From 6ee9f75e293afb2b886ef3f6931f9997d879147e Mon Sep 17 00:00:00 2001
From: UnknownShadow200 <unknownshadow200@gmail.com>
Date: Wed, 27 Apr 2016 19:35:45 +1000
Subject: [PATCH] Initial work on new collision engine.

---
 ClassicalSharp/ClassicalSharp.csproj          |  1 +
 .../Components/CollisionsComponent.cs         | 12 +--
 .../Components/NewCollisionsComponent.cs      | 78 +++++++++++++++++++
 3 files changed, 83 insertions(+), 8 deletions(-)
 create mode 100644 ClassicalSharp/Entities/Components/NewCollisionsComponent.cs

diff --git a/ClassicalSharp/ClassicalSharp.csproj b/ClassicalSharp/ClassicalSharp.csproj
index b4e409999..615ce0d86 100644
--- a/ClassicalSharp/ClassicalSharp.csproj
+++ b/ClassicalSharp/ClassicalSharp.csproj
@@ -153,6 +153,7 @@
     <Compile Include="Entities\Components\InputComponent.cs" />
     <Compile Include="Entities\Components\InterpolatedComponent.cs" />
     <Compile Include="Entities\Components\CollisionsComponent.cs" />
+    <Compile Include="Entities\Components\NewCollisionsComponent.cs" />
     <Compile Include="Entities\Components\PhysicsComponent.cs" />
     <Compile Include="Entities\Components\ShadowComponent.cs" />
     <Compile Include="Entities\Components\SoundComponent.cs" />
diff --git a/ClassicalSharp/Entities/Components/CollisionsComponent.cs b/ClassicalSharp/Entities/Components/CollisionsComponent.cs
index 24d950e46..9cfaa589b 100644
--- a/ClassicalSharp/Entities/Components/CollisionsComponent.cs
+++ b/ClassicalSharp/Entities/Components/CollisionsComponent.cs
@@ -53,18 +53,14 @@ namespace ClassicalSharp.Entities {
 			Vector3 size = entity.CollisionSize;
 			BoundingBox entityBB, entityExtentBB;
 			int count = 0;
-			FindReachableBlocks( ref count, ref size, out entityBB, out entityExtentBB );
+			FindReachableBlocks( ref count, out entityBB, out entityExtentBB );
 			CollideWithReachableBlocks( count, ref size, ref entityBB, ref entityExtentBB );
 		}
 		
-		void FindReachableBlocks( ref int count, ref Vector3 size,
-		                         out BoundingBox entityBB, out BoundingBox entityExtentBB ) {
+		void FindReachableBlocks( ref int count, out BoundingBox entityBB, 
+		                         out BoundingBox entityExtentBB ) {
 			Vector3 vel = entity.Velocity;
-			Vector3 pos = entity.Position;
-			entityBB = new BoundingBox(
-				pos.X - size.X / 2, pos.Y, pos.Z - size.Z / 2,
-				pos.X + size.X / 2, pos.Y + size.Y, pos.Z + size.Z / 2
-			);
+			entityBB = entity.CollisionBounds;
 			
 			// Exact maximum extent the entity can reach, and the equivalent map coordinates.
 			entityExtentBB = new BoundingBox(
diff --git a/ClassicalSharp/Entities/Components/NewCollisionsComponent.cs b/ClassicalSharp/Entities/Components/NewCollisionsComponent.cs
new file mode 100644
index 000000000..872a8bdcd
--- /dev/null
+++ b/ClassicalSharp/Entities/Components/NewCollisionsComponent.cs
@@ -0,0 +1,78 @@
+// ClassicalSharp copyright 2014-2016 UnknownShadow200 | Licensed under MIT
+using System;
+using OpenTK;
+
+#if false
+namespace ClassicalSharp.Entities {
+	
+	/// <summary> Entity component that performs collision detection. </summary>
+	public sealed class NewCollisionsComponent {
+		
+		Game game;
+		Entity entity;
+		BlockInfo info;
+		static BoundingBox bb;
+		static RayTracer tracerP1Y1 = new RayTracer();
+		static RayTracer tracerP2Y1 = new RayTracer();
+		static RayTracer tracerP1Y2 = new RayTracer();
+		static RayTracer tracerP2Y2 = new RayTracer();
+		
+		public NewCollisionsComponent( Game game, Entity entity ) {
+			this.game = game;
+			this.entity = entity;
+			info = game.BlockInfo;
+		}
+		
+		internal unsafe void MoveAndWallSlide() {
+			if( entity.Velocity == Vector3.Zero ) return;
+			int* minY = stackalloc int[4096];
+			int* maxY = stackalloc int[4096];
+			int* minX = stackalloc int[4096];
+			int* maxX = stackalloc int[4096];
+			
+			for( int i = 0; i < 4096; i++ ) {
+				minX[i] = int.MaxValue; minY[i] = int.MaxValue;
+				maxX[i] = int.MinValue; maxY[i] = int.MinValue;
+			}
+			bb = entity.CollisionBounds;
+			int count = 0;
+			
+			// First raytrace out from the origin to find approximate blocks
+			CalcRayDirection();
+			while( true ) {
+				UpdateCoords( tracerP1Y1, minX, maxX, minY, maxY );
+				UpdateCoords( tracerP1Y2, minX, maxX, minY, maxY );
+				UpdateCoords( tracerP2Y1, minX, maxX, minY, maxY );
+				UpdateCoords( tracerP2Y2, minX, maxX, minY, maxY );
+			}
+			
+			// Now precisely which blocks we really intersect with
+			
+			// .. then perform collision
+		}
+		
+		void UpdateCoords( RayTracer tracer, int* minX, int* maxX, 
+		                  int* minY, int* maxY, ref int count ) {
+			tracer.Step();
+			minX[tracer.Z] = Math.Min( tracer.X, minX[tracer.Z] );
+			minY[tracer.Z] = Math.Min( tracer.Y, minY[tracer.Z] );
+			maxX[tracer.Z] = Math.Max( tracer.X, maxX[tracer.Z] );
+			maxY[tracer.Z] = Math.Max( tracer.Y, maxY[tracer.Z] );
+			count = Math.Max( count, tracer.Z );
+		}
+		
+		void CalcRayDirection() {
+			Vector3 dir = entity.Velocity;
+			Vector3 P = new Vector3( bb.Min.X, bb.Min.Y, bb.Max.Z );
+			tracerP1Y1.SetRayData( P, dir );
+			P.Y = bb.Max.Y;
+			tracerP1Y1.SetRayData( P, dir );
+			
+			P = new Vector3( bb.Max.X, bb.Min.Y, bb.Min.Z );
+			tracerP2Y1.SetRayData( P, dir );
+			P.Y = bb.Max.Y;
+			tracerP2Y2.SetRayData( P, dir );
+		}
+	}
+}
+#endif
\ No newline at end of file