closes #1317

Author: Fil

src/marks/raster.js

@@ -95,10 +95,11 @@ export class Raster extends AbstractRaster {
   }
   // Ignore the color scale, so the fill channel is returned unscaled.
   scale(channels, {color, ...scales}, context) {
+    this.recolor = channels.fill?.scale;
     return super.scale(channels, scales, context);
   }
   render(index, scales, channels, dimensions, context) {
-    const color = scales.color ?? ((x) => x);
+    const color = this.recolor && scales.color ? scales.color : (x) => x;
     const {x: X, y: Y} = channels;
     const {document} = context;
     const [x1, y1, x2, y2] = renderBounds(channels, dimensions, context);

test/output/rasterVapor2.html

@@ -17,6 +17,25 @@ export async function rasterVapor() {
   });
 }
 
+export async function rasterVapor2() {
+  return Plot.plot({
+    color: {scheme: "blues", legend: true},
+    x: {transform: (x) => x - 180},
+    y: {transform: (y) => 90 - y},
+    marks: [
+      Plot.raster(await vapor(), {
+        width: 360,
+        height: 180
+      }),
+      Plot.raster(await vapor(), {
+        width: 360,
+        height: 180,
+        fill: {value: (d) => (d > 4 ? "red" : null), scale: null}
+      })
+    ]
+  });
+}
+
 export async function contourVapor() {
   return Plot.plot({
     width: 960,