From ffc49d163e91527619219f7219c33fdfc6a82a98 Mon Sep 17 00:00:00 2001
From: UnknownShadow200 <unknownshadow200@gmail.com>
Date: Sat, 27 Jun 2015 12:11:47 +1000
Subject: [PATCH] Better selection box sorting.

---
 Physics/Picking.cs                 |  3 +--
 Selections/SelectionBoxComparer.cs | 23 ++++++++++++-----------
 Selections/SelectionManager.cs     |  4 ++--
 3 files changed, 15 insertions(+), 15 deletions(-)

diff --git a/Physics/Picking.cs b/Physics/Picking.cs
index d1b814529..a814e53f8 100644
--- a/Physics/Picking.cs
+++ b/Physics/Picking.cs
@@ -72,9 +72,8 @@ namespace ClassicalSharp {
 			// which voxel boundary is nearest) and walk that way.
 			while( iterations < 10000 ) {
 				byte block = map.IsValidPos( x, y, z ) ? map.GetBlock( x, y, z ) : (byte)0;
-				float height = block == 0 ? 1 : info.BlockHeight( block );
 				Vector3 min = new Vector3( x, y, z );
-				Vector3 max = new Vector3( x + 1, y + height, z + 1 );
+				Vector3 max = min + new Vector3( 1, block == 0 ? 1 : info.BlockHeight( block ), 1 );
 				
 				float dx = Math.Min( Math.Abs( origin.X - min.X ), Math.Abs( origin.X - max.X ) );
 				float dy = Math.Min( Math.Abs( origin.Y - min.Y ), Math.Abs( origin.Y - max.Y ) );
diff --git a/Selections/SelectionBoxComparer.cs b/Selections/SelectionBoxComparer.cs
index a41c64d60..fadbb4514 100644
--- a/Selections/SelectionBoxComparer.cs
+++ b/Selections/SelectionBoxComparer.cs
@@ -13,27 +13,28 @@ namespace ClassicalSharp.Selections {
 			float maxDistA = float.NegativeInfinity, maxDistB = float.NegativeInfinity;
 			Intersect( a, pos, ref minDistA, ref maxDistA );
 			Intersect( b, pos, ref minDistB, ref maxDistB );
-			return maxDistA == maxDistB ? minDistA.CompareTo( minDistB ) : maxDistA.CompareTo( maxDistB );
+			// Reversed comparison order because we need to render back to front for alpha blending.
+			return minDistA == minDistB ? maxDistB.CompareTo( maxDistA ) : minDistB.CompareTo( minDistA );
 		}
 		
 		void Intersect( SelectionBox box, Vector3 origin, ref float closest, ref float furthest ) {
 			Vector3I min = box.Min;
 			Vector3I max = box.Max;
 			// Bottom corners
-			UpdateDist( pos.X, pos.Y, pos.Z, min.X, min.Y, min.Z, ref closest, ref furthest );
-			UpdateDist( pos.X, pos.Y, pos.Z, max.X, min.Y, min.Z, ref closest, ref furthest );
-			UpdateDist( pos.X, pos.Y, pos.Z, max.X, min.Y, max.Z, ref closest, ref furthest );
-			UpdateDist( pos.X, pos.Y, pos.Z, min.X, min.Y, max.Z, ref closest, ref furthest );
+			UpdateDist( pos, min.X, min.Y, min.Z, ref closest, ref furthest );
+			UpdateDist( pos, max.X, min.Y, min.Z, ref closest, ref furthest );
+			UpdateDist( pos, max.X, min.Y, max.Z, ref closest, ref furthest );
+			UpdateDist( pos, min.X, min.Y, max.Z, ref closest, ref furthest );
 			// top corners
-			UpdateDist( pos.X, pos.Y, pos.Z, min.X, max.Y, min.Z, ref closest, ref furthest );
-			UpdateDist( pos.X, pos.Y, pos.Z, max.X, max.Y, min.Z, ref closest, ref furthest );
-			UpdateDist( pos.X, pos.Y, pos.Z, max.X, max.Y, max.Z, ref closest, ref furthest );
-			UpdateDist( pos.X, pos.Y, pos.Z, min.X, max.Y, max.Z, ref closest, ref furthest );
+			UpdateDist( pos, min.X, max.Y, min.Z, ref closest, ref furthest );
+			UpdateDist( pos, max.X, max.Y, min.Z, ref closest, ref furthest );
+			UpdateDist( pos, max.X, max.Y, max.Z, ref closest, ref furthest );
+			UpdateDist( pos, min.X, max.Y, max.Z, ref closest, ref furthest );
 		}
 		
-		static void UpdateDist( float x1, float y1, float z1, float x2, float y2, float z2,
+		static void UpdateDist( Vector3 p, float x2, float y2, float z2,
 		                       ref float closest, ref float furthest ) {
-			float dist = Utils.DistanceSquared( x1, y1, z1, x2, y2, z2 );
+			float dist = Utils.DistanceSquared( p.X, p.Y, p.Z, x2, y2, z2 );
 			if( dist < closest ) closest = dist;
 			if( dist > furthest ) furthest = dist;
 		}
diff --git a/Selections/SelectionManager.cs b/Selections/SelectionManager.cs
index 4e7fa9f47..86c10632f 100644
--- a/Selections/SelectionManager.cs
+++ b/Selections/SelectionManager.cs
@@ -39,8 +39,8 @@ namespace ClassicalSharp.Selections {
 			Player player = Window.LocalPlayer;
 			pos = player.Position;
 			if( selections.Count == 0 ) return;
-			// Basically sorts selection boxes back to front for better transparency.
-			// TODO: Proper selection box sorting.
+			// TODO: Proper selection box sorting. But this is very difficult because
+			// we can have boxes within boxes, intersecting boxes, etc..
 			comparer.pos = pos;
 			selections.Sort( comparer );