/// <summary>
/// Gets the hit point on that plane of the active layer rectangle, that is facing the camera.
/// </summary>
/// <param name="doc">The graph document containing the active layer.</param>
/// <param name="activeLayer">The active layer of the graph document.</param>
/// <param name="hitposition">Hit point in relative screen coordinates. The z-component is the aspect ratio of the screen (y/x).</param>
/// <param name="hitPointOnPlaneInActiveLayerCoordinates">Output: The hit point on the plane of the active layer that faces the camera. The hit point is returned in active layer coordinates.</param>
/// <param name="rotationsRadian">The rotation angles that can be used e.g. to orient text so that the text is most readable from the current camera setting. Rotation angle around x is the x-component of the returned vector, and so on.</param>
/// <exception cref="InvalidProgramException">There should always be a plane of a rectangle that can be hit!</exception>
public static void GetHitPointOnActiveLayerPlaneFacingTheCamera(GraphDocument doc, HostLayer activeLayer, PointD3D hitposition, out PointD3D hitPointOnPlaneInActiveLayerCoordinates, out VectorD3D rotationsRadian)
{
var activeLayerTransformation = activeLayer.TransformationFromRootToHere();
var camera = doc.Camera;
var hitData = new HitTestPointData(camera.GetHitRayMatrix(hitposition));
hitData = hitData.NewFromAdditionalTransformation(activeLayerTransformation); // now hitdata are in layer cos
var targetToEye = hitData.WorldTransformation.Transform(camera.TargetToEyeVectorNormalized); // targetToEye in layer coordinates
var upEye = hitData.WorldTransformation.Transform(camera.UpVectorPerpendicularToEyeVectorNormalized); // camera up vector in layer coordinates
// get the face which has the best dot product between the eye vector of the camera and the plane's normal
var layerRect = new RectangleD3D(PointD3D.Empty, activeLayer.Size);
double maxval = double.MinValue;
PlaneD3D maxPlane = PlaneD3D.Empty;
foreach (var plane in layerRect.Planes)
{
double val = VectorD3D.DotProduct(plane.Normal, targetToEye);
if (val > maxval)
{
maxval = val;
maxPlane = plane;
}
}
bool isHit = hitData.IsPlaneHitByRay(maxPlane, out hitPointOnPlaneInActiveLayerCoordinates); // hitPointOnPlane is in layer coordinates too
if (!isHit)
throw new InvalidProgramException("There should always be a plane of a rectangle that can be hit!");
VectorD3D zaxis = maxPlane.Normal;
VectorD3D yaxis = upEye;
// Find y axis perpendicular to zaxis
maxval = double.MinValue;
foreach (var plane in layerRect.Planes)
{
double val = VectorD3D.DotProduct(plane.Normal, upEye);
if (val > maxval && 0 == VectorD3D.DotProduct(plane.Normal, zaxis))
{
maxval = val;
yaxis = plane.Normal;
}
}
var xaxis = VectorD3D.CrossProduct(yaxis, zaxis);
// now we have all information about the spatial position and orientation of the text:
// hitPointOnPlane is the position of the text
// maxPlane.Normal is the face orientation of the text
// maxUpVector is the up orientation of the text
double cx, sx, cy, sy, cz, sz;
sy = xaxis.Z;
if (1 != Math.Abs(sy))
{
cy = Math.Sqrt(1 - sy * sy);
cz = xaxis.X / cy;
sz = xaxis.Y / cy;
sx = yaxis.Z / cy;
cx = zaxis.Z / cy;
}
else // sy is +1, thus cy is zero
{
// we set x-rotation to zero, i.e. cx==1 and sx==0
cy = 0;
cx = 1;
sx = 0;
cz = yaxis.Y;
sz = -yaxis.X;
}
rotationsRadian = new VectorD3D(Math.Atan2(sx, cx), Math.Atan2(sy, cy), Math.Atan2(sz, cz));
}
/// <summary>
/// Gets the principal coordinate system that results of the camera facing a layer. The plane of the layer that best faced the camera is used for the calculations.
/// The normal of that layer is returned as z-axis, the vector that best matches the up-vector of the camera is becoming the y-axis,
/// and the x-axis results from the z-axis and the y-axis.
/// </summary>
/// <param name="camera">The camera.</param>
/// <param name="activeLayer">The active layer of the graph document.</param>
/// <param name="transformation">Matrix that contains the principal axes as described above. The axes coordinates are in the coordinates of the layer provided in the argument <paramref name="activeLayer"/>.</param>
/// <exception cref="InvalidProgramException">There should always be a plane of a rectangle that can be hit!</exception>
public static void GetCoordinateSystemBasedOnLayerPlaneFacingTheCamera(CameraBase camera, HostLayer activeLayer, out Matrix3x3 transformation)
{
PointD3D hitposition = new PointD3D(0.5, 0.5, 1); // this hit position is arbitrary, every other position should work similarly
var activeLayerTransformation = activeLayer.TransformationFromRootToHere();
var hitData = new HitTestPointData(camera.GetHitRayMatrix(hitposition));
hitData = hitData.NewFromAdditionalTransformation(activeLayerTransformation); // now hitdata are in layer cos
var targetToEye = hitData.WorldTransformation.Transform(camera.TargetToEyeVectorNormalized); // targetToEye in layer coordinates
var upEye = hitData.WorldTransformation.Transform(camera.UpVectorPerpendicularToEyeVectorNormalized); // camera up vector in layer coordinates
// get the face which has the best dot product between the eye vector of the camera and the plane's normal
var layerRect = new RectangleD3D(PointD3D.Empty, activeLayer.Size);
double maxval = double.MinValue;
PlaneD3D maxPlane = PlaneD3D.Empty;
foreach (var plane in layerRect.Planes)
{
double val = VectorD3D.DotProduct(plane.Normal, targetToEye);
if (val > maxval)
{
maxval = val;
maxPlane = plane;
}
}
// bool isHit = hitData.IsPlaneHitByRay(maxPlane, out hitPointOnPlaneInActiveLayerCoordinates); // hitPointOnPlane is in layer coordinates too
// if (!isHit)
// throw new InvalidProgramException("There should always be a plane of a rectangle that can be hit!");
VectorD3D zaxis = maxPlane.Normal;
VectorD3D yaxis = upEye;
// Find y axis perpendicular to zaxis
maxval = double.MinValue;
foreach (var plane in layerRect.Planes)
{
double val = VectorD3D.DotProduct(plane.Normal, upEye);
if (val > maxval && 0 == VectorD3D.DotProduct(plane.Normal, zaxis))
{
maxval = val;
yaxis = plane.Normal;
}
}
var xaxis = VectorD3D.CrossProduct(yaxis, zaxis);
// now we have all information about the spatial position and orientation of the text:
// hitPointOnPlane is the position of the text
// maxPlane.Normal is the face orientation of the text
// maxUpVector is the up orientation of the text
xaxis = xaxis.Normalized;
yaxis = yaxis.Normalized;
zaxis = zaxis.Normalized;
transformation = new Matrix3x3(
xaxis.X, yaxis.X, zaxis.X,
xaxis.Y, yaxis.Y, zaxis.Y,
xaxis.Z, yaxis.Z, zaxis.Z
);
}