Method OffsetPoint

CPP/Clipper2Lib/src/clipper.offset.cpp:311–370

}

void ClipperOffset::OffsetPoint(Group& group, const Path64& path, size_t j, size_t k)
{
	// Let A = change in angle where edges join
	// A == 0: ie no change in angle (flat join)
	// A == PI: edges 'spike'
	// sin(A) < 0: right turning
	// cos(A) < 0: change in angle is more than 90 degree

	if (path[j] == path[k]) return;

	double sin_a = CrossProduct(norms[j], norms[k]);
	double cos_a = DotProduct(norms[j], norms[k]);
	if (sin_a > 1.0) sin_a = 1.0;
	else if (sin_a < -1.0) sin_a = -1.0;

	if (deltaCallback64_) {
		group_delta_ = deltaCallback64_(path, norms, j, k);
		if (group.is_reversed) group_delta_ = -group_delta_;
	}
	if (std::fabs(group_delta_) <= floating_point_tolerance)
	{
        path_out.emplace_back(path[j]);
		return;
	}

	if (cos_a > -0.999 && (sin_a * group_delta_ < 0)) // test for concavity first (#593)
	{
		// is concave
		// by far the simplest way to construct concave joins, especially those joining very 
		// short segments, is to insert 3 points that produce negative regions. These regions 
		// will be removed later by the finishing union operation. This is also the best way 
		// to ensure that path reversals (ie over-shrunk paths) are removed.
#ifdef USINGZ
        path_out.emplace_back(GetPerpendic(path[j], norms[k], group_delta_), path[j].z);
        path_out.emplace_back(path[j]); // (#405, #873, #916)
        path_out.emplace_back(GetPerpendic(path[j], norms[j], group_delta_), path[j].z);
#else
        path_out.emplace_back(GetPerpendic(path[j], norms[k], group_delta_));
        path_out.emplace_back(path[j]); // (#405, #873, #916)
        path_out.emplace_back(GetPerpendic(path[j], norms[j], group_delta_));
#endif
	}
	else if (cos_a > 0.999 && join_type_ != JoinType::Round)
	{
		// almost straight - less than 2.5 degree (#424, #482, #526 & #724)
		DoMiter(path, j, k, cos_a);
	}
	else if (join_type_ == JoinType::Miter)
	{
		// miter unless the angle is sufficiently acute to exceed ML
		if (cos_a > temp_lim_ - 1) DoMiter(path, j, k, cos_a);
		else DoSquare(path, j, k);
	}
	else if (join_type_ == JoinType::Round)
		DoRound(path, j, k, std::atan2(sin_a, cos_a));
	else if ( join_type_ == JoinType::Bevel)
		DoBevel(path, j, k);
	else