do not attempt to cluster scattergl data < 1e5 pts

- note that to do so for 1e4 < pts < 1e5, we must set
  the regl-scatter2d "snap" option too 1e5 (aka TOO_MANY_POINTS)
  as regl-scatter2d uses a dflt value of 1e4.

Author: etpinard

src/traces/scattergl/index.js

@@ -43,6 +43,7 @@ function calc(gd, trace) {
     var ya = AxisIDs.getFromId(gd, trace.yaxis);
     var subplot = fullLayout._plots[trace.xaxis + trace.yaxis];
     var len = trace._length;
+    var hasTooManyPoints = len >= TOO_MANY_POINTS;
     var len2 = len * 2;
     var stash = {};
     var i, xx, yy;
@@ -73,7 +74,7 @@ function calc(gd, trace) {
 
     // we don't build a tree for log axes since it takes long to convert log2px
     // and it is also
-    if(xa.type !== 'log' && ya.type !== 'log') {
+    if(hasTooManyPoints && (xa.type !== 'log' && ya.type !== 'log')) {
         // FIXME: delegate this to webworker
         stash.tree = cluster(positions);
     } else {
@@ -93,7 +94,7 @@ function calc(gd, trace) {
     // use average marker size instead to speed things up.
     setFirstScatter(fullLayout, trace);
     var ppad;
-    if(len < TOO_MANY_POINTS) {
+    if(!hasTooManyPoints) {
         ppad = calcMarkerSize(trace, len);
     } else if(opts.marker) {
         ppad = 2 * (opts.marker.sizeAvg || Math.max(opts.marker.size, 3));
@@ -111,8 +112,8 @@ function calc(gd, trace) {
 
     // FIXME: organize it in a more appropriate manner, probably in sceneOptions
     // put point-cluster instance for optimized regl calc
-    if(opts.marker && len >= TOO_MANY_POINTS) {
-        opts.marker.cluster = stash.tree;
+    if(opts.marker) {
+        opts.marker.snap = stash.tree || TOO_MANY_POINTS;
     }
 
     // save scene opts batch