OpenNest/OpenNest.Core/Geometry/BoundingBox.cs

using System.Collections.Generic;
using System.Linq;

namespace OpenNest.Geometry
{
    public static class BoundingBox
    {
        public static Box GetBoundingBox(this IList<Box> boxes)
        {
            if (boxes.Count == 0)
                return Box.Empty;

            double minX = boxes[0].X;
            double minY = boxes[0].Y;
            double maxX = boxes[0].Right;
            double maxY = boxes[0].Top;

            foreach (var box in boxes)
            {
                if (box.Left < minX)
                    minX = box.Left;
                if (box.Right > maxX)
                    maxX = box.Right;
                if (box.Bottom < minY)
                    minY = box.Bottom;
                if (box.Top > maxY)
                    maxY = box.Top;
            }

            return new Box(minX, minY, maxX - minX, maxY - minY);
        }

        public static Box GetBoundingBox(this IList<Vector> pts)
        {
            if (pts.Count == 0)
                return Box.Empty;

            var first = pts[0];
            var minX = first.X;
            var maxX = first.X;
            var minY = first.Y;
            var maxY = first.Y;

            for (int i = 1; i < pts.Count; ++i)
            {
                var vertex = pts[i];

                if (vertex.X < minX)
                    minX = vertex.X;
                else if (vertex.X > maxX)
                    maxX = vertex.X;

                if (vertex.Y < minY)
                    minY = vertex.Y;
                else if (vertex.Y > maxY)
                    maxY = vertex.Y;
            }

            return new Box(minX, minY, maxX - minX, maxY - minY);
        }

        public static Box GetBoundingBox(this IEnumerable<IBoundable> items)
        {
            var first = items.FirstOrDefault();

            if (first == null)
                return Box.Empty;

            double left = first.Left;
            double bottom = first.Bottom;
            double right = first.Right;
            double top = first.Top;

            foreach (var box in items)
            {
                if (box.Left < left)
                    left = box.Left;
                if (box.Right > right)
                    right = box.Right;
                if (box.Bottom < bottom)
                    bottom = box.Bottom;
                if (box.Top > top)
                    top = box.Top;
            }

            return new Box(left, bottom, right - left, top - bottom);
        }

        /// <summary>
        /// Whether <paramref name="inner"/> lies inside <paramref name="outer"/>, allowing
        /// <see cref="Math.Tolerance.Epsilon"/> on every side.
        /// </summary>
        internal static bool IsWithin(Box inner, Box outer)
        {
            var eps = Math.Tolerance.Epsilon;
            return inner.Left >= outer.Left - eps
                && inner.Right <= outer.Right + eps
                && inner.Bottom >= outer.Bottom - eps
                && inner.Top <= outer.Top + eps;
        }

        /// <summary>The smallest box covering both boxes.</summary>
        internal static Box Union(Box a, Box b)
        {
            var left = System.Math.Min(a.Left, b.Left);
            var bottom = System.Math.Min(a.Bottom, b.Bottom);
            var right = System.Math.Max(a.Right, b.Right);
            var top = System.Math.Max(a.Top, b.Top);
            return new Box(left, bottom, right - left, top - bottom);
        }
    }
}