// Helper method to prepend the inverse of Camera.Transform to the
// the given viewMatrix. This is used by the various GetViewMatrix()
// and RayFromViewportPoint implementations.
//
// Transforming the camera is equivalent to applying the inverse
// transform to the scene. We invert the transform and prepend it to
// the result of viewMatrix:
//
// -1
// viewMatrix = Camera.Transform x viewMatrix
//
// If the matrix is non-invertable we set the viewMatrix to NaNs which
// will result in nothing being rendered. This is the correct behavior
// since the near and far planes will have collapsed onto each other.
internal static void PrependInverseTransform(Matrix3D matrix, ref Matrix3D viewMatrix)
{
if (!matrix.InvertCore())
{
// If the matrix is non-invertable we return a NaN matrix.
viewMatrix = new Matrix3D(
double.NaN, double.NaN, double.NaN, double.NaN,
double.NaN, double.NaN, double.NaN, double.NaN,
double.NaN, double.NaN, double.NaN, double.NaN,
double.NaN, double.NaN, double.NaN, double.NaN);
}
else
{
viewMatrix.Prepend(matrix);
}
}
// Helper method to prepend the inverse of Camera.Transform to the
// the given viewMatrix. This is used by the various GetViewMatrix()
// and RayFromViewportPoint implementations.
//
// Transforming the camera is equivalent to applying the inverse
// transform to the scene. We invert the transform and prepend it to
// the result of viewMatrix:
//
// -1
// viewMatrix = Camera.Transform x viewMatrix
//
// If the matrix is non-invertable we set the viewMatrix to NaNs which
// will result in nothing being rendered. This is the correct behavior
// since the near and far planes will have collapsed onto each other.
internal static void PrependInverseTransform(Matrix3D matrix, ref Matrix3D viewMatrix)
{
if (!matrix.InvertCore())
{
// If the matrix is non-invertable we return a NaN matrix.
viewMatrix = new Matrix3D(
double.NaN, double.NaN, double.NaN, double.NaN,
double.NaN, double.NaN, double.NaN, double.NaN,
double.NaN, double.NaN, double.NaN, double.NaN,
double.NaN, double.NaN, double.NaN, double.NaN);
}
else
{
viewMatrix.Prepend(matrix);
}
}
public static void Transform(Matrix3D modelMatrix,
ref Point3D origin, ref Vector3D direction, out bool isRay)
{
if (modelMatrix.InvertCore())
{
Point4D o = new Point4D(origin.X,origin.Y,origin.Z,1);
Point4D d = new Point4D(direction.X,direction.Y,direction.Z,0);
modelMatrix.MultiplyPoint(ref o);
modelMatrix.MultiplyPoint(ref d);
if (o.W == 1 && d.W == 0)
{
// Affine transformation
origin = new Point3D(o.X, o.Y, o.Z);
direction = new Vector3D(d.X, d.Y, d.Z);
isRay = true;
}
else
{
// Non-affine transformation (likely projection)
// Form 4x2 matrix with two points on line in two columns.
double[,] linepoints = new double[,]{{o.X,d.X},{o.Y,d.Y},{o.Z,d.Z},{o.W,d.W}};
ColumnsToAffinePointVector(linepoints,0,1,out origin, out direction);
isRay = false;
}
}
else
{
TransformSingular(ref modelMatrix, ref origin, ref direction);
isRay = false;
}
}