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  ./demo/canvas-001.js ./demo/canvas-002.js ./demo/canvas-003.js ./demo/canvas-004.js ./demo/canvas-005.js ./demo/canvas-006.js ./demo/canvas-007.js ./demo/canvas-008.js ./demo/canvas-009.js ./demo/canvas-010.js ./demo/canvas-011.js ./demo/canvas-012.js ./demo/canvas-013.js ./demo/canvas-014.js ./demo/canvas-015.js ./demo/canvas-015a.js ./demo/canvas-016.js ./demo/canvas-017.js ./demo/canvas-018.js ./demo/canvas-019.js ./demo/canvas-019a.js ./demo/canvas-020.js ./demo/canvas-021.js ./demo/canvas-022.js ./demo/canvas-023.js ./demo/canvas-024.js ./demo/canvas-025.js ./demo/canvas-026.js ./demo/canvas-027.js ./demo/canvas-028.js ./demo/canvas-029.js ./demo/canvas-030.js ./demo/canvas-031.js ./demo/canvas-032.js ./demo/canvas-033.js ./demo/canvas-034.js ./demo/canvas-035.js ./demo/canvas-036.js ./demo/canvas-037.js ./demo/canvas-038.js ./demo/canvas-039.js ./demo/canvas-040.js ./demo/canvas-041.js ./demo/canvas-042.js ./demo/canvas-043.js ./demo/canvas-044.js ./demo/canvas-045.js ./demo/canvas-046.js ./demo/canvas-047.js ./demo/canvas-048.js ./demo/canvas-049.js ./demo/canvas-050.js ./demo/canvas-051.js ./demo/canvas-052.js ./demo/canvas-053.js ./demo/canvas-054.js ./demo/canvas-055.js ./demo/canvas-056.js ./demo/canvas-058.js ./demo/canvas-059.js ./demo/canvas-060.js ./demo/canvas-061.js ./demo/canvas-062.js ./demo/canvas-063.js ./demo/canvas-064.js ./demo/core-001.js ./demo/delaunator-001.js ./demo/delaunator-002.js ./demo/dom-001.js ./demo/dom-002.js ./demo/dom-003.js ./demo/dom-004.js ./demo/dom-005.js ./demo/dom-006.js ./demo/dom-007.js ./demo/dom-008.js ./demo/dom-009.js ./demo/dom-010.js ./demo/dom-011.js ./demo/dom-012.js ./demo/dom-013.js ./demo/dom-015.js ./demo/dom-016.js ./demo/dom-017.js ./demo/dom-018.js ./demo/filters-001.js ./demo/filters-002.js ./demo/filters-002a.js ./demo/filters-003.js ./demo/filters-004.js ./demo/filters-005.js ./demo/filters-006.js ./demo/filters-007.js ./demo/filters-008.js ./demo/filters-009.js ./demo/filters-010.js ./demo/filters-011.js ./demo/filters-012.js ./demo/filters-013.js ./demo/filters-014.js ./demo/filters-015.js ./demo/filters-016.js ./demo/filters-017.js ./demo/filters-018.js ./demo/filters-019.js ./demo/filters-020.js ./demo/filters-021.js ./demo/filters-022.js ./demo/filters-023.js ./demo/filters-024.js ./demo/filters-025.js ./demo/filters-026.js ./demo/filters-027.js ./demo/filters-028.js ./demo/filters-101.js ./demo/filters-102.js ./demo/filters-103.js ./demo/filters-104.js ./demo/filters-105.js ./demo/filters-501.js ./demo/filters-502.js ./demo/filters-503.js ./demo/filters-504.js ./demo/filters-505.js ./demo/mediapipe-001.js ./demo/mediapipe-002.js ./demo/mediapipe-003.js ./demo/modules-001.js ./demo/modules-002.js ./demo/modules-003.js ./demo/modules-004.js ./demo/modules-005.js ./demo/modules-006.js ./demo/packets-001.js ./demo/packets-002.js ./demo/particles-001.js ./demo/particles-002.js ./demo/particles-003.js ./demo/particles-004.js ./demo/particles-005.js ./demo/particles-006.js ./demo/particles-007.js ./demo/particles-008.js ./demo/particles-009.js ./demo/particles-010.js ./demo/particles-011.js ./demo/particles-012.js ./demo/particles-013.js ./demo/particles-014.js ./demo/particles-015.js ./demo/particles-016.js ./demo/rapier-001.js ./demo/snippets-001.js ./demo/snippets-002.js ./demo/snippets-003.js ./demo/snippets-004.js ./demo/snippets-005.js ./demo/snippets-006.js ./demo/tensorflow-001.js ./demo/tensorflow-002.js ./demo/utilities.js

- §

  # Demo Particles 011

  Tracer entity: generation and functionality

- §

  Run code

      import * as scrawl from '../source/scrawl.js'

      import { reportSpeed } from './utilities.js';

- §

  #### Scene setup

      const canvas = scrawl.library.artefact.mycanvas;

- §

  Define some filters

      scrawl.makeFilter({
          name: 'grayscale',
          method: 'grayscale',
      }).clone({
          name: 'invert',
          method: 'invert',
      });

      scrawl.makeFilter({
          name: 'tint',
          method: 'tint',
          redInRed: 0.5,      redInGreen: 1,      redInBlue: 0.9,
          greenInRed: 0,      greenInGreen: 0.3,  greenInBlue: 0.8,
          blueInRed: 0.8,     blueInGreen: 0.8,   blueInBlue: 0.4,
      });

      scrawl.makeFilter({
          name: 'matrix',
          method: 'matrix',
          weights: [-1, -1, 0, -1, 1, 1, 0, 1, 1],
      });

- §

  Create a Shape entity to act as a path for our Tracer entitys

      scrawl.makeShape({

          name: 'my-arrow',

          pathDefinition: 'M266.2,703.1 h-178 L375.1,990 l287-286.9 H481.9 C507.4,365,683.4,91.9,911.8,25.5 877,15.4,840.9,10,803.9,10 525.1,10,295.5,313.4,266.2,703.1 z',

          start: ['center', 'center'],
          handle: ['center', 'center'],

          scale: 0.4,
          roll: -70,
          flipUpend: true,

          useAsPath: true,

          strokeStyle: 'gray',
          fillStyle: 'lavender',
          lineWidth: 8,
          method: 'fillThenDraw',

          bringToFrontOnDrag: false,
      });

- §

  #### Particle physics animation scene

- §

  Tracer entitys don’t have any color control built in; we need to create our own color factory

      const colorFactory = scrawl.makeColor({

          name: 'tracer-3-color-factory',

          minimumColor: 'red',
          maximumColor: 'blue',

          colorSpace: 'LAB',
      });

- §

  Create a Tracer entity

  - Note that Tracers do not require a World object, cannot process Force objects, and cannot be connected together using Spring objects.

      scrawl.makeTracer({

          name: 'trace-1',

          historyLength: 50,

- §

  We will delta-animate this Tracer alonbg the path of our Shape entity

          path: 'my-arrow',
          pathPosition: 0,
          lockTo: 'path',

          delta: {
              pathPosition: 0.002,
          },

          artefact: scrawl.makeWheel({

              name: 'burn-1',

              radius: 6,

              handle: ['center', 'center'],

              fillStyle: 'red',
              method: 'fill',
              visibility: false,

              noUserInteraction: true,
              noPositionDependencies: true,
              noFilters: true,
              noDeltaUpdates: true,
          }),

- §

  This Tracer will produce a ‘dashed’ effect, by displaying discrete ranges of its history

          stampAction: function (artefact, particle, host) {

              const history = particle.history;

              let start;

              history.forEach((p, index) => {

                  if (index < 10 || (index > 20 && index < 30) || index > 40) {

                      [ , , ...start] = p;
                      artefact.simpleStamp(host, { start });
                  }
              });
          },

- §

  Clone the Tracer entity

      }).clone({

          name: 'trace-2',
          pathPosition: 0.33,

          artefact: scrawl.library.artefact['burn-1'].clone({
              name: 'burn-2',
              fillStyle: 'green',
              globalAlpha: 0.2,
          }),

- §

  Our second Tracer shows a ‘tail-fade’ effect

          stampAction: function (artefact, particle, host) {

              const history = particle.history,
                  len = history.length;

              let start;

              history.forEach((p, index) => {

                  if (index % 3 === 0) {

                      [ , , ...start] = p;

                      artefact.simpleStamp(host, {
                          start,
                          globalAlpha: (len - index) / len,
                      });
                  }
              });
          },

- §

  Clone the second Tracer entity

      }).clone({

          name: 'trace-3',
          pathPosition: 0.67,

          artefact: scrawl.library.artefact['burn-1'].clone({
              name: 'burn-3',
              fillStyle: 'blue',
          }),

- §

  This Tracer varies its scale to create a ‘teardrop’ effect

          stampAction: function (artefact, particle, host) {

              const history = particle.history,
                  len = history.length;

              let start;

              history.forEach((p, index) => {

                  [ , , ...start] = p;

                  const magicNumber = (len - index) / len;

                  artefact.simpleStamp(host, {
                      start,
                      scale: magicNumber * 3,
                      fillStyle: colorFactory.getRangeColor(magicNumber),
                  });
              });
          },
      });

- §

  #### Scene animation

  Function to display frames-per-second data, and other information relevant to the demo

      const report = reportSpeed('#reportmessage');

- §

  Create the Display cycle animation

      scrawl.makeRender({

          name: 'demo-animation',
          target: canvas,
          afterShow: report,
      });

- §

  #### User interaction

  Make the arrow draggable

  - KNOWN BUG - the arrow is not draggable on first user mousedown, but is draggable afterwards

      scrawl.makeGroup({

          name: 'my-draggable-group',

      }).addArtefacts('my-arrow');

      scrawl.makeDragZone({

          zone: canvas,
          collisionGroup: 'my-draggable-group',
          endOn: ['up', 'leave'],
          preventTouchDefaultWhenDragging: true,
      });

- §

  Action user choice to apply a filter to a Tracer entity

      const filterChoice = function (e) {

          e.preventDefault();
          e.returnValue = false;

          const val = e.target.value,
              entity = scrawl.library.entity['trace-2'];

          entity.clearFilters();
          if (val) entity.addFilters(val);
      };
      scrawl.addNativeListener(['input', 'change'], filterChoice, '#filter');

- §

  @ts-expect-error

      document.querySelector('#filter').value = '';

- §

  #### Development and testing

      console.log(scrawl.library);