#region License
/* FNA - XNA4 Reimplementation for Desktop Platforms
 * Copyright 2009-2016 Ethan Lee and the MonoGame Team
 *
 * Released under the Microsoft Public License.
 * See LICENSE for details.
 */
#endregion

namespace Microsoft.Xna.Framework.Graphics
{
	public struct VertexBufferBinding
	{
		#region Public Properties

		/// <summary>
		/// Gets the instance frequency. A value of 0 means no instancing.
		/// </summary>
		public int InstanceFrequency
		{
			get
			{
				return instanceFrequency;
			}
		}

		/// <summary>
		/// Gets the vertex buffer.
		/// </summary>
		public VertexBuffer VertexBuffer
		{
			get
			{
				return vertexBuffer;
			}
		}

		/// <summary>
		/// Gets the offset in bytes from the beginning of the vertex buffer to the first vertex to use.
		/// </summary>
		public int VertexOffset
		{
			get
			{
				return vertexOffset;
			}
		}

		#endregion

		#region Internal Static Properties

		/// <summary>
		/// A null vertex buffer binding for unused vertex buffer slots.
		/// </summary>
		internal static VertexBufferBinding None
		{
			get
			{
				return none;
			}
		}

		#endregion

		#region Private Variables

		private VertexBuffer vertexBuffer;
		private int vertexOffset;
		private int instanceFrequency;

		#endregion

		#region Private Static Variables

		private static VertexBufferBinding none = new VertexBufferBinding(null);

		#endregion

		#region Public Constructors

		/// <summary>
		/// Creates an instance of VertexBufferBinding.
		/// </summary>
		/// <param name="vertexBuffer">The vertex buffer to bind.</param>
		public VertexBufferBinding(VertexBuffer vertexBuffer)
		{
			this.vertexBuffer = vertexBuffer;
			vertexOffset = 0;
			instanceFrequency = 0;
		}

		/// <summary>
		/// Creates an instance of VertexBufferBinding.
		/// </summary>
		/// <param name="vertexBuffer">The vertex buffer to bind.</param>
		/// <param name="vertexOffset">The offset in bytes to the first vertex to use.</param>
		public VertexBufferBinding(VertexBuffer vertexBuffer, int vertexOffset)
		{
			this.vertexBuffer = vertexBuffer;
			this.vertexOffset = vertexOffset;
			instanceFrequency = 0;
		}

		/// <summary>
		/// Creates an instance of VertexBufferBinding.
		/// </summary>
		/// <param name="vertexBuffer">The vertex buffer to bind.</param>
		/// <param name="vertexOffset">The offset in bytes to the first vertex to use.</param>
		/// <param name="instanceFrequency">Number of instances to draw for each draw call. Use 0 if not using instanced drawing.</param>
		public VertexBufferBinding(VertexBuffer vertexBuffer, int vertexOffset, int instanceFrequency)
		{
			this.vertexBuffer = vertexBuffer;
			this.vertexOffset = vertexOffset;
			this.instanceFrequency = instanceFrequency;
		}

		#endregion

		#region Implicit Operators

		public static implicit operator VertexBufferBinding(VertexBuffer buffer)
		{
			return new VertexBufferBinding(buffer);
		}

		#endregion
	}
}