fix recenter pointer zoom

build/escher.js

@@ -2429,14 +2429,28 @@
 	 */
 	ViewportControls.prototype.update = function(pointer)
 	{	
-		// Scale
-		if(this.allowScale && pointer.wheel !== 0)
-		{
-			var scale = pointer.wheel * 1e-3 * this.viewport.scale;
-
-			this.viewport.scale -= scale;
-			this.viewport.matrixNeedsUpdate = true;
-		}
+	       // Scale
+	       if(this.allowScale && pointer.wheel !== 0)
+	       {
+	               // Compute the pointer position in world space before applying the new scale
+	               var pointerWorld = null;
+	               if(this.recenterViewport === ViewportControls.RECENTER_POINTER && pointer.canvas !== null)
+	               {
+	                       pointerWorld = this.viewport.inverseMatrix.transformPoint(pointer.position);
+	               }
+
+	               var scale = pointer.wheel * 1e-3 * this.viewport.scale;
+
+	               this.viewport.scale -= scale;
+	               this.viewport.matrixNeedsUpdate = true;
+
+	               // Recenter viewport on pointer only when zooming
+	               if(pointerWorld !== null)
+	               {
+	                       this.viewport.center.copy(pointerWorld);
+	                       this.viewport.matrixNeedsUpdate = true;
+	               }
+	       }
 
 		// Rotation
 		if(this.allowRotation && pointer.buttonPressed(this.rotateButton))
@@ -2472,22 +2486,14 @@
 			return;
 		}
 
-		// Center viewport on canvas
-		if (this.recenterViewport === ViewportControls.RECENTER_CANVAS) {
-			var centerWorld = new Vector2(pointer.canvas.width / 2.0, pointer.canvas.height / 2.0);
-			centerWorld = this.viewport.inverseMatrix.transformPoint(centerWorld);
-			
-			this.viewport.center.copy(centerWorld);
-			this.viewport.matrixNeedsUpdate = true;
-		} 
-		// Center viewport on pointer
-		else if(this.recenterViewport === ViewportControls.RECENTER_POINTER)
-		{
-			var pointerWorld = this.viewport.inverseMatrix.transformPoint(pointer.position);
+	       // Center viewport on canvas
+	       if (this.recenterViewport === ViewportControls.RECENTER_CANVAS) {
+	               var centerWorld = new Vector2(pointer.canvas.width / 2.0, pointer.canvas.height / 2.0);
+	               centerWorld = this.viewport.inverseMatrix.transformPoint(centerWorld);
 
-			this.viewport.center.copy(pointerWorld);
-			this.viewport.matrixNeedsUpdate = true;
-		}
+	               this.viewport.center.copy(centerWorld);
+	               this.viewport.matrixNeedsUpdate = true;
+	       }
 	};
 
 	/**

source/controls/ViewportControls.js

@@ -121,14 +121,28 @@ ViewportControls.RECENTER_POINTER = 2;
  */
 ViewportControls.prototype.update = function(pointer)
 {	
-	// Scale
-	if(this.allowScale && pointer.wheel !== 0)
-	{
-		var scale = pointer.wheel * 1e-3 * this.viewport.scale;
-
-		this.viewport.scale -= scale;
-		this.viewport.matrixNeedsUpdate = true;
-	}
+       // Scale
+       if(this.allowScale && pointer.wheel !== 0)
+       {
+               // Compute the pointer position in world space before applying the new scale
+               var pointerWorld = null;
+               if(this.recenterViewport === ViewportControls.RECENTER_POINTER && pointer.canvas !== null)
+               {
+                       pointerWorld = this.viewport.inverseMatrix.transformPoint(pointer.position);
+               }
+
+               var scale = pointer.wheel * 1e-3 * this.viewport.scale;
+
+               this.viewport.scale -= scale;
+               this.viewport.matrixNeedsUpdate = true;
+
+               // Recenter viewport on pointer only when zooming
+               if(pointerWorld !== null)
+               {
+                       this.viewport.center.copy(pointerWorld);
+                       this.viewport.matrixNeedsUpdate = true;
+               }
+       }
 
 	// Rotation
 	if(this.allowRotation && pointer.buttonPressed(this.rotateButton))
@@ -164,22 +178,14 @@ ViewportControls.prototype.update = function(pointer)
 		return;
 	}
 
-	// Center viewport on canvas
-	if (this.recenterViewport === ViewportControls.RECENTER_CANVAS) {
-		var centerWorld = new Vector2(pointer.canvas.width / 2.0, pointer.canvas.height / 2.0);
-		centerWorld = this.viewport.inverseMatrix.transformPoint(centerWorld);
-		
-		this.viewport.center.copy(centerWorld);
-		this.viewport.matrixNeedsUpdate = true;
-	} 
-	// Center viewport on pointer
-	else if(this.recenterViewport === ViewportControls.RECENTER_POINTER)
-	{
-		var pointerWorld = this.viewport.inverseMatrix.transformPoint(pointer.position);
+       // Center viewport on canvas
+       if (this.recenterViewport === ViewportControls.RECENTER_CANVAS) {
+               var centerWorld = new Vector2(pointer.canvas.width / 2.0, pointer.canvas.height / 2.0);
+               centerWorld = this.viewport.inverseMatrix.transformPoint(centerWorld);
 
-		this.viewport.center.copy(pointerWorld);
-		this.viewport.matrixNeedsUpdate = true;
-	}
+               this.viewport.center.copy(centerWorld);
+               this.viewport.matrixNeedsUpdate = true;
+       }
 };
 
 export {ViewportControls};