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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
//
//
using System.Windows.Media.Animation;
namespace System.Windows.Media.Media3D
{
/// <summary>
/// The Camera is the mechanism by which a 3D model is projected onto
/// a 2D visual. The Camera itself is an abstract base class.
/// </summary>
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.
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
}
}
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