issue #5090: updating anno view transform using map's current transfo…

…rm state

platform/ios/app/MBXViewController.m

@@ -1169,4 +1169,10 @@ - (void)mapView:(MGLMapView *)mapView tapOnCalloutForAnnotation:(id <MGLAnnotati
     point.coordinate = [self.mapView convertPoint:self.mapView.center toCoordinateFromView:self.mapView];
 }
 
+-(void)mapView:(MGLMapView *)mapView didSelectAnnotationView:(MGLAnnotationView *)annotationView
+{
+    annotationView.lockAxis = ( (int)annotationView.lockAxis + 1 ) % 4;
+    NSLog(@"lockAxis[%p]: 0x%x", annotationView, annotationView.lockAxis);
+}
+
 @end

platform/ios/src/MGLAnnotationView.h

@@ -36,6 +36,31 @@ typedef NS_ENUM(NSUInteger, MGLAnnotationViewDragState) {
     MGLAnnotationViewDragStateEnding,
 };
 
+/**
+   Options for locking the orientation of an `MGLAnnotationView` along one or more
+   axes for a billboard effect.
+ 
+   By default the billboard will always facing the view flat
+ */
+typedef NS_OPTIONS(NSUInteger, MGLAnnotationViewBillboardLocking) {
+
+    /**
+      Locking the tilting angle so it tilts with the map
+     */
+    MGLAnnotationViewBillboardLockingTilt = 0x01 << 0,
+
+    /**
+      Locking the heading angle so it rotates with the map
+     */
+    MGLAnnotationViewBillboardLockingHeading = 0x01 << 1,
+
+    /**
+      Billboard tilts and rotates with the map
+     */
+    MGLAnnotationViewBillboardLockingAll = MGLAnnotationViewBillboardLockingTilt |
+        MGLAnnotationViewBillboardLockingHeading
+};
+
 /**
  The `MGLAnnotationView` class is responsible for marking a point annotation
  with a view. Annotation views represent an annotation object, which is an
@@ -221,6 +246,12 @@ typedef NS_ENUM(NSUInteger, MGLAnnotationViewDragState) {
  */
 - (void)setDragState:(MGLAnnotationViewDragState)dragState animated:(BOOL)animated NS_REQUIRES_SUPER;
 
+/**
+ The current locking of the axis of the annotation view
+ By default the view is unlocked along both degree of freedom
+ */
+@property (nonatomic, assign) MGLAnnotationViewBillboardLocking lockAxis;
+
 @end
 
 NS_ASSUME_NONNULL_END

platform/ios/src/MGLAnnotationView.mm

@@ -11,7 +11,13 @@ @interface MGLAnnotationView () <UIGestureRecognizerDelegate>
 
 @property (nonatomic, readwrite, nullable) NSString *reuseIdentifier;
 @property (nonatomic, readwrite, nullable) id <MGLAnnotation> annotation;
+
 @property (nonatomic, readwrite) CATransform3D lastAppliedScaleTransform;
+
+@property (nonatomic, readwrite) CATransform3D lastAppliedTiltTransform;
+
+@property (nonatomic, readwrite) CATransform3D lastAppliedHeadingTransform;
+
 @property (nonatomic, weak) UIPanGestureRecognizer *panGestureRecognizer;
 @property (nonatomic, weak) UILongPressGestureRecognizer *longPressRecognizer;
 @property (nonatomic, weak) MGLMapView *mapView;
@@ -26,9 +32,12 @@ - (instancetype)initWithReuseIdentifier:(NSString *)reuseIdentifier
     if (self)
     {
         _lastAppliedScaleTransform = CATransform3DIdentity;
+        _lastAppliedTiltTransform = CATransform3DIdentity;
+        _lastAppliedHeadingTransform = CATransform3DIdentity;
         _reuseIdentifier = [reuseIdentifier copy];
         _scalesWithViewingDistance = YES;
         _enabled = YES;
+        _lockAxis = MGLAnnotationViewBillboardLockingAll;
     }
     return self;
 }
@@ -70,15 +79,47 @@ - (void)setCenter:(CGPoint)center
     center.y += _centerOffset.dy;
 
     super.center = center;
-    [self updateScaleTransformForViewingDistance];
+
+    [self updateTransform];
 }
 
 - (void)setScalesWithViewingDistance:(BOOL)scalesWithViewingDistance
 {
     if (_scalesWithViewingDistance != scalesWithViewingDistance)
     {
         _scalesWithViewingDistance = scalesWithViewingDistance;
-        [self updateScaleTransformForViewingDistance];
+        [self updateTransform];
+    }
+}
+
+- (void)updateTransform
+{
+    [self updateTiltTransform];
+    [self updateHeadingTransform];
+//    [self updateScaleTransformForViewingDistance];
+}
+
+- (void)updateHeadingTransform
+{
+    if( _lockAxis & MGLAnnotationViewBillboardLockingHeading ) {
+        const mbgl::TransformState mapTransform = self.mapView.mbglMap->getTransform();
+        CATransform3D undoOfLastHeadingTransform = CATransform3DInvert(_lastAppliedHeadingTransform);
+        CATransform3D newHeadingTransform = CATransform3DMakeRotation(mapTransform.getAngle(), 0, 0, 1);
+        CATransform3D effectiveTransform = CATransform3DConcat(undoOfLastHeadingTransform, newHeadingTransform);
+        self.layer.transform = CATransform3DConcat(self.layer.transform, effectiveTransform);
+        _lastAppliedHeadingTransform = newHeadingTransform;
+    }
+}
+
+- (void)updateTiltTransform
+{
+    if( _lockAxis & MGLAnnotationViewBillboardLockingTilt ) {
+        const mbgl::TransformState mapTransform = self.mapView.mbglMap->getTransform();
+        CATransform3D undoOfLastTiltTransform = CATransform3DInvert(_lastAppliedTiltTransform);
+        CATransform3D newTiltTransform = CATransform3DMakeRotation(mapTransform.getPitch(), 1, 0, 0);
+        CATransform3D effectiveTransform = CATransform3DConcat(undoOfLastTiltTransform, newTiltTransform);
+        self.layer.transform = CATransform3DConcat(self.layer.transform, effectiveTransform);
+        _lastAppliedTiltTransform = newTiltTransform;
     }
 }
 

platform/ios/src/MGLAnnotationView_Private.h

@@ -11,6 +11,8 @@ NS_ASSUME_NONNULL_BEGIN
 @property (nonatomic, readwrite, nullable) id <MGLAnnotation> annotation;
 @property (nonatomic, weak) MGLMapView *mapView;
 
+-(void)updateTransform;
+
 @end
 
 NS_ASSUME_NONNULL_END

platform/ios/src/MGLMapView.mm

@@ -2989,6 +2989,10 @@ - (void)updateAnnotationContainerViewWithAnnotationViews:(NS_ARRAY_OF(MGLAnnotat
     [newAnnotationContainerView addSubviews:annotationViews];
     [_glView insertSubview:newAnnotationContainerView atIndex:0];
     self.annotationContainerView = newAnnotationContainerView;
+
+    CATransform3D perspectiveTransform = CATransform3DIdentity;
+    perspectiveTransform.m34 = -1.0 / 500;
+    self.annotationContainerView.layer.sublayerTransform = perspectiveTransform;
 }
 
 /// Initialize and return a default annotation image that depicts a round pin
@@ -4638,6 +4642,8 @@ - (void)updateAnnotationViews
         {
             annotationView.center = [self convertCoordinate:annotationContext.annotation.coordinate toPointToView:self];
         }
+
+//        [annotationView updateTransform];
     }
 
     [CATransaction commit];