///
///    This file is part of ILNumerics Community Edition.
///
///    ILNumerics Community Edition - high performance computing for applications.
///    Copyright (C) 2006 - 2012 Haymo Kutschbach, http://ilnumerics.net
///
///    ILNumerics Community Edition is free software: you can redistribute it and/or modify
///    it under the terms of the GNU General Public License version 3 as published by
///    the Free Software Foundation.
///
///    ILNumerics Community Edition is distributed in the hope that it will be useful,
///    but WITHOUT ANY WARRANTY; without even the implied warranty of
///    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
///    GNU General Public License for more details.
///
///    You should have received a copy of the GNU General Public License
///    along with ILNumerics Community Edition. See the file License.txt in the root
///    of your distribution package. If not, see <http://www.gnu.org/licenses/>.
///
///    In addition this software uses the following components and/or licenses: 
///
///    =================================================================================
///    The Open Toolkit Library License
///    
///    Copyright (c) 2006 - 2009 the Open Toolkit library.
///    
///    Permission is hereby granted, free of charge, to any person obtaining a copy
///    of this software and associated documentation files (the "Software"), to deal
///    in the Software without restriction, including without limitation the rights to 
///    use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
///    the Software, and to permit persons to whom the Software is furnished to do
///    so, subject to the following conditions:
///
///    The above copyright notice and this permission notice shall be included in all
///    copies or substantial portions of the Software.
///
///    =================================================================================
///    

using System;
using System.Collections.Generic;
using System.Text;
using ILNumerics.Drawing.Interfaces; 
using ILNumerics.Drawing.Lighting;
using ILNumerics.Drawing; 
using ILNumerics.Exceptions; 

namespace ILNumerics.Drawing.Shapes {
    /// <summary>
    /// Base class for all simple, bordered shapes to be used within ILNumerics.Drawing scene graphs
    /// </summary>
    /// <typeparam name="VertexType"></typeparam>
    public abstract class ILLitBorderedShape<VertexType>
        : ILBorderedShape<VertexType>, IILSupportsLight
        where VertexType : struct, IILVertexDefinition {

        #region attributes
        ILMaterial m_material;
        bool m_autoNormals;
        bool m_mustCalcNormals; 
        #endregion

        #region properties
        public ILMaterial Material {
            get {
                return m_material; 
            }
        }
        public bool AutoNormals {
            get { return m_autoNormals; }
            set {
                if (VerticesPerShape < 3 && value)
                    throw new InvalidOperationException(
                            "'auto normals' needs at least 3 vertices per primitive!");
                m_autoNormals = value;
                if (value) Configure();
            }
        }
        #endregion

        public ILLitBorderedShape(ILPanel panel, int numVertices)
        : base(panel, numVertices) {
            if (!VertexDefinition.StoresNormals)
                throw new ILInvalidOperationException("The generic vertex type does not support ligthing operations. Choose a vertext type which is able to store individual normal vectors!"); 
            m_autoNormals = true;
            m_material = new ILMaterial();
            m_mustCalcNormals = true; 
        }

        #region public
        public override void Configure() {
            if (m_visible) {
                if (m_mustCalcNormals && m_autoNormals) {
                    Computation.CalculateNormals(m_vertices);
                }
            }
            base.Configure();
        }
        public override void Invalidate() {
            base.Invalidate();
            m_mustCalcNormals = true; 
        }
        #endregion

        private class Computation : ILNumerics.ILMath {
            public static void CalculateNormals (VertexType[] vertices) {
                if (vertices.Length < 3) return;
                // crossproduct of vertex: (#1 - #0) x (#2 - #0)
                ILPoint3Df cross = ILPoint3Df.crossN(
                    vertices[1].Position - vertices[0].Position,
                    vertices[1].Position - vertices[2].Position);
                for (int i = 0; i < vertices.Length; i++) {
                    vertices[i].Normal = cross;  
                }

            }
        }
    }

}