[core] Support fill-extrusion-vertical-gradient

2 files changed, 52 insertions, 0 deletions

diff --git a/platform/darwin/src/MGLFillExtrusionStyleLayer.h b/platform/darwin/src/MGLFillExtrusionStyleLayer.h
index 6e807c1b44..98eb6b3c20 100644
--- a/platform/darwin/src/MGLFillExtrusionStyleLayer.h
+++ b/platform/darwin/src/MGLFillExtrusionStyleLayer.h
@@ -164,6 +164,33 @@ MGL_EXPORT
 @property (nonatomic) MGLTransition fillExtrusionColorTransition;
 
 /**
+ Whether to apply a vertical gradient to the sides of a fill-extrusion layer. If
+ true, sides will be shaded slightly darker farther down.
+ 
+ The default value of this property is an expression that evaluates to `YES`.
+ Set this property to `nil` to reset it to the default value.
+ 
+ This attribute corresponds to the <a
+ href="https://www.mapbox.com/mapbox-gl-style-spec/#paint-fill-extrusion-vertical-gradient"><code>fill-extrusion-vertical-gradient</code></a>
+ layout property in the Mapbox Style Specification.
+ 
+ You can set this property to an expression containing any of the following:
+ 
+ * Constant Boolean values
+ * Predefined functions, including mathematical and string operators
+ * Conditional expressions
+ * Variable assignments and references to assigned variables
+ * Step functions applied to the `$zoomLevel` variable
+ 
+ This property does not support applying interpolation functions to the
+ `$zoomLevel` variable or applying interpolation or step functions to feature
+ attributes.
+ */
+@property (nonatomic, null_resettable) NSExpression *fillExtrusionHasVerticalGradient;
+
+@property (nonatomic, null_resettable) NSExpression *fillExtrusionVerticalGradient __attribute__((unavailable("Use fillExtrusionHasVerticalGradient instead.")));
+
+/**
  The height with which to extrude this layer.
  
  This property is measured in meters.
diff --git a/platform/darwin/src/MGLFillExtrusionStyleLayer.mm b/platform/darwin/src/MGLFillExtrusionStyleLayer.mm
index 03676a4ed5..e4e9c707ea 100644
--- a/platform/darwin/src/MGLFillExtrusionStyleLayer.mm
+++ b/platform/darwin/src/MGLFillExtrusionStyleLayer.mm
@@ -156,6 +156,31 @@ namespace mbgl {
     return transition;
 }
 
+- (void)setFillExtrusionHasVerticalGradient:(NSExpression *)fillExtrusionHasVerticalGradient {
+    MGLAssertStyleLayerIsValid();
+    MGLLogDebug(@"Setting fillExtrusionHasVerticalGradient: %@", fillExtrusionHasVerticalGradient);
+
+    auto mbglValue = MGLStyleValueTransformer<bool, NSNumber *>().toPropertyValue<mbgl::style::PropertyValue<bool>>(fillExtrusionHasVerticalGradient, false);
+    self.rawLayer->setFillExtrusionVerticalGradient(mbglValue);
+}
+
+- (NSExpression *)fillExtrusionHasVerticalGradient {
+    MGLAssertStyleLayerIsValid();
+
+    auto propertyValue = self.rawLayer->getFillExtrusionVerticalGradient();
+    if (propertyValue.isUndefined()) {
+        propertyValue = self.rawLayer->getDefaultFillExtrusionVerticalGradient();
+    }
+    return MGLStyleValueTransformer<bool, NSNumber *>().toExpression(propertyValue);
+}
+
+- (void)setFillExtrusionVerticalGradient:(NSExpression *)fillExtrusionVerticalGradient {
+}
+
+- (NSExpression *)fillExtrusionVerticalGradient {
+    return self.fillExtrusionHasVerticalGradient;
+}
+
 - (void)setFillExtrusionHeight:(NSExpression *)fillExtrusionHeight {
     MGLAssertStyleLayerIsValid();
     MGLLogDebug(@"Setting fillExtrusionHeight: %@", fillExtrusionHeight);