public static Envelope GetEnvelope(Geometry a, Geometry b, Envelope targetEnv)
{
var cec = new RobustClipEnvelopeComputer(targetEnv);
cec.Add(a);
cec.Add(b);
return(cec.Envelope);
}
/// <summary>
/// Computes a clipping envelope for overlay input geometries.
/// The clipping envelope encloses all geometry line segments which
/// might participate in the overlay, with a buffer to
/// account for numerical precision
/// (in particular, rounding due to a precision model.
/// The clipping envelope is used in both the <see cref="RingClipper"/>
/// and in the <see cref="LineLimiter"/>.
/// <para/>
/// Some overlay operations (i.e. <see cref="SpatialFunction.Union"/> and <see cref="SpatialFunction.SymDifference"/>)
/// cannot use clipping as an optimization,
/// since the result envelope is the full extent of the two input geometries.
/// In this case the returned
/// envelope is <c>null</c> to indicate this.
/// </summary>
/// <param name="opCode">The overlay op code</param>
/// <param name="inputGeom">The input geometries</param>
/// <param name="pm">The precision model being used</param>
/// <returns>An envelope for clipping and line limiting, or null if no clipping is performed</returns>
internal static Envelope ClippingEnvelope(SpatialFunction opCode, InputGeometry inputGeom, PrecisionModel pm)
{
var resultEnv = ResultEnvelope(opCode, inputGeom, pm);
if (resultEnv == null)
{
return(null);
}
var clipEnv = RobustClipEnvelopeComputer.GetEnvelope(
inputGeom.GetGeometry(0),
inputGeom.GetGeometry(1),
resultEnv);
var safeEnv = SafeEnv(clipEnv, pm);
return(safeEnv);
}
