(61d00a474) v0.9.7.1

2020-03-04 13:04:10 +01:00
parent 3c50efa5c9
commit 3c09ebe02f
5086 changed files with 786063 additions and 295871 deletions
@@ -0,0 +1,95 @@
+/* Original source Farseer Physics Engine:
+ * Copyright (c) 2014 Ian Qvist, http://farseerphysics.codeplex.com
+ * Microsoft Permissive License (Ms-PL) v1.1
+ */
+
+using System;
+using System.Collections.Generic;
+using Microsoft.Xna.Framework;
+
+namespace FarseerPhysics.Fluids
+{
+    /// <summary>
+    /// Grid used by particle system to keep track of neightbor particles.
+    /// </summary>
+    public class HashGrid
+    {
+        private Dictionary<ulong, List<FluidParticle>> _hash = new Dictionary<ulong, List<FluidParticle>>();
+        private Stack<List<FluidParticle>> _bucketPool = new Stack<List<FluidParticle>>();
+
+        public HashGrid()
+        {
+            GridSize = 1.0f;
+        }
+
+        public float GridSize { get; set; }
+
+        private static ulong HashKey(int x, int y)
+        {
+            return ((ulong)x * 2185031351ul) ^ ((ulong)y * 4232417593ul);
+        }
+
+        private ulong HashKey(Vector2 position)
+        {
+            return HashKey(
+                (int)Math.Floor(position.X / GridSize),
+                (int)Math.Floor(position.Y / GridSize)
+            );
+        }
+
+        public void Clear()
+        {
+            foreach (KeyValuePair<ulong, List<FluidParticle>> pair in _hash)
+            {
+                pair.Value.Clear();
+                _bucketPool.Push(pair.Value);
+            }
+            _hash.Clear();
+        }
+
+        public void Add(FluidParticle particle)
+        {
+            ulong key = HashKey(particle.Position);
+            List<FluidParticle> bucket;
+            if (!_hash.TryGetValue(key, out bucket))
+            {
+                if (_bucketPool.Count > 0)
+                {
+                    bucket = _bucketPool.Pop();
+                }
+                else
+                {
+                    bucket = new List<FluidParticle>();
+                }
+                _hash.Add(key, bucket);
+            }
+            bucket.Add(particle);
+        }
+
+        public void Find(ref Vector2 position, List<FluidParticle> neighbours)
+        {
+            int ix = (int)Math.Floor(position.X / GridSize);
+            int iy = (int)Math.Floor(position.Y / GridSize);
+
+            // Check all 9 neighbouring cells
+            for (int x = ix - 1; x <= ix + 1; ++x)
+            {
+                for (int y = iy - 1; y <= iy + 1; ++y)
+                {
+                    ulong key = HashKey(x, y);
+                    List<FluidParticle> bucket;
+                    if (_hash.TryGetValue(key, out bucket))
+                    {
+                        for (int i = 0; i < bucket.Count; ++i)
+                        {
+                            if (bucket[i] != null)
+                            {
+                                neighbours.Add(bucket[i]);
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+}