// Two CreateRotation functions below are adapted from the implementation of getRotation in
// the VisualizationLibrary SDK (sources at http://visualizationlibrary.org/ )
/// <summary>
/// Creates a rotation matrix converting from a starting direction to a desired direction.
/// </summary>
/// <param name="fromDirection">Starting direction</param>
/// <param name="toDirection">Desired direction</param>
/// <returns>the matrix that applied to <see paramref="fromDirection"/> results in <see paramref="toDirection"/></returns>
public static XbimMatrix3D CreateRotation(XbimPoint3D fromDirection, XbimPoint3D toDirection)
{
var a = new XbimVector3D(toDirection.X, toDirection.Y, toDirection.Z);
var b = new XbimVector3D(fromDirection.X, fromDirection.Y, fromDirection.Z);
a = a.Normalized();
b = b.Normalized();
double cosa = a.DotProduct(b);
cosa = clamp(cosa, -1, +1);
var axis = XbimVector3D.CrossProduct(a, b).Normalized();
double alpha = Math.Acos(cosa);
return(CreateRotation(alpha, axis));
}
// Microsoft.Xna.Framework.Matrix
public static XbimMatrix3D CreateLookAt(XbimVector3D cameraPosition, XbimVector3D cameraTarget, XbimVector3D cameraUpVector)
{
// prepare vectors
XbimVector3D vector = cameraPosition - cameraTarget;
vector.Normalized();
XbimVector3D vector2 = XbimVector3D.CrossProduct(cameraUpVector, vector);
vector2.Normalized();
XbimVector3D vector3 = XbimVector3D.CrossProduct(vector, vector2);
// prepare matrix
XbimMatrix3D result = new XbimMatrix3D(
vector2.X, vector3.X, vector.X, 0.0,
vector2.Y, vector3.Y, vector.Y, 0.0,
vector2.Z, vector3.Z, vector.Z, 0.0,
-XbimVector3D.DotProduct(vector2, cameraPosition), -XbimVector3D.DotProduct(vector3, cameraPosition), -XbimVector3D.DotProduct(vector, cameraPosition), 1.0);
return(result);
}
public double DotProduct(XbimVector3D v2)
{
return(XbimVector3D.DotProduct(this, v2));
}
