#region CPL License
/*
Nuclex Framework
Copyright (C) 2002-2009 Nuclex Development Labs

This library is free software; you can redistribute it and/or
modify it under the terms of the IBM Common Public License as
published by the IBM Corporation; either version 1.0 of the
License, or (at your option) any later version.

This library 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
IBM Common Public License for more details.

You should have received a copy of the IBM Common Public
License along with this library
*/
#endregion

using System;
using System.Collections.Generic;

using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;

using Nuclex.Graphics.Batching;

namespace Nuclex.Graphics.SpecialEffects.Particles.HighLevel {
#if false
  /// <summary>Renders particles as CPU-calculates billboards</summary>
  /// <typeparam name="ParticleType">Data type of the particles</typeparam>
  /// <remarks>
  ///   <para>
  ///     This default implementation of a particle renderer assumes that your particle
  ///     structure and your particle vertex are one and the same. This is in no way
  ///     a requirement, but has the advantage that the renderer is not required to
  ///     touch each and every particle to produce a vertex for it.
  ///   </para>
  ///   <para>
  ///     Particles are rendered as point sprites, so your effect should be capable
  ///     of processing vertices as such.
  ///   </para>
  /// </remarks>
  public class BillBoardParticleRenderer<ParticleType> : IParticleRenderer<ParticleType>
    where ParticleType : struct {

    /// <summary>Initializes a new point particle renderer</summary>
    /// <param name="effect">Effect that will be used to render the particle</param>
    public BillBoardParticleRenderer(Effect effect) :
      this(new EffectDrawContext(effect)) { }

    /// <summary>Initializes a new point particle renderer</summary>
    /// <param name="drawContext">
    ///   Draw context controlling the rendering of the particles
    /// </param>
    public BillBoardParticleRenderer(DrawContext drawContext) {
      if(drawContext == null) {
        throw new ArgumentException("Invalid draw context", "drawContext");
      }

      this.drawContext = drawContext;
    }

    /// <summary>Renders a series of particles</summary>
    /// <param name="particles">Particles that will be rendered</param>
    /// <param name="primitiveBatch">
    ///   Primitive batch that will receive the vertices generated by the particles
    /// </param>
    public void Render(
      ArraySegment<ParticleType> particles,
      PrimitiveBatch<ParticleType> primitiveBatch
    ) {
      Vector3 cameraPosition = this.Camera.Translation;
      Vector3 cameraUp = this.Camera.Up;
      Vector3 cameraForward = this.Camera.Forward;
      Matrix billboard;
    
      ParticleType tl, tr, bl, br;
      int end = particles.Offset + particles.Count;
      for(int index = particles.Offset; index < end; ++index) {
        tl = particles.Array[index];
        tr = tl;
        bl = tl;
        br = tl;
        
        Vector3 position;
        this.accessor.GetPosition(ref tl, out position);

        Matrix.CreateBillboard(
          ref position, ref cameraPosition, ref cameraUp, cameraForward, out billboard
        );
        
        Vector3 corner;
        corner.X = position.X + billboard.M11 + billboard.M21;
        corner.Y = position.Y + billboard.M12 + billboard.M22;
        corner.Z = position.Z + billboard.M13 + billboard.M23;
        this.accessor.SetPosition(ref tl, ref corner);
        corner.X = position.X - billboard.M11 + billboard.M21;
        corner.Y = position.Y - billboard.M12 + billboard.M22;
        corner.Z = position.Z - billboard.M13 + billboard.M23;
        this.accessor.SetPosition(ref tr, ref corner);
        corner.X = position.X + billboard.M11 - billboard.M21;
        corner.Y = position.Y + billboard.M12 - billboard.M22;
        corner.Z = position.Z + billboard.M13 - billboard.M23;
        this.accessor.SetPosition(ref bl, ref corner);
        corner.X = position.X - billboard.M11 - billboard.M21;
        corner.Y = position.Y - billboard.M12 - billboard.M22;
        corner.Z = position.Z - billboard.M13 - billboard.M23;
        this.accessor.SetPosition(ref br, ref corner);
      }
      primitiveBatch.Draw(
        particles.Array, particles.Offset, particles.Count,
        PrimitiveType.PointList,
        this.drawContext
      );
    }
    
    public Matrix Camera;

    /// <summary>Draw context controlling the rendering of the particles</summary>
    private DrawContext drawContext;
    
    private IParticleAccessor<ParticleType> accessor;

  }
#endif
} // namespace Nuclex.Graphics.SpecialEffects.Particles.HighLevel