fixed display vectors

Readme.md

@@ -8,8 +8,7 @@ Uses `npm` for `eslint`.
 Screenshots
 -----------
 
-![A small body orbiting a pair of larger ones](./gravity-simulator-2.png "Gravity Simulator Screenshot 2")
-![A body orbiting a pair, all three of similar size](./gravity-simulator-3.png "Gravity Simulator Screenshot 3")
+![A binary pair orbiting a larger partner](./gravity-simulator-4.png "Gravity Simulator Screenshot 4")
 
 TODO
 ----
@@ -31,10 +30,7 @@ TODO
   - [ ] Undo "Clear Traces" Action
   - [ ] Undo "Reset
 - [ ] Time Control: Reverse Time
-- [x] Save to LocalStorage
 - [ ] Lossy Rescaling To Widen Zoom (Handling overflow/underflow)
 - [ ] Track farthest reaches, min/max in each dimension (x, y)
-- [x] Compute Net Angular Momentum
-- [ ] Display Net Angular Momentum
 - [ ] Calculate Work as FxD as measure of energy flux
   - [ ] Option to automatically slow time when energy flux is greater

object.js

@@ -180,22 +180,19 @@ export class MassObject {
       let velocity = {x: vx, y: vy};
       if (isSelected) {
         const pointerV = this.sim.pointer.latestVelocity;
-        const scale = this.sim.display.scale;
         // const panning = this.sim.panning?.velocity ?? {x: 0, y: 0};
         // velocity.x = vx + (pointerV.x + panning.x) * scale;
         // velocity.y = vy + (pointerV.y + panning.y) * scale;
-        velocity.x = vx + pointerV.x * scale;
-        velocity.y = vy + pointerV.y * scale;
+        velocity.x = vx + pointerV.x / this.sim.timeScale;
+        velocity.y = vy + pointerV.y / this.sim.timeScale;
       }
-      const speed = Math.sqrt(velocity.x ** 2, velocity.y ** 2);
+      const speed = Math.sqrt(velocity.x ** 2, velocity.y ** 2) / this.sim.display.scale;
       const arrowDirection = Math.atan2(velocity.y, velocity.x);
       // Prevent negative numbers by adding 1
-      const arrowLength = Math.log(speed + 1) * vecScale;
+      // TODO: Make logarithmic vector length scale optional
+      const arrowLength = Math.log10(speed + 1) * vecScale + radius;
       const endVx = x + arrowLength * Math.cos(arrowDirection);
       const endVy = y + arrowLength * Math.sin(arrowDirection);
-      if (sim.getOption('debug.panningInfo')) {
-        console.log('velocity', {vecScale, isSelected, velocity, speed, arrowDirection, arrowLength, endVx, endVy});
-      }
       const style = VELOCITY_VECTOR_COLOR === 'object color' ?
         `rgb(${r}, ${g}, ${b})` : VELOCITY_VECTOR_COLOR;
       sim.display.drawArrow(x, y, endVx, endVy, {
@@ -209,11 +206,13 @@ export class MassObject {
 
     // Draw arrow for acceleration
     if (sim.getOption('display.acceleration')) {
-      const vecScale = this.sim.getOption('param.accelerationScale');
-      const accelerationMagnitude = Math.sqrt(acceleration.x ** 2 + acceleration.y ** 2);
+      const vecScale = this.sim.getOption('display.accelerationScale');
+      const accelerationMagnitude = Math.sqrt(acceleration.x ** 2 + acceleration.y ** 2) /
+        this.sim.display.scale;
       const arrowDirection = Math.atan2(acceleration.y, acceleration.x);
-      // Prevent negative numbers by adding e
-      const arrowLength = Math.log(accelerationMagnitude + 1) * vecScale / this.sim.display.scale;
+      // Prevent negative numbers by adding 1
+      const arrowLength = Math.log10(accelerationMagnitude + 1) * vecScale + radius;
+      //const arrowLength = accelerationMagnitude * vecScale;
       const endAx = x + arrowLength * Math.cos(arrowDirection);
       const endAy = y + arrowLength * Math.sin(arrowDirection);
       const style = ACCELERATION_VECTOR_COLOR === 'object color' ?

sim-options.js

@@ -4,12 +4,12 @@ export const simOptions = {
     selection: ['Pause While Selecting', 'boolean', true],
   }, 
   display: {
-    traces: ['Path Trace', 'boolean', true],
+    traces: ['Path Traces', 'boolean', true],
     dashedTraces: ['Dashed', 'boolean', false, {tall: true}],
-    velocity: ['Velocity Vector', 'boolean', true],
-    acceleration: ['Accel Vector', 'boolean', true],
-    velocityScale: ['Velocity<br>Vec Scale', 'number', 20],
-    accelerationScale: ['Accel<br>Vec Scale', 'number', 20],
+    velocity: ['Velocity Vectors', 'boolean', true],
+    acceleration: ['Accel Vectors', 'boolean', true],
+    velocityScale: ['Velocity<br>Vec Scale', 'number', 80],
+    accelerationScale: ['Accel<br>Vec Scale', 'number', 800],
   },
   collision: {
     merge: ['Merge Masses<br>on Collision', 'boolean', true, {wide: true}],
@@ -18,7 +18,6 @@ export const simOptions = {
     gravity: ['Gravity', 'number', 1],
     timeScale: ['Time Scale', 'number', 0.1],
     massCreationRate: ['Mass Creation Rate', 'number', 1],
-    massAcceleration: ['Mass Rate Accel', 'boolean', false, {wide: true}],
   },
   debug: {
     objectsInfo: ['Objects Info', 'boolean', false],

system.js

@@ -157,8 +157,8 @@ export class System {
     // Convert pointer velocity to simulation scale
     // Including time scale - if time is slow, our motion is relatively faster
     const pointer = {...this.sim.pointer.latestVelocity};
-    obj.velocity.x = pointer.x / this.sim.display.scale;
-    obj.velocity.y = pointer.y / this.sim.display.scale;
+    obj.velocity.x = pointer.x / this.sim.display.scale / this.sim.timeScale;
+    obj.velocity.y = pointer.y / this.sim.display.scale / this.sim.timeScale;
     if (this.sim.panning?.velocity) {
       obj.velocity.x += this.sim.panning.velocity.x;
       obj.velocity.y += this.sim.panning.velocity.y;
@@ -239,12 +239,7 @@ export class System {
 
     if (this.creatingObject !== undefined) {
       const obj = this.objects[this.creatingObject];
-      let massCreationRate = this.sim.getOption('param.massCreationRate');
-      // Mass creation rate acceleration
-      if (this.sim.getOption('param.massAcceleration')) {
-        // TODO: Separate parameter for mass creation acceleration rate
-        massCreationRate *= obj.rawAge;
-      }
+      let massCreationRate = this.sim.getOption('param.massCreationRate') / this.sim.display.scale;
       // Keep consistent time scale
       obj.mass += massCreationRate * elapsedTime / this.sim.timeScale;
     }

tool/utility.js

@@ -39,7 +39,6 @@ export class UtilityTool extends Tool {
   constructor(container) {
     super(container);
 
-    const zeroVelocity = document.createElement('button');
     const clearTraces = document.createElement('button');
     const currentTime = document.createElement('button');
     const clearDebug = document.createElement('button');
@@ -47,39 +46,18 @@ export class UtilityTool extends Tool {
     this.currentTimeEl = currentTime;
 
     this.div.appendChild(currentTime);
-    this.div.appendChild(zeroVelocity);
     this.div.appendChild(clearTraces);
     this.div.appendChild(clearDebug);
 
-    zeroVelocity.classList.add(WIDE_CLASSNAME);
     clearTraces.classList.add(WIDE_CLASSNAME);
     currentTime.classList.add(TOOL_INFO_CLASSNAME);
     currentTime.classList.add(WIDE_CLASSNAME);
     clearDebug.classList.add(WIDE_CLASSNAME);
 
-    zeroVelocity.innerHTML = 'Zero Momentum';
     clearTraces.innerHTML = 'Clear Traces';
     currentTime.innerHTML = this.timeText;
     clearDebug.innerHTML = 'Clear Debug';
 
-    zeroVelocity.addEventListener('click', () => {
-      // Determine center of mass and average momentum
-      const { totalMass, netMomentum } = this.sim.system.computeSystemCenter();
-      const netVelocity = {
-        x: netMomentum.x / totalMass,
-        y: netMomentum.y / totalMass,
-      };
-
-      // Apply offset to all object velocities
-      this.sim.system.forEachObject(obj => {
-        obj.velocity.x -= netVelocity.x;
-        obj.velocity.y -= netVelocity.y;
-      });
-
-      // Cancel panning
-      this.sim.panning = undefined;
-    });
-
     clearTraces.addEventListener('click', () => {
       // Obliterate object histories
       this.sim.system.forEachObject(obj => {

tool/zoom.js

@@ -3,7 +3,6 @@ import {
   ZOOM_IN_FACTOR,
   ZOOM_OUT_FACTOR,
   WIDE_CLASSNAME,
-  TALL_CLASSNAME,
   TOOL_INFO_CLASSNAME,
 } from '../config.js';
 
@@ -19,21 +18,22 @@ export class Zoom extends Tool {
     const zoomOut = document.createElement('button');
     const zoomIn = document.createElement('button');
     const zoomAll = document.createElement('button');
+    const zeroVelocity = document.createElement('button');
 
     this.div.appendChild(currentScale);
     this.div.appendChild(zoomOut);
     this.div.appendChild(zoomIn);
     this.div.appendChild(zoomAll);
+    this.div.appendChild(zeroVelocity);
 
     currentScale.classList.add(WIDE_CLASSNAME);
     currentScale.classList.add(TOOL_INFO_CLASSNAME);
-    zoomAll.classList.add(WIDE_CLASSNAME);
-    zoomAll.classList.add(TALL_CLASSNAME);
 
     currentScale.innerHTML = this.displayScaleText;
     zoomOut.innerHTML = 'Zoom<br>Out';
     zoomIn.innerHTML = 'Zoom<br>In';
     zoomAll.innerHTML = 'Zoom to Fit';
+    zeroVelocity.innerHTML = 'Zero Momentum';
 
     this.sim.onZoom(() => {
       currentScale.innerHTML = this.displayScaleText;
@@ -60,7 +60,7 @@ export class Zoom extends Tool {
       const y = (box.start.y + box.end.y) / 2;
       const widthRatio = Math.abs(box.start.x - box.end.x) / this.sim.display.width;
       const heightRatio = Math.abs(box.start.y - box.end.y) / this.sim.display.height;
-      const ratio = Math.max(widthRatio, heightRatio) * 2.5;
+      const ratio = Math.max(widthRatio, heightRatio) * 4;
       const factor = Math.ceil(Math.log2(1 / ratio));
 
       // Determine average momentum and set panning velocity to match
@@ -71,5 +71,24 @@ export class Zoom extends Tool {
       };
       this.sim.scheduleZoom({x, y}, factor, netVelocity)
     });
+
+    zeroVelocity.addEventListener('click', () => {
+      // Determine center of mass and average momentum
+      const { totalMass, netMomentum } = this.sim.system.computeSystemCenter();
+      const netVelocity = {
+        x: netMomentum.x / totalMass,
+        y: netMomentum.y / totalMass,
+      };
+
+      // Apply offset to all object velocities
+      this.sim.system.forEachObject(obj => {
+        obj.velocity.x -= netVelocity.x;
+        obj.velocity.y -= netVelocity.y;
+      });
+
+      // Cancel panning
+      this.sim.panning = undefined;
+    });
+
   }
 }