fix #2671 - fix transform on 'scattergl' traces

- by mapping 'selectedpoints' input their post-transform values,
  using trace._indexToPoints
- by clearing 'dirty' flag after 1st of 2 _module.calc call,
  so that 2nd _module.calc does not append phony batches to
  scene render queue.

Author: etpinard

src/lib/index.js

@@ -478,6 +478,17 @@ lib.extractOption = function(calcPt, trace, calcKey, traceKey) {
     if(!Array.isArray(traceVal)) return traceVal;
 };
 
+function makePtIndex2PtNumber(indexToPoints) {
+    var ptIndex2ptNumber = {};
+    for(var k in indexToPoints) {
+        var pts = indexToPoints[k];
+        for(var j = 0; j < pts.length; j++) {
+            ptIndex2ptNumber[pts[j]] = +k;
+        }
+    }
+    return ptIndex2ptNumber;
+}
+
 /** Tag selected calcdata items
  *
  * N.B. note that point 'index' corresponds to input data array index
@@ -498,13 +509,7 @@ lib.tagSelected = function(calcTrace, trace, ptNumber2cdIndex) {
 
     // make pt index-to-number map object, which takes care of transformed traces
     if(indexToPoints) {
-        ptIndex2ptNumber = {};
-        for(var k in indexToPoints) {
-            var pts = indexToPoints[k];
-            for(var j = 0; j < pts.length; j++) {
-                ptIndex2ptNumber[pts[j]] = k;
-            }
-        }
+        ptIndex2ptNumber = makePtIndex2PtNumber(indexToPoints);
     }
 
     function isCdIndexValid(v) {
@@ -525,6 +530,30 @@ lib.tagSelected = function(calcTrace, trace, ptNumber2cdIndex) {
     }
 };
 
+lib.selIndices2selPoints = function(trace) {
+    var selectedpoints = trace.selectedpoints;
+    var indexToPoints = trace._indexToPoints;
+
+    if(indexToPoints) {
+        var ptIndex2ptNumber = makePtIndex2PtNumber(indexToPoints);
+        var out = [];
+
+        for(var i = 0; i < selectedpoints.length; i++) {
+            var ptIndex = selectedpoints[i];
+            if(lib.isIndex(ptIndex)) {
+                var ptNumber = ptIndex2ptNumber[ptIndex];
+                if(lib.isIndex(ptNumber)) {
+                    out.push(ptNumber);
+                }
+            }
+        }
+
+        return out;
+    } else {
+        return selectedpoints;
+    }
+};
+
 /** Returns target as set by 'target' transform attribute
  *
  * @param {object} trace : full trace object

src/plots/plots.js

@@ -2342,7 +2342,15 @@ plots.doCalcdata = function(gd, traces) {
             // we need one round of trace module calc before
             // the calc transform to 'fill in' the categories list
             // used for example in the data-to-coordinate method
-            if(_module && _module.calc) _module.calc(gd, trace);
+            if(_module && _module.calc) {
+                var cdi = _module.calc(gd, trace);
+
+                // must clear scene 'batches', so that 2nd
+                // _module.calc call starts from scratch
+                if(cdi[0] && cdi[0].t && cdi[0].t._scene) {
+                    delete cdi[0].t._scene.dirty;
+                }
+            }
 
             for(j = 0; j < trace.transforms.length; j++) {
                 var transform = trace.transforms[j];

src/traces/scattergl/index.js

@@ -492,12 +492,11 @@ function plot(gd, subplot, cdata) {
 
             // regenerate scene batch, if traces number changed during selection
             if(trace.selectedpoints) {
-                scene.selectBatch[id] = trace.selectedpoints;
+                var selPts = scene.selectBatch[id] = Lib.selIndices2selPoints(trace);
 
-                var selPts = trace.selectedpoints;
                 var selDict = {};
                 for(i = 0; i < selPts.length; i++) {
-                    selDict[selPts[i]] = true;
+                    selDict[selPts[i]] = 1;
                 }
                 var unselPts = [];
                 for(i = 0; i < stash.count; i++) {