1 files changed, 122 insertions, 0 deletions

diff --git a/OpenSim/Region/Framework/Scenes/Prioritizer.cs b/OpenSim/Region/Framework/Scenes/Prioritizer.cs
new file mode 100644
index 0000000..af25014
--- /dev/null
+++ b/OpenSim/Region/Framework/Scenes/Prioritizer.cs
@@ -0,0 +1,122 @@
+using System;
+using System.Collections.Generic;
+using log4net;
+using Nini.Config;
+using OpenSim.Framework;
+using OpenMetaverse;
+
+namespace OpenSim.Region.Framework.Scenes
+{
+    public enum UpdatePrioritizationSchemes
+    {
+        Time = 0,
+        Distance = 1,
+        SimpleAngularDistance = 2,
+        FrontBack = 3,
+    }
+
+    public class Prioritizer
+    {
+        private static readonly ILog m_log = LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);
+
+        private Scene m_scene;
+
+        public Prioritizer(Scene scene)
+        {
+            m_scene = scene;
+        }
+
+        public double GetUpdatePriority(IClientAPI client, ISceneEntity entity)
+        {
+            switch (m_scene.UpdatePrioritizationScheme)
+            {
+                case UpdatePrioritizationSchemes.Time:
+                    return GetPriorityByTime();
+                case UpdatePrioritizationSchemes.Distance:
+                    return GetPriorityByDistance(client, entity);
+                case UpdatePrioritizationSchemes.SimpleAngularDistance:
+                    return GetPriorityByDistance(client, entity);
+                case UpdatePrioritizationSchemes.FrontBack:
+                    return GetPriorityByFrontBack(client, entity);
+                default:
+                    throw new InvalidOperationException("UpdatePrioritizationScheme not defined.");
+            }
+        }
+
+        private double GetPriorityByTime()
+        {
+            return DateTime.UtcNow.ToOADate();
+        }
+
+        private double GetPriorityByDistance(IClientAPI client, ISceneEntity entity)
+        {
+            ScenePresence presence = m_scene.GetScenePresence(client.AgentId);
+            if (presence != null)
+            {
+                // If this is an update for our own avatar give it the highest priority
+                if (presence == entity)
+                    return 0.0;
+
+                // Use the camera position for local agents and avatar position for remote agents
+                Vector3 presencePos = (presence.IsChildAgent) ?
+                    presence.AbsolutePosition :
+                    presence.CameraPosition;
+
+                // Use group position for child prims
+                Vector3 entityPos;
+                if (entity is SceneObjectPart)
+                    entityPos = m_scene.GetGroupByPrim(entity.LocalId).AbsolutePosition;
+                else
+                    entityPos = entity.AbsolutePosition;
+
+                return Vector3.DistanceSquared(presencePos, entityPos);
+            }
+
+            return double.NaN;
+        }
+
+        private double GetPriorityByFrontBack(IClientAPI client, ISceneEntity entity)
+        {
+            ScenePresence presence = m_scene.GetScenePresence(client.AgentId);
+            if (presence != null)
+            {
+                // If this is an update for our own avatar give it the highest priority
+                if (presence == entity)
+                    return 0.0;
+
+                // Use group position for child prims
+                Vector3 entityPos = entity.AbsolutePosition;
+                if (entity is SceneObjectPart)
+                    entityPos = m_scene.GetGroupByPrim(entity.LocalId).AbsolutePosition;
+                else
+                    entityPos = entity.AbsolutePosition;
+
+                if (!presence.IsChildAgent)
+                {
+                    // Root agent. Use distance from camera and a priority decrease for objects behind us
+                    Vector3 camPosition = presence.CameraPosition;
+                    Vector3 camAtAxis = presence.CameraAtAxis;
+
+                    // Distance
+                    double priority = Vector3.DistanceSquared(camPosition, entityPos);
+
+                    // Plane equation
+                    float d = -Vector3.Dot(camPosition, camAtAxis);
+                    float p = Vector3.Dot(camAtAxis, entityPos) + d;
+                    if (p < 0.0f) priority *= 2.0;
+
+                    return priority;
+                }
+                else
+                {
+                    // Child agent. Use the normal distance method
+                    Vector3 presencePos = presence.AbsolutePosition;
+
+                    return Vector3.DistanceSquared(presencePos, entityPos);
+                }
+            }
+
+            return double.NaN;
+        }
+    }
+}