render distant nodes behind closer nodes (#220)

* render distant nodes behind closer nodes * Use common code to calculate rendering order Code style changes to match rest of code base * Method comments get the triple slash treatment * Update changelog
AndrewHartAR · Sep 8, 2019 · 5804ee5 · 5804ee5
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diff --git a/Sources/ARKit-CoreLocation/Extensions/SCNNode+Extensions.swift b/Sources/ARKit-CoreLocation/Extensions/SCNNode+Extensions.swift
@@ -12,6 +12,7 @@ extension SCNNode {
     /// Overlapping nodes require unique renderingOrder values to avoid flicker
     /// This method will select random values if you don't care which node is in front of the other,
     /// or you can specify a particular z-order value
+    /// Note: rendering order will be changed later based on distance from camera
     func removeFlicker (withRenderingOrder renderingOrder: Int = Int.random(in: 1..<Int.max)) {
         self.renderingOrder = renderingOrder
         if let geom = geometry {

diff --git a/Sources/ARKit-CoreLocation/Nodes/LocationAnnotationNode.swift b/Sources/ARKit-CoreLocation/Nodes/LocationAnnotationNode.swift
@@ -59,6 +59,8 @@ open class LocationAnnotationNode: LocationNode {
 
         let distance = self.location(locationManager.bestLocationEstimate).distance(from: location)
 
+        childNodes.first?.renderingOrder = renderingOrder(fromDistance: distance)
+
         let adjustedDistance = self.adjustedDistance(setup: setup, position: position,
                                                      locationNodeLocation: nodeLocation, locationManager: locationManager)
 

diff --git a/Sources/ARKit-CoreLocation/Nodes/LocationNode.swift b/Sources/ARKit-CoreLocation/Nodes/LocationNode.swift
@@ -156,11 +156,23 @@ open class LocationNode: SCNNode {
         SCNTransaction.begin()
         SCNTransaction.animationDuration = setup ? 0.0 : 0.1
 
+        let distance = self.location(locationManager.bestLocationEstimate).distance(from:
+            locationManager.currentLocation ?? nodeLocation)
+
+        childNodes.first?.renderingOrder = renderingOrder(fromDistance: distance)
+
         _ = self.adjustedDistance(setup: setup, position: position,
                                   locationNodeLocation: nodeLocation, locationManager: locationManager)
 
         SCNTransaction.commit()
 
         onCompletion()
     }
+
+    /// Converts distance from meters to SCNKit rendering order
+    /// Constant multiplier eliminates flicker caused by slight distance variations
+    /// Nodes with greater rendering orders are rendered last
+    func renderingOrder(fromDistance distance: CLLocationDistance) -> Int {
+        return Int.max - 1000 - (Int(distance * 1000))
+    }
 }
diff --git a/changelog.md b/changelog.md
@@ -1,5 +1,6 @@
 # Changelog
 - 1.2.2
+   - [PR #220 - Render distant nodes behind closer nodes ](https://github.com/ProjectDent/ARKit-CoreLocation/pull/220)
 - 1.2.1
     - [PR #207 - Addresses Issue #136 - ARCL lacks CI ](https://github.com/ProjectDent/ARKit-CoreLocation/pull/207)
     - [PR #209 - Updates polyline position/scale when GPS location is updated](https://github.com/ProjectDent/ARKit-CoreLocation/pull/209)