Proper render order for map elements

redhorizon-classic/source/nz/net/ultraq/redhorizon/classic/maps/Map.groovy

@@ -121,16 +121,27 @@ class Map extends Node<Map> {
 		rules = rulesIni as RulesFile
 
 		addChild(new MapBackground())
-		addChild(new MapPack())
-		addChild(new OverlayPack())
-		addChild(new Terrain())
-		addChild(new Structures())
-		addChild(new Units())
-		addChild(new Infantry())
+		addChild(new MapPack().tap {
+			setPosition(0, 0, 0.1f)
+		})
+		addChild(new OverlayPack().tap {
+			setPosition(0, 0, 0.2f)
+		})
+		addChild(new Terrain().tap {
+			setPosition(0, 0, 0.2f)
+		})
+		addChild(new Structures().tap {
+			setPosition(0, 0, 0.2f)
+		})
+		addChild(new Units().tap {
+			setPosition(0, 0, 0.2f)
+		})
+		addChild(new Infantry().tap {
+			setPosition(0, 0, 0.2f)
+		})
+
 		addChild(new MapLines().tap {
-			transform { ->
-				translate(0f, 0f, 0.1f)
-			}
+			setPosition(0, 0, 0.4f)
 		})
 	}
 

redhorizon-engine/source/nz/net/ultraq/redhorizon/engine/graphics/pipeline/RenderPipeline.groovy

@@ -183,12 +183,10 @@ class RenderPipeline implements AutoCloseable {
 		private final FrustumIntersection frustumIntersection = new FrustumIntersection()
 		private final List<Node> queryResults = []
 		private final List<RenderCommand> drawCommands = []
-		private final Comparator<Node> renderOrderComparator = new Comparator<Node>() {
-			@Override
-			int compare(Node node1, Node node2) {
-				return node1.globalPosition.z() <=> node2.globalPosition.z()
-			}
-		}
+
+		// Sorting seems to be more performant with separate sort functions
+		private final Comparator<Node> orderByDistance = Comparator.comparing { Node node -> node.globalPosition.z() }
+		private final Comparator<Node> orderByHighest = Comparator.comparing { Node node -> -node.globalPosition.y() }
 
 		Scene scene
 
@@ -214,11 +212,11 @@ class RenderPipeline implements AutoCloseable {
 				average('Gathering', 1f, logger) { ->
 					queryResults.clear()
 					drawCommands.clear()
-
 					drawCommands << scene.camera.renderCommand()
 					frustumIntersection.set(enlargedViewProjection.scaling(0.9f, 0.9f, 1f).mul(scene.camera.viewProjection), false)
 					scene.query(frustumIntersection, queryResults)
-						.sort(true, renderOrderComparator) // Furthest-away objects first
+						.sort(true, orderByHighest)
+						.sort(true, orderByDistance)
 						.each { node ->
 							if (node instanceof GraphicsElement) {
 								drawCommands << node.renderCommand()