First commit.

Source/OpenNest.Engine/RectanglePacking/PackBottomLeft.cs

@@ -0,0 +1,115 @@
+using System.Collections.Generic;
+using System.Linq;
+
+namespace OpenNest.RectanglePacking
+{
+    internal class PackBottomLeft : PackEngine
+    {
+        private List<Vector> points;
+
+        public PackBottomLeft(Bin bin)
+            : base(bin)
+        {
+            points = new List<Vector>();
+        }
+
+        public override void Pack(List<Item> items)
+        {
+            items = items.OrderBy(i => -i.Area()).ToList();
+
+            points.Add(Bin.Location);
+
+            var skip = new List<int>();
+
+            for (int i = 0; i < items.Count; i++)
+            {
+                var item = items[i];
+
+                if (skip.Contains(item.Id))
+                    continue;
+
+                var pt = FindPointVertical(item);
+
+                if (pt == null)
+                {
+                    skip.Add(item.Id);
+                    continue;
+                }
+
+                item.Location = pt.Value;
+
+                points.Remove(pt.Value);
+                points.Add(new Vector(item.Left, item.Top));
+                points.Add(new Vector(item.Right, item.Bottom));
+
+                Bin.Items.Add(item);
+            }
+
+            points.Clear();
+        }
+
+        private Vector? FindPointVertical(Item item)
+        {
+            var pt = new Vector(double.MaxValue, double.MaxValue);
+
+            for (int i = 0; i < points.Count; i++)
+            {
+                var point = points[i];
+
+                item.Location = point;
+
+                if (!IsValid(item))
+                    continue;
+
+                if (point.X < pt.X)
+                    pt = point;
+                else if (point.X.IsEqualTo(pt.X) && point.Y < pt.Y)
+                    pt = point;
+            }
+
+            if (pt.X != double.MaxValue && pt.Y != double.MaxValue)
+                return pt;
+            
+            return null;
+        }
+
+        private Vector? FindPointHorizontal(Item item)
+        {
+            var pt = new Vector(double.MaxValue, double.MaxValue);
+
+            for (int i = 0; i < points.Count; i++)
+            {
+                var point = points[i];
+
+                item.Location = point;
+
+                if (!IsValid(item))
+                    continue;
+
+                if (point.Y < pt.Y)
+                    pt = point;
+                else if (point.Y.IsEqualTo(pt.Y) && point.X < pt.X)
+                    pt = point;
+            }
+
+            if (pt.X != double.MaxValue && pt.Y != double.MaxValue)
+                return pt;
+
+            return null;
+        }
+
+        private bool IsValid(Item item)
+        {
+            if (!Bin.Contains(item))
+                return false;
+
+            foreach (var it in Bin.Items)
+            {
+                if (item.Intersects(it))
+                    return false;
+            }
+
+            return true;
+        }
+    }
+}