Remove angle attribute

Author: degzhaus

src/traces/quiver/attributes.js

@@ -65,14 +65,6 @@ var attrs = {
             'or *cm*/*center*/*middle* to center the arrow on (x,y).'
         ].join(' ')
     },
-    angle: {
-        valType: 'number',
-        dflt: Math.PI / 9,
-        min: 0,
-        max: Math.PI / 2,
-        editType: 'calc',
-        description: 'Angle of arrowhead in radians. Default = π/9'
-    },
     hoverdistance: {
         valType: 'number',
         min: -1,

src/traces/quiver/defaults.js

@@ -45,7 +45,6 @@ module.exports = function supplyDefaults(traceIn, traceOut, defaultColor, layout
     coerce('arrowsize', 1);
     // back-compat
     coerce('arrow_scale');
-    coerce('angle', Math.PI / 9);
     coerce('hoverdistance', 20);
 
     // Line styling

src/traces/quiver/plot.js

@@ -114,7 +114,10 @@ function plotOne(gd, idx, plotinfo, cdscatter, cdscatterAll, element, transition
         var arrowScale = (trace.arrowsize !== undefined)
             ? (baseHeadScale * trace.arrowsize)
             : (trace.arrow_scale !== undefined ? trace.arrow_scale : baseHeadScale);
-        var angle = trace.angle || Math.PI / 12; // small default
+        // Fixed arrowhead wedge angle (radians).
+        // Arrow direction is fully determined by u,v (see barbAng below);
+        // this constant only controls the opening of the head.
+        var headAngle = Math.PI / 12;
 
         var u = (trace.u && trace.u[cdi.i]) || 0;
         var v = (trace.v && trace.v[cdi.i]) || 0;
@@ -138,8 +141,8 @@ function plotOne(gd, idx, plotinfo, cdscatter, cdscatterAll, element, transition
         var arrowLen = barbLen * arrowScale;
         var barbAng = Math.atan2(dy, dx / scaleRatio);
 
-        var ang1 = barbAng + angle;
-        var ang2 = barbAng - angle;
+        var ang1 = barbAng + headAngle;
+        var ang2 = barbAng - headAngle;
 
         var x0, y0, x1, y1;
         if (anchor === 'tip') {