WIP: check if we can remove polar checks

Author: hydrosquall

src/stack.ts

@@ -1,6 +1,6 @@
 import {array, hasOwnProperty, isBoolean} from 'vega-util';
 import {Aggregate, SUM_OPS} from './aggregate.js';
-import {getSecondaryRangeChannel, NonPositionChannel, NONPOSITION_CHANNELS, isPolarPositionChannel} from './channel.js';
+import {getSecondaryRangeChannel, NonPositionChannel, NONPOSITION_CHANNELS} from './channel.js';
 import {
   channelDefType,
   FieldName,
@@ -178,11 +178,12 @@ export function stack(m: Mark | MarkDef, encoding: Encoding<string>): StackPrope
     const dimensionField = isFieldDef(dimensionDef) ? vgField(dimensionDef, {}) : undefined;
     const hasSameDimensionAndStackedField = dimensionField && dimensionField === stackedField;
 
-    // For polar coordinates, do not set a groupBy when working with quantitative fields.
-    const isPolar = isPolarPositionChannel(fieldChannel) || isPolarPositionChannel(dimensionChannel);
-    const shouldAddPolarGroupBy = !isUnbinnedQuantitative(dimensionDef);
+    // Do not set a groupBy when working with unbinned quantitative fields
+    // This applies to both polar and cartesian coordinates
+    const shouldAddGroupBy = !isUnbinnedQuantitative(dimensionDef);
 
-    if (isPolar ? shouldAddPolarGroupBy : !hasSameDimensionAndStackedField) {
+    // If it's binned, we don't need to group by the dimension field, because we will filter out the offset in the end anyway
+    if (shouldAddGroupBy && !hasSameDimensionAndStackedField) {
       // avoid grouping by the stacked field
       groupbyChannels.push(dimensionChannel);
       groupbyFields.add(dimensionField);