RTS Volume selection

Selection.cs

using UnityEngine;
using System.Collections;
using System.Collections.Generic;
class Selection {
  List<Unit> static PickUnitsInRect(float left, float top, float right, float bottom, Camera camera = null) {
		List<Unit> pickedUnits = new List<Unit>();
		if(camera == null) camera = Camera.main;
		
		Ray bottomLeft = camera.ScreenPointToRay(new Vector3(left, bottom));
		Ray topLeft = camera.ScreenPointToRay(new Vector3(left, top));
		Ray topRight = camera.ScreenPointToRay(new Vector3(right, top));
		Ray bottomRight = camera.ScreenPointToRay(new Vector3(right, bottom));
		
		Plane[] planes = new Plane[5];
		planes[0].Set3Points(topLeft.GetPoint(3), bottomLeft.GetPoint(3), bottomRight.GetPoint(3)); // front
		planes[1].Set3Points(topLeft.origin, topRight.origin, topRight.GetPoint(100)); // top
		planes[2].Set3Points(topLeft.origin, topLeft.GetPoint(100), bottomLeft.GetPoint(100)); //left
		planes[3].Set3Points(bottomLeft.origin,  bottomLeft.GetPoint(100), bottomRight.GetPoint(100));//bottom
		planes[4].Set3Points(topRight.origin, bottomRight.GetPoint(100), topRight.GetPoint(100)); //right
		
		foreach(Unit unit in Unit.units) {
			if(GeometryUtility.TestPlanesAABB(planes,unit.bounds)) {
				pickedUnits.Add(unit);	
			}
		}
		return pickedUnits;
	}
}