private static Matrix3D GetProjectionMatrix(PerspectiveCamera camera, double aspectRatio)
{
Debug.Assert(camera != null,
"Caller needs to ensure camera is non-null.");
// This math is identical to what you find documented for
// D3DXMatrixPerspectiveFovRH with the exception that in
// WPF the camera's horizontal rather the vertical
// field-of-view is specified.
double hFoV = MUtils.DegreesToRadians(camera.FieldOfView);
double zn = camera.NearPlaneDistance;
double zf = camera.FarPlaneDistance;
double xScale = 1 / Math.Tan(hFoV / 2);
double yScale = aspectRatio * xScale;
double m33 = (zf == double.PositiveInfinity) ? -1 : (zf / (zn - zf));
double m43 = zn * m33;
return(new Matrix3D(
xScale, 0, 0, 0,
0, yScale, 0, 0,
0, 0, m33, -1,
0, 0, m43, 0));
}
/// <summary>
/// Computes the transform from the inner space of the given
/// Visual3D to the camera coordinate space
///
/// The result will contain the transform of the given visual.
///
/// This method can fail if Camera.Transform is non-invertable
/// in which case the camera clip planes will be coincident and
/// nothing will render. In this case success will be false.
/// </summary>
/// <param name="visual"></param>
/// <param name="success"></param>
/// <returns></returns>
public static Matrix3D TryTransformToCameraSpace(DependencyObject visual, out Viewport3DVisual viewport, out bool success)
{
Matrix3D toViewSpace = GetWorldTransformationMatrix(visual, out viewport);
toViewSpace.Append(MUtils.TryWorldToCameraTransform(viewport, out success));
if (!success)
{
return(ZeroMatrix);
}
return(toViewSpace);
}
/// <summary>
/// Computes the transform from the inner space of the given
/// Visual3D to the 2D space of the Viewport3DVisual which
/// contains it.
///
/// The result will contain the transform of the given visual.
///
/// This method can fail if Camera.Transform is non-invertable
/// in which case the camera clip planes will be coincident and
/// nothing will render. In this case success will be false.
/// </summary>
/// <param name="visual"></param>
/// <param name="success"></param>
/// <returns></returns>
public static Matrix3D TryTransformTo2DAncestor(DependencyObject visual, out Viewport3DVisual viewport, out bool success)
{
Matrix3D to2D = GetWorldTransformationMatrix(visual, out viewport);
to2D.Append(MUtils.TryWorldToViewportTransform(viewport, out success));
if (!success)
{
return(ZeroMatrix);
}
return(to2D);
}
/// <summary>
/// Computes the transform from world space to the Viewport3DVisual's
/// inner 2D space.
///
/// This method can fail if Camera.Transform is non-invertable
/// in which case the camera clip planes will be coincident and
/// nothing will render. In this case success will be false.
/// </summary>
public static Matrix3D TryWorldToViewportTransform(Viewport3DVisual visual, out bool success)
{
success = false;
Matrix3D result = TryWorldToCameraTransform(visual, out success);
if (success)
{
result.Append(GetProjectionMatrix(visual.Camera, MUtils.GetAspectRatio(visual.Viewport.Size)));
result.Append(GetHomogeneousToViewportTransform(visual.Viewport));
success = true;
}
return(result);
}
public Point?Point3DToScreen2D(Point3D point3D, Viewport3D viewPort)
{
// We need a Viewport3DVisual but we only have a Viewport3D.
if (viewPort.Children.Count == 0)
{
return(null);
}
Viewport3DVisual vpv = VisualTreeHelper.GetParent(viewPort.Children[0]) as Viewport3DVisual;
// Get the world to viewport transform matrix
Matrix3D m = MUtils.TryWorldToViewportTransform(vpv, out var bOk);
if (!bOk)
{
return(null);
}
// Transform the 3D point to 2D
var transformedPoint = m.Transform(point3D);
var screen2DPoint = new Point(transformedPoint.X, transformedPoint.Y);
return(screen2DPoint);
}
