From 0a9c26f471cf2df104f1567d5de3b85394e071a9 Mon Sep 17 00:00:00 2001
From: Joel Ostblom <joel.ostblom@gmail.com>
Date: Sat, 11 Nov 2023 11:15:37 -0800
Subject: [PATCH] Add explicit option to control how densities are resolved

---
 src/compile/data/density.ts | 4 +---
 src/transform.ts            | 8 ++++++++
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/src/compile/data/density.ts b/src/compile/data/density.ts
index 6b4317dc50..68ad8018fc 100644
--- a/src/compile/data/density.ts
+++ b/src/compile/data/density.ts
@@ -40,9 +40,7 @@ export class DensityTransformNode extends DataFlowNode {
       field: density,
       ...rest
     };
-    if (this.transform.groupby) {
-      result.resolve = 'shared';
-    }
+    result.resolve = this.transform.resolve;
     return result;
   }
 }
diff --git a/src/transform.ts b/src/transform.ts
index 33b10bb723..d6d6e2d890 100644
--- a/src/transform.ts
+++ b/src/transform.ts
@@ -496,6 +496,14 @@ export interface DensityTransform {
    * __Default value:__ `["value", "density"]`
    */
   as?: [FieldName, FieldName];
+  /**
+   * Indicates how parameters for multiple densities should be resolved.
+   * If "independent", each density may have its own domain extent and dynamic number of curve sample steps.
+   * If "shared", the KDE transform will ensure that all densities are defined over a shared domain and curve steps, enabling stacking.
+   *
+   * __Default value:__ `"independent"`
+   */
+  resolve?: 'independent' | 'shared';
 }
 
 export function isDensity(t: Transform): t is DensityTransform {