improved scaling representation and mode selection

config.js

@@ -1,8 +1,9 @@
 export const DISPLAY_OBJECTS_INFO = false;
 export const DISPLAY_CURSOR_INFO = false;
-export const DISPLAY_CANVAS_SIZE = true;
-
+export const DISPLAY_CANVAS_SIZE = false;
+export const DISPLAY_CURRENT_SCALE = true;
 export const DISPLAY_VELOCITY_VECTORS = true;
+
 export const MASS_CREATION_RATE = 0.001;
 export const POINTER_HISTORY_SIZE = 10;
 export const VELOCITY_VECTOR_SCALE = 0.2;
@@ -15,10 +16,11 @@ export const MOTION_TIME_SCALE = 0.001;
 export const OFFSCREEN_OBJECT_LINE_SCALE = 7;
 export const OFFSCREEN_OBJECT_LINE_WIDTH = 2;
 export const OFFSCREEN_OBJECT_ARROWHEAD_LENGTH = 15;
-export const ZOOM_IN_FACTOR = 2;
-export const ZOOM_OUT_FACTOR = 0.5;
-export const SCALE_MAX = 256;
-export const SCALE_MIN = 1/256;
+export const ZOOM_IN_FACTOR = 1;
+export const ZOOM_OUT_FACTOR = -1;
+export const SCALE_POWER_MAX = 8;
+export const SCALE_POWER_MIN = -8; 
+
 export const DRAGGABLE_ELEMENT_CLASSNAME = 'lhg-draggable-element';
 
 export const MODE_MASS_GENERATION = 'mass-gen';

display.js

@@ -13,7 +13,7 @@ import {
 
 export class Display {
   sim = undefined;
-  scale = 1;
+  scalePower = 0;
   viewOrigin = {x: 0, y: 0};
 
   constructor(sim) {
@@ -30,6 +30,10 @@ export class Display {
     window.addEventListener('resize', () => this.fullscreen());
   }
 
+  get scale() {
+    return 2 ** this.scalePower;
+  }
+
   get ctx() {
     const ctx = this.canvas.getContext("2d");
     ctx.resetTransform();

pointer.js

@@ -5,6 +5,7 @@ import {
   DISPLAY_CURSOR_INFO,
   DRAGGABLE_ELEMENT_CLASSNAME,
   MODE_MASS_GENERATION,
+  MODE_PAN_VIEW,
 } from './config.js';
 
 function dispatchEvent(target, eventType, data) {
@@ -17,6 +18,7 @@ export class Pointer {
 
   pointerHistory = [];
   draggingElement = undefined;
+  panning = undefined;
 
   constructor(sim) {
     this.sim = sim;
@@ -127,10 +129,16 @@ export class Pointer {
 
     if (this.sim.isCurrentMode(MODE_MASS_GENERATION)) {
       this.sim.objects.handlePointerDown({x, y});
+    } else if (this.sim.isCurrentMode(MODE_PAN_VIEW)) {
+      this.panning = {
+        pointerStart: {x, y},
+        pointerCurrent: {x, y},
+      };
     }
   }
 
   handlePointerUp({x, y}) {
+    this.panning = undefined;
     if (this.sim.isCurrentMode(MODE_MASS_GENERATION)) {
       this.sim.objects.handlePointerUp({x, y});
     }

simulator.js

@@ -6,7 +6,11 @@ import { Toolbar } from './toolbar.js';
 import { PlayPause } from './tool/play-pause.js';
 import { Zoom } from './tool/zoom.js';
 import { ModeSwitch } from './tool/modes.js';
-import { SCALE_MAX, SCALE_MIN} from './config.js';
+import { 
+  SCALE_POWER_MAX, 
+  SCALE_POWER_MIN,
+  DISPLAY_CURRENT_SCALE,
+} from './config.js';
 
 export class Sim {
   info = {};
@@ -53,9 +57,9 @@ export class Sim {
     // x, y are the mouse coordinates, which should be the center of the new view frame
     // the new view origin should be x, y minus half the new view width and height
     // compute new scale
-    this.display.scale = this.display.scale * factor;
-    if (this.display.scale > SCALE_MAX) this.display.scale = SCALE_MAX;
-    if (this.display.scale < SCALE_MIN) this.display.scale = SCALE_MIN;
+    this.display.scalePower += factor > 0 ? 1 : -1;
+    if (this.display.scalePower > SCALE_POWER_MAX) this.display.scalePower = SCALE_POWER_MAX;
+    if (this.display.scalePower < SCALE_POWER_MIN) this.display.scalePower = SCALE_POWER_MIN;
     // compute coordinates of new view frame
     this.display.viewOrigin.x = x - this.display.width / 2;
     this.display.viewOrigin.y = y - this.display.height / 2;
@@ -78,16 +82,27 @@ export class Sim {
   loop(currentTime) {
     const elapsedTime = currentTime - this.time;
     this.time = currentTime;
+
+    this.info['Mode'] = this.getCurrentMode();
+
     if (this.nextZoom) {
       this.zoom(this.nextZoom);
       this.nextZoom = undefined;
     }
-    this.info['scale'] = this.display.scale;
+
+    if (DISPLAY_CURRENT_SCALE) {
+      const scale = 2 ** Math.abs(this.display.scalePower);
+      this.info['Scale'] = this.display.scalePower >= 0 ?  `${scale}` : `1/${scale}`;
+    }
+
     this.objects.computeFrame(elapsedTime);
-    this.display.fillCanvas();
-    this.display.drawObjects();
+
     this.overlay.updateDraggable();
     this.overlay.renderInfo();
+
+    this.display.fillCanvas();
+    this.display.drawObjects();
+
     requestAnimationFrame(t => this.loop(t));
   }
 }

tool/modes.js

@@ -11,6 +11,7 @@ export class ModeSwitch extends Tool {
     [MODE_MASS_GENERATION, 'Generate Mass'],
     [MODE_PAN_VIEW, 'Pan View'],
   ];
+  buttons = [];
 
   constructor(toolbar) {
     super(toolbar);
@@ -34,21 +35,31 @@ export class ModeSwitch extends Tool {
 
     for (let [modeID, modeTitle] of this.modes) {
       const button = document.createElement('button');
+      this.buttons.push(button);
+      button.modeID = modeID;
       modesDiv.appendChild(button);
       button.innerHTML = `<h3>${modeTitle}</h3>`;
       button.classList.add('wide');
-      button.style.opacity = modeID === currentModeID ? '50%' : '100%';
 
       button.addEventListener('click', (e) => {
         if (this.currentMode !== modeID) {
           this.currentMode = modeID;
+          this.setModesOpacity();
         }
       });
     }
+    this.setModesOpacity();
 
     // Add global method to get current mode / check mode
     this.sim.getCurrentMode = () => this.currentMode;
     this.sim.isCurrentMode = (modeID) => modeID === this.currentMode;
   }
 
+  setModesOpacity() {
+    for (let button of this.buttons) {
+      button.style.opacity = button.modeID === this.currentMode ? '50%' : '100%';
+    }
+
+  }
+
 }