/// <summary>
/// Returns the brightness of the mess at a points position
/// </summary>
/// <returns></returns>
public double CalculatePointBrightness(Mesh mesh, Point3d p, IList<Color> colours)
{
double[] barycentricCoordinates = mesh.ClosestMeshPoint(p).T;
MeshFace face = mesh.Faces.GetFace(mesh.FaceIndexOfClosestPoint(p));
double brightnessVertexA = colours[face.A].GetBrightness() * barycentricCoordinates[0];
double brightnessVertexB = colours[face.B].GetBrightness() * barycentricCoordinates[1];
double brightnessVertexC = colours[face.C].GetBrightness() * barycentricCoordinates[2];
double brightnessVertexD = colours[face.D].GetBrightness() * barycentricCoordinates[3];
double brightness = brightnessVertexA + brightnessVertexB + brightnessVertexC + brightnessVertexD;
return brightness;
}