// --------------------------------------------------------------------------------------------------------------------

// <copyright file="LinesVisual3D.cs" company="Helix 3D Toolkit">

//   http://helixtoolkit.codeplex.com, license: MIT

// </copyright>

// --------------------------------------------------------------------------------------------------------------------



namespace HelixToolkit.Wpf

{

    using System.Windows;



    /// <summary>

    /// A visual element that contains a set of line segments. The thickness of the lines is defined in screen space.

    /// </summary>

    public class LinesVisual3D : ScreenSpaceVisual3D

    {

        /// <summary>

        /// Identifies the <see cref="Thickness"/> dependency property.

        /// </summary>

        public static readonly DependencyProperty ThicknessProperty = DependencyProperty.Register(

            "Thickness", typeof(double), typeof(LinesVisual3D), new UIPropertyMetadata(1.0, GeometryChanged));



        /// <summary>

        /// The builder.

        /// </summary>

        private readonly LineGeometryBuilder builder;



        /// <summary>

        /// Initializes a new instance of the <see cref = "LinesVisual3D" /> class.

        /// </summary>

        public LinesVisual3D()

        {

            this.builder = new LineGeometryBuilder(this);

        }



        /// <summary>

        /// Gets or sets the thickness of the lines.

        /// </summary>

        /// <value>

        /// The thickness.

        /// </value>

        public double Thickness

        {

            get

            {

                return (double)this.GetValue(ThicknessProperty);

            }



            set

            {

                this.SetValue(ThicknessProperty, value);

            }

        }



        /// <summary>

        /// Updates the geometry.

        /// </summary>

        protected override void UpdateGeometry()

        {

            if (this.Points == null)

            {

                this.Mesh.Positions = null;

                return;

            }



            int n = this.Points.Count;

            if (n > 0)

            {

                if (this.Mesh.TriangleIndices.Count != n * 3)

                {

                    this.Mesh.TriangleIndices = this.builder.CreateIndices(n);

                }



                this.Mesh.Positions = this.builder.CreatePositions(this.Points, this.Thickness, this.DepthOffset);

            }

            else

            {

                this.Mesh.Positions = null;

            }

        }



        /// <summary>

        /// Updates the transforms.

        /// </summary>

        /// <returns>

        /// True if the transform is updated.

        /// </returns>

        protected override bool UpdateTransforms()

        {

            return this.builder.UpdateTransforms();

        }

    }

}