/// <summary>
/// Converts the given point or ray hit test result into a PointHitTestResult.
/// In the case of a RayHitTestResult this is done by walking up the
/// transforming the 3D intersection into the coordinate space of the
/// Viewport3DVisual which contains the Visual3D subtree.
/// </summary>
internal static PointHitTestResult AsNearestPointHitTestResult(HitTestResult result)
{
if (result == null)
{
return(null);
}
PointHitTestResult resultAsPointHitTestResult = result as PointHitTestResult;
if (resultAsPointHitTestResult != null)
{
return(resultAsPointHitTestResult);
}
RayHitTestResult resultAsRayHitTestResult = result as RayHitTestResult;
if (resultAsRayHitTestResult != null)
{
Visual3D current = (Visual3D)resultAsRayHitTestResult.VisualHit;
Matrix3D worldTransform = Matrix3D.Identity;
while (true)
{
if (current.Transform != null)
{
worldTransform.Append(current.Transform.Value);
}
Visual3D parent3D = current.InternalVisualParent as Visual3D;
if (parent3D == null)
{
break;
}
current = parent3D;
}
Viewport3DVisual viewport = current.InternalVisualParent as Viewport3DVisual;
if (viewport != null)
{
Point4D worldPoint = ((Point4D)resultAsRayHitTestResult.PointHit) * worldTransform;
Point viewportPoint = viewport.WorldToViewport(worldPoint);
return(new PointHitTestResult(viewport, viewportPoint));
}
Debug.Fail("How did a ray hit a Visual3D not parented to a Viewport3DVisual?");
return(null);
}
Debug.Fail(String.Format("Unhandled HitTestResult type '{0}'", result.GetType().Name));
return(null);
}
