += item;
          this.updateDirty();
      };

- §

  #### Prototype functions

- §

  `cleanSpecies` - internal helper function - called by `prepareStamp`

      P.cleanSpecies = function () {

          this.dirtySpecies = false;
          this.pathDefinition = this.makeStarPath();
      };

- §

  `makeStarPath` - internal helper function - called by `cleanSpecies`

      P.makeStarPath = function () {

          const points = this.points,
              twist = this.twist,
              turn = 360 / points,
              xPts = requestArray();

          let radius1 = this.radius1,
              radius2 = this.radius2;

          let currentX, currentY, x, y,
              myPath = ZERO_STR;

          if (radius1.substring || radius2.substring) {

              const host = this.getHost();

              if (host) {

                  const hW = host.currentDimensions[0];

                  radius1 = (radius1.substring) ? (parseFloat(radius1) / 100) * hW : radius1;
                  radius2 = (radius2.substring) ? (parseFloat(radius2) / 100) * hW : radius2;
              }
          }

          const v1 = requestVector({x: 0, y: -radius1}),
              v2 = requestVector({x: 0, y: -radius2});

          currentX = v1.x;
          currentY = v1.y;

          xPts.push(currentX);

          v2.rotate(-turn/2);
          v2.rotate(twist);

          for (let i = 0; i < points; i++) {

              v2.rotate(turn);

              x = parseFloat((v2.x - currentX).toFixed(1));
              currentX += x;
              xPts.push(currentX);

              y = parseFloat((v2.y - currentY).toFixed(1));
              currentY += y;

              myPath += `${x},${y} `;

              v1.rotate(turn);

              x = parseFloat((v1.x - currentX).toFixed(1));
              currentX += x;
              xPts.push(currentX);

              y = parseFloat((v1.y - currentY).toFixed(1));
              currentY += y;

              myPath += `${x},${y} `;

          }

          releaseVector(v1);
          releaseVector(v2);

          const myMin = _min(...xPts),
              myXoffset = _abs(myMin).toFixed(1);

          myPath = `m${myXoffset},0l${myPath}z`;

          releaseArray(xPts);

          return myPath;
      };

- §

  #### Factories

- §

  ##### makeStar

  Accepts argument with attributes:

  - radius1 (required) - the outer radius representing the distance between the center of the Shape and the tips of its (acute angle) points.
  - radius2 (required) - the inner radius representing the distance between the center of the Shape and the obtuse angle at the valley between the tips of its (acute angle) points.
  - … where these radius values are supplied as %Strings, they are calculated as relative to the canvas/cell width value.
  - points (required) - a positive integer Number representing the number of points the star will have.
  - twist - a float Number representing the degrees by which the star’s second radius will be rotated out of line from its first radius; the default value `0` will produce a star with all of its sides of equal length and the star’s valleys falling midway between its connecting points.
  - Note that the use of inner and outer above is purely descriptive: `radius2` can be larger than `radius1`

      scrawl.makeStar({

          name: '5star',

          startX: 20,
          startY: 100,

          radius1: 80,
          radius2: 50,

          points: 5,

          fillStyle: 'linen',
          method: 'fillAndDraw',
      });

      export const makeStar = function (items) {

          if (!items) return false;
          items.species = STAR;
          return new Star(items);
      };

      constructors.Star = Star;