From 5f0ab1f62dc4083575754e069e5be33e69e9f814 Mon Sep 17 00:00:00 2001
From: Paul Chote <paul@chote.net>
Date: Sat, 8 Jun 2013 14:13:47 +1200
Subject: [PATCH] Add functions for calculating voxel bounding boxes.

---
 OpenRA.Game/Graphics/Util.cs  | 29 +++++++++++++++++++++++++++++
 OpenRA.Game/Graphics/Voxel.cs | 27 +++++++++++++++++++++++++++
 2 files changed, 56 insertions(+)

diff --git a/OpenRA.Game/Graphics/Util.cs b/OpenRA.Game/Graphics/Util.cs
index 1d08371ddb..278c514f93 100644
--- a/OpenRA.Game/Graphics/Util.cs
+++ b/OpenRA.Game/Graphics/Util.cs
@@ -8,6 +8,7 @@
  */
 #endregion
 
+using System;
 using OpenRA.FileFormats.Graphics;
 
 namespace OpenRA.Graphics
@@ -229,5 +230,33 @@ namespace OpenRA.Graphics
 
 			return mtx;
 		}
+
+		public static float[] MatrixAABBMultiply(float[] mtx, float[] bounds)
+		{
+			// Corner offsets
+			var ix = new uint[] {0,0,0,0,3,3,3,3};
+			var iy = new uint[] {1,1,4,4,1,1,4,4};
+			var iz = new uint[] {2,5,2,5,2,5,2,5};
+
+			// Vectors to opposing corner
+			var ret = new float[] {float.MaxValue, float.MaxValue, float.MaxValue,
+				float.MinValue, float.MinValue, float.MinValue};
+
+			// Transform vectors and find new bounding box
+			for (var i = 0; i < 8; i++)
+			{
+				var vec = new float[] {bounds[ix[i]], bounds[iy[i]], bounds[iz[i]], 1};
+				var tvec = Util.MatrixVectorMultiply(mtx, vec);
+
+				ret[0] = Math.Min(ret[0], tvec[0]/tvec[3]);
+				ret[1] = Math.Min(ret[1], tvec[1]/tvec[3]);
+				ret[2] = Math.Min(ret[2], tvec[2]/tvec[3]);
+				ret[3] = Math.Max(ret[3], tvec[0]/tvec[3]);
+				ret[4] = Math.Max(ret[4], tvec[1]/tvec[3]);
+				ret[5] = Math.Max(ret[5], tvec[2]/tvec[3]);
+			}
+
+			return ret;
+		}
 	}
 }
diff --git a/OpenRA.Game/Graphics/Voxel.cs b/OpenRA.Game/Graphics/Voxel.cs
index dcabecfcd3..d69500cf97 100644
--- a/OpenRA.Game/Graphics/Voxel.cs
+++ b/OpenRA.Game/Graphics/Voxel.cs
@@ -164,5 +164,32 @@ namespace OpenRA.Graphics
 					});
 			}
 		}
+
+		public float[] Bounds(uint frame)
+		{
+			var ret = new float[] {float.MaxValue,float.MaxValue,float.MaxValue,
+				float.MinValue,float.MinValue,float.MinValue};
+
+			for (uint j = 0; j < limbs.Length; j++)
+			{
+				var b = new float[]
+				{
+					0, 0, 0,
+					(limbs[j].Bounds[3] - limbs[j].Bounds[0]),
+					(limbs[j].Bounds[4] - limbs[j].Bounds[1]),
+					(limbs[j].Bounds[5] - limbs[j].Bounds[2])
+				};
+
+				// Calculate limb bounding box
+				var bb = Util.MatrixAABBMultiply(TransformationMatrix(j, frame), b);
+				for (var i = 0; i < 3; i++)
+				{
+					ret[i] = Math.Min(ret[i], bb[i]);
+					ret[i+3] = Math.Max(ret[i+3], bb[i+3]);
+				}
+			}
+
+			return ret;
+		}
 	}
 }