Code:

/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Core / CSharp / System / Windows / Media3D / Camera.cs / 1305600 / Camera.cs 

    //---------------------------------------------------------------------------- 
//
// 
//    Copyright (C) Microsoft Corporation.  All rights reserved.
//  
//
//--------------------------------------------------------------------------- 
 
using System;
using System.Diagnostics; 
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Media.Composition;
 
namespace System.Windows.Media.Media3D
{ 
    ///  
    ///     The Camera is the mechanism by which a 3D model is projected onto
    ///     a 2D visual.  The Camera itself is an abstract base class. 
    /// 
    public abstract partial class Camera : Animatable
    {
        //----------------------------------------------------- 
        //
        //  Constructors 
        // 
        //-----------------------------------------------------
 
        // Prevent 3rd parties from extending this abstract base class.
        internal Camera() {}

        //------------------------------------------------------ 
        //
        //  Public Methods 
        // 
        //-----------------------------------------------------
 
        //------------------------------------------------------
        //
        //  Public Properties
        // 
        //------------------------------------------------------
 
        //----------------------------------------------------- 
        //
        //  Public Events 
        //
        //------------------------------------------------------

        //----------------------------------------------------- 
        //
        //  Internal Methods 
        // 
        //-----------------------------------------------------
 
        #region Internal Methods

        // Creates a ray by projecting the given point on the viewport into the scene.
        // Used for bridging 2D -> 3D hit testing. 
        //
        // The latter two parameters in this method are used to deal with the 
        // case where the camera's near plane is far away from the viewport 
        // contents. In these cases, we can sometimes construct a new, closer,
        // near plane and start the ray on that plane. To do this, we need an 
        // axis-aligned bounding box of the viewport's contents (boundingRect).
        // We also need to return the distance between the original an new near
        // planes (distanceAdjustment), so we can correct the hit-test
        // distances before handing them back to the user. For more 
        // information, see WindowsOS Bug #1329733.
        // 
        internal abstract RayHitTestParameters RayFromViewportPoint(Point point, Size viewSize, Rect3D boundingRect, out double distanceAdjustment); 
        internal abstract Matrix3D GetViewMatrix();
        internal abstract Matrix3D GetProjectionMatrix(double aspectRatio); 

        internal static void PrependInverseTransform(Transform3D transform, ref Matrix3D viewMatrix)
        {
            if (transform != null && transform != Transform3D.Identity) 
            {
                PrependInverseTransform(transform.Value, ref viewMatrix); 
            } 
        }
 
        // Helper method to prepend the inverse of Camera.Transform to the
        // the given viewMatrix.  This is used by the various GetViewMatrix()
        // and RayFromViewportPoint implementations.
        // 
        // Transforming the camera is equivalent to applying the inverse
        // transform to the scene.  We invert the transform and prepend it to 
        // the result of viewMatrix: 
        //
        //                                  -1 
        //     viewMatrix = Camera.Transform   x viewMatrix
        //
        // If the matrix is non-invertable we set the viewMatrix to NaNs which
        // will result in nothing being rendered.  This is the correct behavior 
        // since the near and far planes will have collapsed onto each other.
        internal static void PrependInverseTransform(Matrix3D matrix, ref Matrix3D viewMatrix) 
        { 
            if (!matrix.InvertCore())
            { 
                // If the matrix is non-invertable we return a NaN matrix.
                viewMatrix = new Matrix3D(
                    double.NaN, double.NaN, double.NaN, double.NaN,
                    double.NaN, double.NaN, double.NaN, double.NaN, 
                    double.NaN, double.NaN, double.NaN, double.NaN,
                    double.NaN, double.NaN, double.NaN, double.NaN); 
            } 
            else
            { 
                viewMatrix.Prepend(matrix);
            }
        }
 

 
        #endregion Internal Methods 

        //----------------------------------------------------- 
        //
        //  Internal Properties
        //
        //------------------------------------------------------ 

        #region Internal Properties 
 
        #endregion Internal Properties
 
        //-----------------------------------------------------
        //
        //  Private Fields
        // 
        //------------------------------------------------------
 
        #region Private Fields 

        #endregion Private Fields 

    }
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.