Index: ../trunk-jpl/src/m/plot/webgl.js
===================================================================
--- ../trunk-jpl/src/m/plot/webgl.js	(revision 20484)
+++ ../trunk-jpl/src/m/plot/webgl.js	(revision 20485)
@@ -341,7 +341,7 @@
 		canvas.rotation[1] += degrees((canvas.lastDeltaY - ev.deltaY) / canvas.clientHeight / canvas.zoomFactor * -2);
 		
 		if (canvas.rotation[0] > 360) {canvas.rotation[0] -= 360};
-		if (canvas.rotation[0] < 0) {canvas.rotation[0] += 360};
+		if (canvas.rotation[0] < -360) {canvas.rotation[0] += 360};
 		if (canvas.rotation[1] > 180) {canvas.rotation[1] -= 360};
 		if (canvas.rotation[1] < -180) {canvas.rotation[1] += 360};