static void laplacianDeformPreview(LaplacianSystem *sys, float (*vertexCos)[3])
{
	int vid, i, j, n, na;
	n = sys->total_verts;
	na = sys->total_anchors;

#ifdef OPENNL_THREADING_HACK
	modifier_opennl_lock();
#endif

	if (!sys->is_matrix_computed) {
		nlNewContext();
		sys->context = nlGetCurrent();

		nlSolverParameteri(NL_NB_VARIABLES, n);
		nlSolverParameteri(NL_SYMMETRIC, NL_FALSE);
		nlSolverParameteri(NL_LEAST_SQUARES, NL_TRUE);
		nlSolverParameteri(NL_NB_ROWS, n + na);
		nlSolverParameteri(NL_NB_RIGHT_HAND_SIDES, 3);
		nlBegin(NL_SYSTEM);
		for (i = 0; i < n; i++) {
			nlSetVariable(0, i, sys->co[i][0]);
			nlSetVariable(1, i, sys->co[i][1]);
			nlSetVariable(2, i, sys->co[i][2]);
		}
		for (i = 0; i < na; i++) {
			vid = sys->index_anchors[i];
			nlSetVariable(0, vid, vertexCos[vid][0]);
			nlSetVariable(1, vid, vertexCos[vid][1]);
			nlSetVariable(2, vid, vertexCos[vid][2]);
		}
		nlBegin(NL_MATRIX);

		initLaplacianMatrix(sys);
		computeImplictRotations(sys);

		for (i = 0; i < n; i++) {
			nlRightHandSideSet(0, i, sys->delta[i][0]);
			nlRightHandSideSet(1, i, sys->delta[i][1]);
			nlRightHandSideSet(2, i, sys->delta[i][2]);
		}
		for (i = 0; i < na; i++) {
			vid = sys->index_anchors[i];
			nlRightHandSideSet(0, n + i, vertexCos[vid][0]);
			nlRightHandSideSet(1, n + i, vertexCos[vid][1]);
			nlRightHandSideSet(2, n + i, vertexCos[vid][2]);
			nlMatrixAdd(n + i, vid, 1.0f);
		}
		nlEnd(NL_MATRIX);
		nlEnd(NL_SYSTEM);
		if (nlSolveAdvanced(NULL, NL_TRUE)) {
			sys->has_solution = true;

			for (j = 1; j <= sys->repeat; j++) {
				nlBegin(NL_SYSTEM);
				nlBegin(NL_MATRIX);
				rotateDifferentialCoordinates(sys);

				for (i = 0; i < na; i++) {
					vid = sys->index_anchors[i];
					nlRightHandSideSet(0, n + i, vertexCos[vid][0]);
					nlRightHandSideSet(1, n + i, vertexCos[vid][1]);
					nlRightHandSideSet(2, n + i, vertexCos[vid][2]);
				}

				nlEnd(NL_MATRIX);
				nlEnd(NL_SYSTEM);
				if (!nlSolveAdvanced(NULL, NL_FALSE)) {
					sys->has_solution = false;
					break;
				}
			}
			if (sys->has_solution) {
				for (vid = 0; vid < sys->total_verts; vid++) {
					vertexCos[vid][0] = nlGetVariable(0, vid);
					vertexCos[vid][1] = nlGetVariable(1, vid);
					vertexCos[vid][2] = nlGetVariable(2, vid);
				}
			}
			else {
				sys->has_solution = false;
			}

		}
		else {
			sys->has_solution = false;
		}
		sys->is_matrix_computed = true;

	}
	else if (sys->has_solution) {
		nlBegin(NL_SYSTEM);
		nlBegin(NL_MATRIX);

		for (i = 0; i < n; i++) {
			nlRightHandSideSet(0, i, sys->delta[i][0]);
			nlRightHandSideSet(1, i, sys->delta[i][1]);
			nlRightHandSideSet(2, i, sys->delta[i][2]);
		}
		for (i = 0; i < na; i++) {
			vid = sys->index_anchors[i];
			nlRightHandSideSet(0, n + i, vertexCos[vid][0]);
			nlRightHandSideSet(1, n + i, vertexCos[vid][1]);
			nlRightHandSideSet(2, n + i, vertexCos[vid][2]);
			nlMatrixAdd(n + i, vid, 1.0f);
		}

		nlEnd(NL_MATRIX);
		nlEnd(NL_SYSTEM);
		if (nlSolveAdvanced(NULL, NL_FALSE)) {
			sys->has_solution = true;
			for (j = 1; j <= sys->repeat; j++) {
				nlBegin(NL_SYSTEM);
				nlBegin(NL_MATRIX);
				rotateDifferentialCoordinates(sys);

				for (i = 0; i < na; i++) {
					vid = sys->index_anchors[i];
					nlRightHandSideSet(0, n + i, vertexCos[vid][0]);
					nlRightHandSideSet(1, n + i, vertexCos[vid][1]);
					nlRightHandSideSet(2, n + i, vertexCos[vid][2]);
				}
				nlEnd(NL_MATRIX);
				nlEnd(NL_SYSTEM);
				if (!nlSolveAdvanced(NULL, NL_FALSE)) {
					sys->has_solution = false;
					break;
				}
			}
			if (sys->has_solution) {
				for (vid = 0; vid < sys->total_verts; vid++) {
					vertexCos[vid][0] = nlGetVariable(0, vid);
					vertexCos[vid][1] = nlGetVariable(1, vid);
					vertexCos[vid][2] = nlGetVariable(2, vid);
				}
			}
			else {
				sys->has_solution = false;
			}
		}
		else {
			sys->has_solution = false;
		}
	}

#ifdef OPENNL_THREADING_HACK
	modifier_opennl_unlock();
#endif
}
static void laplaciansmoothModifier_do(
        LaplacianSmoothModifierData *smd, Object *ob, DerivedMesh *dm,
        float (*vertexCos)[3], int numVerts)
{
	LaplacianSystem *sys;
	MDeformVert *dvert = NULL;
	MDeformVert *dv = NULL;
	float w, wpaint;
	int i, iter;
	int defgrp_index;

	DM_ensure_tessface(dm);

	sys = init_laplacian_system(dm->getNumEdges(dm), dm->getNumTessFaces(dm), numVerts);
	if (!sys) {
		return;
	}

	sys->mfaces = dm->getTessFaceArray(dm);
	sys->medges = dm->getEdgeArray(dm);
	sys->vertexCos = vertexCos;
	sys->min_area = 0.00001f;
	modifier_get_vgroup(ob, dm, smd->defgrp_name, &dvert, &defgrp_index);

	sys->vert_centroid[0] = 0.0f;
	sys->vert_centroid[1] = 0.0f;
	sys->vert_centroid[2] = 0.0f;
	memset_laplacian_system(sys, 0);

#ifdef OPENNL_THREADING_HACK
	modifier_opennl_lock();
#endif

	nlNewContext();
	sys->context = nlGetCurrent();
	nlSolverParameteri(NL_NB_VARIABLES, numVerts);
	nlSolverParameteri(NL_LEAST_SQUARES, NL_TRUE);
	nlSolverParameteri(NL_NB_ROWS, numVerts);
	nlSolverParameteri(NL_NB_RIGHT_HAND_SIDES, 3);

	init_laplacian_matrix(sys);

	for (iter = 0; iter < smd->repeat; iter++) {
		nlBegin(NL_SYSTEM);
		for (i = 0; i < numVerts; i++) {
			nlSetVariable(0, i, vertexCos[i][0]);
			nlSetVariable(1, i, vertexCos[i][1]);
			nlSetVariable(2, i, vertexCos[i][2]);
			if (iter == 0) {
				add_v3_v3(sys->vert_centroid, vertexCos[i]);
			}
		}
		if (iter == 0 && numVerts > 0) {
			mul_v3_fl(sys->vert_centroid, 1.0f / (float)numVerts);
		}

		nlBegin(NL_MATRIX);
		dv = dvert;
		for (i = 0; i < numVerts; i++) {
			nlRightHandSideSet(0, i, vertexCos[i][0]);
			nlRightHandSideSet(1, i, vertexCos[i][1]);
			nlRightHandSideSet(2, i, vertexCos[i][2]);
			if (iter == 0) {
				if (dv) {
					wpaint = defvert_find_weight(dv, defgrp_index);
					dv++;
				}
				else {
					wpaint = 1.0f;
				}

				if (sys->zerola[i] == 0) {
					if (smd->flag & MOD_LAPLACIANSMOOTH_NORMALIZED) {
						w = sys->vweights[i];
						sys->vweights[i] = (w == 0.0f) ? 0.0f : -fabsf(smd->lambda) * wpaint / w;
						w = sys->vlengths[i];
						sys->vlengths[i] = (w == 0.0f) ? 0.0f : -fabsf(smd->lambda_border) * wpaint * 2.0f / w;
						if (sys->numNeEd[i] == sys->numNeFa[i]) {
							nlMatrixAdd(i, i,  1.0f + fabsf(smd->lambda) * wpaint);
						}
						else {
							nlMatrixAdd(i, i,  1.0f + fabsf(smd->lambda_border) * wpaint * 2.0f);
						}
					}
					else {
						w = sys->vweights[i] * sys->ring_areas[i];
						sys->vweights[i] = (w == 0.0f) ? 0.0f : -fabsf(smd->lambda) * wpaint / (4.0f * w);
						w = sys->vlengths[i];
						sys->vlengths[i] = (w == 0.0f) ? 0.0f : -fabsf(smd->lambda_border) * wpaint * 2.0f / w;

						if (sys->numNeEd[i] == sys->numNeFa[i]) {
							nlMatrixAdd(i, i,  1.0f + fabsf(smd->lambda) * wpaint / (4.0f * sys->ring_areas[i]));
						}
						else {
							nlMatrixAdd(i, i,  1.0f + fabsf(smd->lambda_border) * wpaint * 2.0f);
						}
					}
				}
				else {
					nlMatrixAdd(i, i, 1.0f);
				}
			}
		}

		if (iter == 0) {
			fill_laplacian_matrix(sys);
		}

		nlEnd(NL_MATRIX);
		nlEnd(NL_SYSTEM);

		if (nlSolveAdvanced(NULL, NL_TRUE)) {
			validate_solution(sys, smd->flag, smd->lambda, smd->lambda_border);
		}
	}
	nlDeleteContext(sys->context);
	sys->context = NULL;

#ifdef OPENNL_THREADING_HACK
	modifier_opennl_unlock();
#endif

	delete_laplacian_system(sys);
}
static void rotateDifferentialCoordinates(LaplacianSystem *sys)
{
	float alpha, beta, gamma;
	float pj[3], ni[3], di[3];
	float uij[3], dun[3], e2[3], pi[3], fni[3], vn[4][3];
	int i, j, lvin, num_fni, k, fi;
	int *fidn;

	for (i = 0; i < sys->total_verts; i++) {
		copy_v3_v3(pi, sys->co[i]);
		copy_v3_v3(ni, sys->no[i]);
		k = sys->unit_verts[i];
		copy_v3_v3(pj, sys->co[k]);
		sub_v3_v3v3(uij, pj, pi);
		mul_v3_v3fl(dun, ni, dot_v3v3(uij, ni));
		sub_v3_v3(uij, dun);
		normalize_v3(uij);
		cross_v3_v3v3(e2, ni, uij);
		copy_v3_v3(di, sys->delta[i]);
		alpha = dot_v3v3(ni, di);
		beta = dot_v3v3(uij, di);
		gamma = dot_v3v3(e2, di);

		pi[0] = nlGetVariable(0, i);
		pi[1] = nlGetVariable(1, i);
		pi[2] = nlGetVariable(2, i);
		zero_v3(ni);
		num_fni = 0;
		num_fni = sys->ringf_map[i].count;
		for (fi = 0; fi < num_fni; fi++) {
			const unsigned int *vin;
			fidn = sys->ringf_map[i].indices;
			vin = sys->faces[fidn[fi]];
			lvin = vin[3] ? 4 : 3;
			for (j = 0; j < lvin; j++) {
				vn[j][0] = nlGetVariable(0, vin[j]);
				vn[j][1] = nlGetVariable(1, vin[j]);
				vn[j][2] = nlGetVariable(2, vin[j]);
				if (vin[j] == sys->unit_verts[i]) {
					copy_v3_v3(pj, vn[j]);
				}
			}

			if (lvin == 3) {
				normal_tri_v3(fni, vn[0], vn[1], vn[2]);
			}
			else if (lvin == 4) {
				normal_quad_v3(fni, vn[0], vn[1], vn[2], vn[3]);
			}
			add_v3_v3(ni, fni);
		}

		normalize_v3(ni);
		sub_v3_v3v3(uij, pj, pi);
		mul_v3_v3fl(dun, ni, dot_v3v3(uij, ni));
		sub_v3_v3(uij, dun);
		normalize_v3(uij);
		cross_v3_v3v3(e2, ni, uij);
		fni[0] = alpha * ni[0] + beta * uij[0] + gamma * e2[0];
		fni[1] = alpha * ni[1] + beta * uij[1] + gamma * e2[1];
		fni[2] = alpha * ni[2] + beta * uij[2] + gamma * e2[2];

		if (len_squared_v3(fni) > FLT_EPSILON) {
			nlRightHandSideSet(0, i, fni[0]);
			nlRightHandSideSet(1, i, fni[1]);
			nlRightHandSideSet(2, i, fni[2]);
		}
		else {
			nlRightHandSideSet(0, i, sys->delta[i][0]);
			nlRightHandSideSet(1, i, sys->delta[i][1]);
			nlRightHandSideSet(2, i, sys->delta[i][2]);
		}
	}
}