Implemented "Clear Traces" tool

Readme.md

@@ -19,4 +19,9 @@ TODO
 - [ ] Zoom Easing
 - [ ] 2-touch Pan & Zoom
 - [ ] Multi-touch Mass Create
-- [ ] Tool to Clear Traces
+- [x] Tool to Clear Traces
+- [ ] Undo feature: 
+  - [ ] Undo "Clear Traces" Action
+  - [ ] Undo "Reset
+- [ ] Save to LocalStorage
+- [ ] Lossy Rescaling To Widen Zoom (Handling overflow/underflow)

config.js

@@ -9,13 +9,13 @@ export const DISPLAY_ACCELERATION_VECTORS = true;
 export const DISPLAY_PATH_TRACES = false;
 
 // VELOCITY
-export const VELOCITY_VECTOR_SCALE = 5E0;
+export const VELOCITY_VECTOR_SCALE = 8E0;
 export const VELOCITY_VECTOR_COLOR = 'rgba(150, 150, 150, 0.8)'; // optionally set to 'object color'
 export const VELOCITY_VECTOR_WIDTH = 1.5;
 export const VELOCITY_VECTOR_ARROWHEAD = true;
 
 // ACCELERATION
-export const ACCELERATION_VECTOR_SCALE = 5E0;
+export const ACCELERATION_VECTOR_SCALE = 8E0;
 export const ACCELERATION_VECTOR_COLOR = 'rgba(0, 128, 0, 0.8)'; // optionally set to 'object color'
 export const ACCELERATION_VECTOR_WIDTH = 1.5;
 export const ACCELERATION_VECTOR_ARROWHEAD = true;

display.js

@@ -1,22 +1,7 @@
 import {
-  ACCELERATION_VECTOR_ARROWHEAD,
-  ACCELERATION_VECTOR_COLOR,
-  ACCELERATION_VECTOR_SCALE,
-  ACCELERATION_VECTOR_WIDTH,
   ARROWHEAD_LENGTH,
   ARROWHEAD_WIDTH,
   DISPLAY_CANVAS_SIZE,
-  OFFSCREEN_OBJECT_ARROWHEAD_LENGTH,
-  OFFSCREEN_OBJECT_LINE_SCALE,
-  OFFSCREEN_OBJECT_LINE_WIDTH,
-  PATH_TRACES_COLOR,
-  PATH_TRACES_OPACITY,
-  PATH_TRACES_DASHED_OPACITY,
-  PATH_TRACES_WIDTH,
-  VELOCITY_VECTOR_ARROWHEAD,
-  VELOCITY_VECTOR_COLOR,
-  VELOCITY_VECTOR_SCALE,
-  VELOCITY_VECTOR_WIDTH,
 } from './config.js';
 
 export class Display {
@@ -86,139 +71,8 @@ export class Display {
     ctx.fillRect(this.viewOrigin.x, this.viewOrigin.y, this.width, this.height);
   }
 
-  drawObject(obj) {
-    const ctx = this.ctx;
-    const {r, g, b} = obj.color;
-    const {x, y} = obj.position;
-    const {x: vx, y: vy} = obj.velocity;
-    const acceleration = obj.acceleration;
-    const radius = obj.radius;
-    const {height: H, width: W} = this;
-    const ox = this.viewOrigin.x;
-    const oy = this.viewOrigin.y;
-    const cx = ox + W / 2;
-    const cy = oy + H / 2;
-
-    // Draw path traces
-    if (this.sim.getOption('display.traces') && obj.history?.length) {
-      const dashedTraces = this.sim.getOption('display.dashedTraces');
-      const opacity = dashedTraces ? PATH_TRACES_DASHED_OPACITY : PATH_TRACES_OPACITY;
-      ctx.strokeStyle = PATH_TRACES_COLOR === 'object color' ?
-        `rgba(${r}, ${g}, ${b}, ${opacity})` : PATH_TRACES_COLOR;
-      ctx.lineWidth = PATH_TRACES_WIDTH / this.scale;
-      ctx.beginPath();
-      let dash = false;
-      for (let i = 0; i < obj.history.length ; i++) {
-        // if (i % 2 > 0) continue;
-        const {position: {x, y}} = obj.history[i];
-        if (dashedTraces) {
-          if (dash) {
-            ctx.lineTo(x, y);
-          } else {
-            ctx.moveTo(x, y);
-          }
-          dash = !dash;
-        } else {
-          ctx.lineTo(x, y);
-        }
-      }
-      ctx.stroke();
-    }
-
-    if (!obj.alive) return;
-
-    // If the object is outside the display area, draw an arrow at the edge of the display
-    if (Math.abs(x - cx) - radius >= W / 2 ||
-      Math.abs(y - cy) - radius >= H / 2) {
-      // Find where a line from center of display to object intersects display edge
-      let px, py;
-      if (y <= cy) {
-        // Line intersects y = 0:
-        const y0px = cx + (H / 2) / (cy - y) * (x - cx);
-        if (Math.abs(y0px - cx) <= W / 2) {
-          px = y0px;
-          py = this.viewOrigin.y;
-        }
-      } else {
-        // Line intersects y = H
-        const yHpx = cx + (H / 2) / (y - cy) * (x - cx);
-        if (Math.abs(yHpx - cx) <= W / 2) {
-          px = yHpx;
-          py = this.viewOrigin.y + H;
-        }
-      }
-      if (px === undefined) {
-        if (x <= cx) {
-          // Line intersects x = 0:
-          px = this.viewOrigin.x;
-          py = cy + (W / 2) / (cx - x) * (y - cy);
-        } else {
-          // Line intersects x = W:
-          px = this.viewOrigin.x + W;
-          py = cy + (W / 2) / (x - cx) * (y - cy);
-        }
-      }
-
-      const arrowDirection = Math.atan2(py - cy, px - cx);
-      // Length of arrow based on distance (logarithmic scale)
-      const distance = Math.sqrt((x - px) ** 2, (y - py) ** 2) * this.scale;
-      const arrowLength = Math.log(distance) * OFFSCREEN_OBJECT_LINE_SCALE / this.scale;
-      const startAx = px - arrowLength * Math.cos(arrowDirection);
-      const startAy = py - arrowLength * Math.sin(arrowDirection);
-      this.drawArrow(startAx, startAy, px, py, {
-        style: `rgb(${r}, ${g}, ${b})`,
-        width: OFFSCREEN_OBJECT_LINE_WIDTH,
-        arrowheadLength: OFFSCREEN_OBJECT_ARROWHEAD_LENGTH,
-        fill: false,
-        ifShort: 'head',
-      });
-
-      return;
-    }
-
-    // Draw filled circle for the object
-    ctx.fillStyle = `rgb(${r}, ${g}, ${b})`;
-    ctx.beginPath();
-    ctx.arc(x, y, radius, 0, 2 * Math.PI);
-    ctx.fill();
-
-    // Draw arrow for the velocity
-    if (this.sim.getOption('display.velocity')) {
-      const speed = Math.sqrt(vx ** 2 + vy ** 2);
-      const endVx = x + VELOCITY_VECTOR_SCALE * vx / speed * Math.log(speed);
-      const endVy = y + VELOCITY_VECTOR_SCALE * vy / speed * Math.log(speed);
-      const style = VELOCITY_VECTOR_COLOR === 'object color' ?
-        `rgb(${r}, ${g}, ${b})` : VELOCITY_VECTOR_COLOR;
-      this.drawArrow(x, y, endVx, endVy, {
-        style,
-        width: VELOCITY_VECTOR_WIDTH,
-        arrowhead: VELOCITY_VECTOR_ARROWHEAD,
-        fill: false,
-        ifShort: 'head'
-      });
-    }
-
-    // Draw arrow for acceleration
-    if (this.sim.getOption('display.acceleration')) {
-      const accelerationMagnitude = Math.sqrt(acceleration.x ** 2 + acceleration.y ** 2);
-      const endAx = x + ACCELERATION_VECTOR_SCALE * acceleration.x /
-        accelerationMagnitude * Math.log(accelerationMagnitude);
-      const endAy = y + ACCELERATION_VECTOR_SCALE * acceleration.y /
-        accelerationMagnitude * Math.log(accelerationMagnitude);
-      const style = ACCELERATION_VECTOR_COLOR === 'object color' ?
-        `rgb(${r}, ${g}, ${b})` : ACCELERATION_VECTOR_COLOR;
-      this.drawArrow(x, y, endAx, endAy, {
-        style,
-        width: ACCELERATION_VECTOR_WIDTH,
-        arrowhead: ACCELERATION_VECTOR_ARROWHEAD,
-        fill: false,
-        ifShort: 'tail'
-      });
-    }
-  }
-
   drawObjects() {
-    this.sim.objects.forEachObject(obj => this.drawObject(obj), null);
+    this.sim.objects.forEachObject(obj => obj.drawObject(this.sim), null);
   }
 
   drawArrow(startX, startY, endX, endY, {style, width, arrowhead, arrowheadLength, fill, ifShort}) {

object.js

@@ -1,3 +1,21 @@
+import {
+  ACCELERATION_VECTOR_ARROWHEAD,
+  ACCELERATION_VECTOR_COLOR,
+  ACCELERATION_VECTOR_SCALE,
+  ACCELERATION_VECTOR_WIDTH,
+  OFFSCREEN_OBJECT_ARROWHEAD_LENGTH,
+  OFFSCREEN_OBJECT_LINE_SCALE,
+  OFFSCREEN_OBJECT_LINE_WIDTH,
+  PATH_TRACES_COLOR,
+  PATH_TRACES_DASHED_OPACITY,
+  PATH_TRACES_OPACITY,
+  PATH_TRACES_WIDTH,
+  VELOCITY_VECTOR_ARROWHEAD,
+  VELOCITY_VECTOR_COLOR,
+  VELOCITY_VECTOR_SCALE,
+  VELOCITY_VECTOR_WIDTH,
+} from './config.js';
+
 export class MassObject {
   mass = 0;
   density = 1;
@@ -25,7 +43,7 @@ export class MassObject {
 
   get radius() {
     // radius should be proportional to cube root of mass
-    return Math.pow(this.mass / this.density, 1/3);
+    return Math.pow(this.mass / this.density, 1 / 3);
   }
 
   getAcceleration() {
@@ -40,5 +58,146 @@ export class MassObject {
       y: ay / this.mass,
     };
   }
+
+  drawObject(sim) {
+    const {
+      color: {r, g, b},
+      position: {x, y},
+      velocity: {x: vx, y: vy},
+      acceleration,
+      radius,
+    } = this;
+
+    const {
+      display: {
+      ctx,
+        height: H,
+        width: W,
+        viewOrigin: {x: ox, y: oy},
+      }
+    } = sim;
+
+    const cx = ox + W / 2;
+    const cy = oy + H / 2;
+
+    // Draw path traces
+    if (sim.getOption('display.traces') && this.history?.length) {
+      const dashedTraces = sim.getOption('display.dashedTraces');
+      const opacity = dashedTraces ? PATH_TRACES_DASHED_OPACITY : PATH_TRACES_OPACITY;
+      ctx.strokeStyle = PATH_TRACES_COLOR === 'object color' ?
+        `rgba(${r}, ${g}, ${b}, ${opacity})` : PATH_TRACES_COLOR;
+      ctx.lineWidth = PATH_TRACES_WIDTH / this.scale;
+      ctx.beginPath();
+      let dash = false;
+      for (let i = 0; i < this.history.length; i++) {
+        // if (i % 2 > 0) continue;
+        const {position: {x, y}} = this.history[i];
+        if (dashedTraces) {
+          if (dash) {
+            ctx.lineTo(x, y);
+          } else {
+            ctx.moveTo(x, y);
+          }
+          dash = !dash;
+        } else {
+          ctx.lineTo(x, y);
+        }
+      }
+      ctx.stroke();
+    }
+
+    if (!this.alive) return;
+
+    // If the object is outside the display area, draw an arrow at the edge of the display
+    if (Math.abs(x - cx) - radius >= W / 2 ||
+      Math.abs(y - cy) - radius >= H / 2) {
+      // Find where a line from center of display to object intersects display edge
+      let px, py;
+      if (y <= cy) {
+        // Line intersects y = 0:
+        const y0px = cx + (H / 2) / (cy - y) * (x - cx);
+        if (Math.abs(y0px - cx) <= W / 2) {
+          px = y0px;
+          py = oy;
+        }
+      } else {
+        // Line intersects y = H
+        const yHpx = cx + (H / 2) / (y - cy) * (x - cx);
+        if (Math.abs(yHpx - cx) <= W / 2) {
+          px = yHpx;
+          py = oy + H;
+        }
+      }
+      if (px === undefined) {
+        if (x <= cx) {
+          // Line intersects x = 0:
+          px = ox;
+          py = cy + (W / 2) / (cx - x) * (y - cy);
+        } else {
+          // Line intersects x = W:
+          px = ox + W;
+          py = cy + (W / 2) / (x - cx) * (y - cy);
+        }
+      }
+
+      const arrowDirection = Math.atan2(py - cy, px - cx);
+      // Length of arrow based on distance (logarithmic scale)
+      const distance = Math.sqrt((x - px) ** 2, (y - py) ** 2) * this.scale;
+      const arrowLength = Math.log(distance) * OFFSCREEN_OBJECT_LINE_SCALE / this.scale;
+      const startAx = px - arrowLength * Math.cos(arrowDirection);
+      const startAy = py - arrowLength * Math.sin(arrowDirection);
+      sim.display.drawArrow(startAx, startAy, px, py, {
+        style: `rgb(${r}, ${g}, ${b})`,
+        width: OFFSCREEN_OBJECT_LINE_WIDTH,
+        arrowheadLength: OFFSCREEN_OBJECT_ARROWHEAD_LENGTH,
+        fill: false,
+        ifShort: 'head',
+      });
+
+      return;
+    }
+
+    // Draw filled circle for the object
+    ctx.fillStyle = `rgb(${r}, ${g}, ${b})`;
+    ctx.beginPath();
+    ctx.arc(x, y, radius, 0, 2 * Math.PI);
+    ctx.fill();
+
+    // Draw arrow for the velocity
+    if (sim.getOption('display.velocity')) {
+      const speed = Math.sqrt(vx ** 2 + vy ** 2);
+      const endVx = x + VELOCITY_VECTOR_SCALE * vx / speed * Math.log(speed);
+      const endVy = y + VELOCITY_VECTOR_SCALE * vy / speed * Math.log(speed);
+      const style = VELOCITY_VECTOR_COLOR === 'object color' ?
+        `rgb(${r}, ${g}, ${b})` : VELOCITY_VECTOR_COLOR;
+      sim.display.drawArrow(x, y, endVx, endVy, {
+        style,
+        width: VELOCITY_VECTOR_WIDTH,
+        arrowhead: VELOCITY_VECTOR_ARROWHEAD,
+        fill: false,
+        ifShort: 'head'
+      });
+    }
+
+    // Draw arrow for acceleration
+    if (sim.getOption('display.acceleration')) {
+      const accelerationMagnitude = Math.sqrt(acceleration.x ** 2 + acceleration.y ** 2);
+      const endAx = x + ACCELERATION_VECTOR_SCALE * acceleration.x /
+        accelerationMagnitude * Math.log(accelerationMagnitude);
+      const endAy = y + ACCELERATION_VECTOR_SCALE * acceleration.y /
+        accelerationMagnitude * Math.log(accelerationMagnitude);
+      const style = ACCELERATION_VECTOR_COLOR === 'object color' ?
+        `rgb(${r}, ${g}, ${b})` : ACCELERATION_VECTOR_COLOR;
+      sim.display.drawArrow(x, y, endAx, endAy, {
+        style,
+        width: ACCELERATION_VECTOR_WIDTH,
+        arrowhead: ACCELERATION_VECTOR_ARROWHEAD,
+        fill: false,
+        ifShort: 'tail'
+      });
+    }
+
+  }
+
 }
 

tool/play-pause.js

@@ -4,7 +4,11 @@ import {Tool} from '../tool.js';
 export class PlayPause extends Tool {
   playHTML = 'Play';
   pauseHTML = 'Pause';
+  clearTracesText = 'Clear Traces';
   currentTimeEl = undefined;
+  pauseButton = undefined;
+  playButton = undefined;
+  clearTracesEl = undefined;
 
   get timeText() {
     let time = this.sim.time;
@@ -36,52 +40,59 @@ export class PlayPause extends Tool {
     }
   }
 
+  updateButtons() {
+    this.pauseButton.style.opacity = this.sim.playing ? '100%' : '50%';
+    this.playButton.style.opacity = this.sim.playing ? '50%' : '100%';
+  }
+
   constructor(toolbar) {
     super(toolbar);
 
     const currentTime = document.createElement('button');
     const pauseButton = document.createElement('button');
     const playButton = document.createElement('button');
+    const clearTraces = document.createElement('button');
+    this.pauseButton = pauseButton;
+    this.playButton = playButton;
+    this.clearTracesEl = clearTraces;
     this.currentTimeEl = currentTime;
 
     this.div.appendChild(currentTime);
     this.div.appendChild(pauseButton);
     this.div.appendChild(playButton);
+    this.div.appendChild(clearTraces);
 
     currentTime.classList.add(TOOL_INFO_CLASSNAME);
     currentTime.classList.add(WIDE_CLASSNAME);
+    clearTraces.classList.add(WIDE_CLASSNAME);
 
     pauseButton.innerHTML = this.pauseHTML;
     playButton.innerHTML = this.playHTML;
     currentTime.innerHTML = this.timeText;
+    clearTraces.innerHTML = this.clearTracesText;
 
-    pauseButton.style.opacity = this.sim.playing ? '100%' : '50%';
+    this.updateButtons();
-    playButton.style.opacity = this.sim.playing ? '50%' : '100%';
 
-    pauseButton.addEventListener('click', (e) => {
+    pauseButton.addEventListener('click', () => {
-      e.stopPropagation();
       this.sim.pointer.panning = undefined;
-      if (this.playing) {
+      if (this.sim.playing) {
-        this.playing = false;
+        this.sim.playing = false;
-        pauseButton.style.opacity = '50%';
+        this.updateButtons();
-        playButton.style.opacity = '100%';
       }
     });
 
     playButton.addEventListener('click', () => {
-      if (!this.playing) {
+      if (!this.sim.playing) {
-        this.playing = true;
+        this.sim.playing = true;
-        pauseButton.style.opacity = '100%';
+        this.updateButtons();
-        playButton.style.opacity = '50%';
       }
     });
-  }
 
-  get playing() {
+    clearTraces.addEventListener('click', () => {
-    return this.sim.playing;
+      // Obliterate object histories
-  }
+      this.sim.objects.forEachObject(obj => {
-
+        obj.history = [];
-  set playing(playing) {
+      }, null);
-    this.sim.playing = playing;
+    });
   }
 }