core: add nearClippedProjectionMatrix to MLNCustomStyleLayer (#4364)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Bart Louwers <bart@emeel.net>

include/mbgl/style/layers/custom_layer_render_parameters.hpp

@@ -22,8 +22,14 @@ struct CustomLayerRenderParameters {
     double bearing;
     double pitch;
     double fieldOfView;
+
+    /// Standard projection matrix (nearZ = 1 tile unit).
+    /// Use this for 2D/flat custom geometry.
     std::array<double, 16> projectionMatrix;
 
+    /// A 4×4 matrix representing the map view’s current near clip projection state.
+    std::array<double, 16> nearClippedProjectionMatrix;
+
     CustomLayerRenderParameters(const PaintParameters&);
 };
 

platform/darwin/src/MLNCustomStyleLayer.h

@@ -30,8 +30,10 @@ typedef struct MLNStyleLayerDrawingContext {
   CGFloat pitch;
   /// The vertical field of view, in degrees, for the map’s perspective.
   CGFloat fieldOfView;
-  /// A 4×4 matrix representing the map view’s current projection state.
+  /// Standard projection matrix (nearZ = 1 tile unit). Use for 2D/flat geometry.
   MLNMatrix4 projectionMatrix;
+  /// A 4×4 matrix representing the map view’s current near clip projection state.
+  MLNMatrix4 nearClippedProjectionMatrix;
 } MLNStyleLayerDrawingContext;
 
 /// A style layer that is rendered by Metal code that you provide.

platform/darwin/src/MLNCustomStyleLayer.mm

@@ -117,7 +117,8 @@ public:
         .direction = mbgl::util::wrap(parameters.bearing, 0., 360.),
         .pitch = static_cast<CGFloat>(parameters.pitch),
         .fieldOfView = static_cast<CGFloat>(parameters.fieldOfView),
-        .projectionMatrix = MLNMatrix4Make(parameters.projectionMatrix)};
+        .projectionMatrix = MLNMatrix4Make(parameters.projectionMatrix),
+        .nearClippedProjectionMatrix = MLNMatrix4Make(parameters.nearClippedProjectionMatrix)};
 
     if (layer.mapView) {
       [layer drawInMapView:layer.mapView withContext:drawingContext];

src/mbgl/style/layers/custom_layer_render_parameters.cpp

@@ -18,6 +18,7 @@ CustomLayerRenderParameters::CustomLayerRenderParameters(const mbgl::PaintParame
     mat4 projMatrix;
     state.getProjMatrix(projMatrix);
     projectionMatrix = projMatrix;
+    nearClippedProjectionMatrix = paintParameters.transformParams.nearClippedProjMatrix;
 }
 
 } // namespace style