make modHalf restrict output to "half" of Math.abs(input)

- and use it in Lib.angleDelta

Author: etpinard

src/lib/angles.js

@@ -8,7 +8,9 @@
 
 'use strict';
 
-var mod = require('./mod').mod;
+var modModule = require('./mod');
+var mod = modModule.mod;
+var modHalf = modModule.modHalf;
 
 var PI = Math.PI;
 var twoPI = 2 * PI;
@@ -37,7 +39,7 @@ function isFullCircle(aBnds) {
  * @return {number} angular delta in *radians*
  */
 function angleDelta(a, b) {
-    return mod((b - a) - PI, twoPI) - PI;
+    return modHalf(b - a, twoPI);
 }
 
 /**

src/lib/coerce.js

@@ -186,7 +186,7 @@ exports.valObjectMeta = {
         coerceFunction: function(v, propOut, dflt) {
             if(v === 'auto') propOut.set('auto');
             else if(!isNumeric(v)) propOut.set(dflt);
-            else propOut.set(modHalf(+v, 180));
+            else propOut.set(modHalf(+v, 360));
         }
     },
     subplotid: {

src/lib/mod.js

@@ -22,9 +22,8 @@ function mod(v, d) {
  * rather than (-d, 0] if v is negative
  */
 function modHalf(v, d) {
-    var d2 = 2 * d;
-    return Math.abs(v) > d ?
-        v - Math.round(v / d2) * d2 :
+    return Math.abs(v) > (d / 2) ?
+        v - Math.round(v / d) * d :
         v;
 }
 

src/plots/polar/polar.js

@@ -1121,7 +1121,7 @@ proto.updateAngularDrag = function(fullLayout) {
         });
 
         // update rotation -> range -> _m,_b
-        angularAxis.rotation = Lib.modHalf(rot1, 180);
+        angularAxis.rotation = Lib.modHalf(rot1, 360);
         angularAxis.setGeometry();
         angularAxis.setScale();
 

src/traces/scattermapbox/hover.js

@@ -35,7 +35,7 @@ module.exports = function hoverPoints(pointData, xval, yval) {
         var lonlat = d.lonlat;
         if(lonlat[0] === BADNUM) return Infinity;
 
-        var lon = Lib.modHalf(lonlat[0], 180);
+        var lon = Lib.modHalf(lonlat[0], 360);
         var lat = lonlat[1];
         var pt = subplot.project([lon, lat]);
         var dx = pt.x - xa.c2p([xval2, lat]);
@@ -52,7 +52,7 @@ module.exports = function hoverPoints(pointData, xval, yval) {
 
     var di = cd[pointData.index];
     var lonlat = di.lonlat;
-    var lonlatShifted = [Lib.modHalf(lonlat[0], 180) + lonShift, lonlat[1]];
+    var lonlatShifted = [Lib.modHalf(lonlat[0], 360) + lonShift, lonlat[1]];
 
     // shift labels back to original winded globe
     var xc = xa.c2p(lonlatShifted);

src/traces/scattermapbox/select.js

@@ -32,7 +32,7 @@ module.exports = function selectPoints(searchInfo, polygon) {
             var lonlat = di.lonlat;
 
             if(lonlat[0] !== BADNUM) {
-                var lonlat2 = [Lib.modHalf(lonlat[0], 180), lonlat[1]];
+                var lonlat2 = [Lib.modHalf(lonlat[0], 360), lonlat[1]];
                 var xy = [xa.c2p(lonlat2), ya.c2p(lonlat2)];
 
                 if(polygon.contains(xy)) {