/*private*/
bool
OffsetCurveSetBuilder::isErodedCompletely(CoordinateSequence *ringCoord,
double bufferDistance)
{
double minDiam=0.0;
// degenerate ring has no area
if (ringCoord->getSize() < 4)
return bufferDistance < 0;
// important test to eliminate inverted triangle bug
// also optimizes erosion test for triangles
if (ringCoord->getSize() == 4)
return isTriangleErodedCompletely(ringCoord, bufferDistance);
/**
* The following is a heuristic test to determine whether an
* inside buffer will be eroded completely->
* It is based on the fact that the minimum diameter of the ring
* pointset
* provides an upper bound on the buffer distance which would erode the
* ring->
* If the buffer distance is less than the minimum diameter, the ring
* may still be eroded, but this will be determined by
* a full topological computation->
*
*/
LinearRing *ring=inputGeom.getFactory()->createLinearRing(*ringCoord);
MinimumDiameter md(ring); //=new MinimumDiameter(ring);
minDiam=md.getLength();
delete ring;
//delete md;
//System->out->println(md->getDiameter());
return minDiam < (2 * fabs(bufferDistance));
}
/*private*/
bool
OffsetCurveSetBuilder::isErodedCompletely(const LinearRing *ring,
double bufferDistance)
{
const CoordinateSequence *ringCoord = ring->getCoordinatesRO();
// degenerate ring has no area
if (ringCoord->getSize() < 4)
return bufferDistance < 0;
// important test to eliminate inverted triangle bug
// also optimizes erosion test for triangles
if (ringCoord->getSize() == 4)
return isTriangleErodedCompletely(ringCoord, bufferDistance);
const Envelope* env = ring->getEnvelopeInternal();
double envMinDimension = std::min(env->getHeight(), env->getWidth());
if (bufferDistance < 0.0 && 2 * std::abs(bufferDistance) > envMinDimension)
return true;
/**
* The following is a heuristic test to determine whether an
* inside buffer will be eroded completely->
* It is based on the fact that the minimum diameter of the ring
* pointset
* provides an upper bound on the buffer distance which would erode the
* ring->
* If the buffer distance is less than the minimum diameter, the ring
* may still be eroded, but this will be determined by
* a full topological computation->
*
*/
/* MD 7 Feb 2005 - there's an unknown bug in the MD code,
so disable this for now */
#if 0
MinimumDiameter md(ring); //=new MinimumDiameter(ring);
double minDiam = md.getLength();
return minDiam < (2 * std::fabs(bufferDistance));
#endif
return false;
}
