add 'anchor' to mimic gl-cone3d's coneOffset

Author: etpinard

package-lock.json

@@ -70,7 +70,7 @@
     "es6-promise": "^3.0.2",
     "fast-isnumeric": "^1.1.1",
     "font-atlas-sdf": "^1.3.3",
-    "gl-cone3d": "git@github.com:gl-vis/gl-cone3d#c675b25e5991e63d0ad23ed24d712c496c28cd72",
+    "gl-cone3d": "git@github.com:gl-vis/gl-cone3d#cc6c768d844d0c7ad7dc4dd0d2cdd71eadf92620",
     "gl-contour2d": "^1.1.4",
     "gl-error3d": "^1.0.7",
     "gl-heatmap2d": "^1.0.4",

package.json

@@ -103,6 +103,19 @@ var attrs = {
         description: 'Sets the cone size reference value.'
     },
 
+    anchor: {
+        valType: 'enumerated',
+        role: 'info',
+        editType: 'calc',
+        values: ['tip', 'tail', 'cm', 'center'],
+        dflt: 'cm',
+        description: [
+            'Sets the cones\' anchor with respect to their x/y/z positions.',
+            'Note that *cm* denote the cone\'s center of mass with corresponds to',
+            '1/4 from the tail to tip.'
+        ].join(' ')
+    },
+
     text: {
         valType: 'string',
         role: 'info',

src/traces/cone/attributes.js

@@ -56,6 +56,7 @@ function zip3(x, y, z) {
 
 var axisName2scaleIndex = {xaxis: 0, yaxis: 1, zaxis: 2};
 var sizeMode2sizeKey = {scaled: 'coneSize', absolute: 'absoluteConeSize'};
+var anchor2coneOffset = {tip: 1, tail: 0, cm: 0.25, center: 0.5};
 
 function convert(scene, trace) {
     var sceneLayout = scene.fullSceneLayout;
@@ -92,6 +93,7 @@ function convert(scene, trace) {
     coneOpts.vertexIntensityBounds = [trace.cmin / trace.cmax, 1];
 
     coneOpts[sizeMode2sizeKey[trace.sizemode]] = trace.sizeref;
+    coneOpts.coneOffset = anchor2coneOffset[trace.anchor];
 
     var meshOpts = conePlot(coneOpts);
     meshOpts._pts = coneOpts.positions;

src/traces/cone/convert.js

@@ -42,6 +42,8 @@ module.exports = function supplyDefaults(traceIn, traceOut, defaultColor, layout
     coerce('sizeref');
     coerce('sizemode');
 
+    coerce('anchor');
+
     // TODO do these attributes work?
     coerce('lighting.ambient');
     coerce('lighting.diffuse');

src/traces/cone/defaults.js

@@ -9,7 +9,8 @@
       "v": [0, 3, 0],
       "w": [0, 0, 2],
       "sizemode": "absolute",
-      "sizeref": 2
+      "sizeref": 2,
+      "anchor": "tip"
     },
     {
       "type": "cone",