C++ SplineSurface::coefs_begin方法代码示例

//==========================================================================
void GeometryTools::findDominant(const SplineSurface& surface,
		  Vector3D& dominant_u, Vector3D& dominant_v)
//==========================================================================
{
    int nu = surface.numCoefs_u();
    int nv = surface.numCoefs_v();
    vector<double>::const_iterator start = surface.coefs_begin();
    Vector3D temp;
    // Dominant in u-direction
    dominant_u = Vector3D(0.0, 0.0, 0.0);
    for (int j = 0; j < nv; ++j) {
	for (int dd = 0; dd < 3; ++dd) {
	    temp[dd] = *(start + 3*(nu*j + (nu-1)) + dd)
		- *(start + 3*(nu*j) + dd);
	}
	dominant_u += temp;
    }
    // Dominant in v-direction
    dominant_v = Vector3D(0.0, 0.0, 0.0);
    for (int i = 0; i < nu; ++i) {
	for (int dd = 0; dd < 3; ++dd) {
	    temp[dd] = *(start + 3*(nu*(nv-1) + i) + dd)
		- *(start + 3*i + dd);
	}
	dominant_v += temp;
    }

    return;
}

//===========================================================================
vector<shared_ptr<SplineSurface> >
SurfaceCreators::separateRationalParts(const SplineSurface& sf)
//===========================================================================
{
    bool rat = sf.rational();
    ASSERT(rat);

    int dim= sf.dimension();
    int rdim = dim + 1;
    vector<shared_ptr<SplineSurface> > sep_sfs;
    vector<double> coefs(sf.coefs_begin(), sf.coefs_end());
    int nmb1 = sf.numCoefs_u();
    int nmb2 = sf.numCoefs_v();
    vector<double> rcoefs;
    int num_coefs = nmb1*nmb2;
    vector<double>::const_iterator rcoef_iter = sf.rcoefs_begin();
    for (int ki = 0; ki < num_coefs; ++ki) {
	rcoefs.push_back(rcoef_iter[ki*rdim+1]);
	for (int kj = 0; kj < dim; ++kj) {
	    coefs[ki*dim+kj] /= (rcoefs.back());
	}
    }
    sep_sfs.push_back(shared_ptr<SplineSurface>
		      (new SplineSurface(nmb1, nmb2, sf.order_u(), sf.order_v(),
					 sf.basis_u().begin(), sf.basis_v().begin(),
					 coefs.begin(), dim)));
    sep_sfs.push_back(shared_ptr<SplineSurface>
		      (new SplineSurface(nmb1, nmb2, sf.order_u(), sf.order_v(),
					 sf.basis_u().begin(), sf.basis_v().begin(),
					 rcoefs.begin(), 1)));

    return sep_sfs;
}

//==========================================================================
void cart_to_bary(const SplineSurface& sf, const BaryCoordSystem3D& bc,
		  SplineSurface& sf_bc)
//==========================================================================
{
    ALWAYS_ERROR_IF(sf.dimension() != 3, "Dimension must be 3.");


    int nu = sf.numCoefs_u();
    int nv = sf.numCoefs_v();
    Vector3D cart;
    Vector4D bary;
    vector<double> new_coefs;
    if (!sf.rational()) {
	new_coefs.resize(4 * nu * nv);
	for (int iv = 0; iv < nv; ++iv) {
	    for (int iu = 0; iu < nu; ++iu) {
		int offset = nu * iv + iu;
		cart = Vector3D(sf.coefs_begin() + 3 * offset);
		bary = bc.cartToBary(cart);
		for (int j = 0; j < 4; ++j) {
		    new_coefs[4*offset + j] = bary[j];
		}
	    }
	}
    } else {
	new_coefs.resize(5 * nu * nv);
	for (int iv = 0; iv < nv; ++iv) {
	    for (int iu = 0; iu < nu; ++iu) {
		int offset = nu * iv + iu;
		cart = Vector3D(sf.coefs_begin() + 3 * offset);
		bary = bc.cartToBary(cart);
		double w = sf.rcoefs_begin()[4*offset + 3];
		for (int j = 0; j < 4; ++j) {
		    new_coefs[5*offset + j] = bary[j] * w;
		}
		new_coefs[5*offset + 4] = w;
	    }
	}
    }
    sf_bc = SplineSurface(nu, nv, sf.order_u(), sf.order_v(),
			  sf.basis_u().begin(), sf.basis_v().begin(),
			  new_coefs.begin(), 4, sf.rational());
    return;	
}

int main()
{
    ObjectHeader header;
    SplineSurface surf;
    cin >> header >> surf;

    PointCloud<3> cloud(surf.coefs_begin(),
                        surf.numCoefs_u()*surf.numCoefs_v());
    cloud.writeStandardHeader(cout);
    cout << cloud;
}

//==========================================================================
bool GeometryTools::negativeProj(const SplineSurface& surface,
		  const Array<Vector3D, 2>& refvector,
		  const double eps)
//==========================================================================
{
    int num_u = surface.numCoefs_u();
    int num_v = surface.numCoefs_v();
    Vector3D temp;
    int i = 0, j = 0;
    while (i < num_u-1) {
	j = 0;
	while (j < num_v) {
	    temp[0] = *(surface.coefs_begin() + 3*(num_u*j + i+1))
		- *(surface.coefs_begin() + 3*(num_u*j + i));
	    temp[1] = *(surface.coefs_begin() + 3*(num_u*j + i+1) + 1)
		- *(surface.coefs_begin() + 3*(num_u*j + i) + 1);
	    temp[2] = *(surface.coefs_begin() + 3*(num_u*j + i+1) + 2)
		- *(surface.coefs_begin() + 3*(num_u*j + i) + 2);
	    // Positive tolerance means that there must be a small
	    // _nonzero_ negative projection before it is reported as
	    // negative!
	    if (temp * refvector[0] < -eps)
		return true;
	    ++j;
	}
	++i;
    }
    i = 0;
    while (i < num_u) {
	j = 0;
	while (j < num_v-1) {
	    temp[0] = *(surface.coefs_begin() + 3*(num_u*(j+1) + i))
		- *(surface.coefs_begin() + 3*(num_u*j + i));
	    temp[1] = *(surface.coefs_begin() + 3*(num_u*(j+1) + i) + 1)
		- *(surface.coefs_begin() + 3*(num_u*j + i) +1);
	    temp[2] = *(surface.coefs_begin() + 3*(num_u*(j+1) + i) + 2)
		- *(surface.coefs_begin() + 3*(num_u*j + i) + 2);
	    // Positive tolerance means that there must be a small
	    // _nonzero_ negative projection before it is reported as
	    // negative!
	    if (temp * refvector[1] < -eps)
		return true;
	    ++j;
	}
	++i;
    }

    return false;
}

//===========================================================================
void SplineUtils::refinedBezierCoefsCubic(SplineSurface& spline_sf,
					  int ind_u_min, int ind_v_min,
					  vector<double>& bez_coefs)
//===========================================================================
{
    assert(!spline_sf.rational());

    if (bez_coefs.size() != 48)
	bez_coefs.resize(48);
    std::fill(bez_coefs.begin(), bez_coefs.end(), 0.0);

    // Values for inpute spline surface.
    int dim = spline_sf.dimension();
    int order_u = spline_sf.order_u();
    int order_v = spline_sf.order_u();
    int num_coefs_u = spline_sf.numCoefs_u();
    int num_coefs_v = spline_sf.numCoefs_v();

    // Checking that input index is within range.
    assert(ind_u_min >= order_u - 1 && ind_u_min < num_coefs_u);
    assert(ind_v_min >= order_v - 1 && ind_v_min < num_coefs_v);

    BsplineBasis& basis_u = spline_sf.basis_u();
    BsplineBasis& basis_v = spline_sf.basis_v();
    double* knot_u = &basis_u.begin()[0];
    double* knot_v = &basis_v.begin()[0];

    // We expect the knot index to refer to the last occurence.
    assert(knot_u[ind_u_min] != knot_u[ind_u_min+1]);
    assert(knot_v[ind_v_min] != knot_v[ind_v_min+1]);

    // We expect knot mult to be 1 or 4.
    int knot_mult_umin = (knot_u[ind_u_min-1] == knot_u[ind_u_min]) ? 4 : 1;
    int knot_mult_umax = (knot_u[ind_u_min+1] == knot_u[ind_u_min+2]) ? 4 : 1;
    int knot_mult_vmin = (knot_v[ind_v_min-1] == knot_v[ind_v_min]) ? 4 : 1;
    int knot_mult_vmax = (knot_v[ind_v_min+1] == knot_v[ind_v_min+2]) ? 4 : 1;

    bool kreg_at_ustart = (knot_mult_umin == 4);
    bool kreg_at_uend = (knot_mult_umax == 4);
    vector<double> transf_mat_u(16, 0.0);
    // if (!kreg_at_ustart && !kreg_at_uend)
    splineToBezierTransfMat(knot_u + ind_u_min - 3,
			    transf_mat_u);

#ifndef NDEBUG
    std::cout << "\ntransf_mat_u=" << std::endl;
    for (size_t kj = 0; kj < 4; ++kj)
    {
	for (size_t ki = 0; ki < 4; ++ki)
	    std::cout << transf_mat_u[kj*4+ki] << " ";
	std::cout << std::endl;
    }
    std::cout << std::endl;
#endif // NDEBUG

    // else
    // 	cubicTransfMat(knot_u + ind_u_min - 3,
    // 		       kreg_at_ustart, kreg_at_uend,
    // 		       transf_mat_u);

    bool kreg_at_vstart = (knot_mult_vmin == 4);
    bool kreg_at_vend = (knot_mult_vmax == 4);
    vector<double> transf_mat_v(16, 0.0);
    // if (!kreg_at_ustart && !kreg_at_uend)
    splineToBezierTransfMat(knot_v + ind_v_min - 3,
			    transf_mat_v);

#ifndef NDEBUG
    std::cout << "\ntransf_mat_v=" << std::endl;
    for (size_t kj = 0; kj < 4; ++kj)
    {
	for (size_t ki = 0; ki < 4; ++ki)
	    std::cout << transf_mat_v[kj*4+ki] << " ";
	std::cout << std::endl;
    }
    std::cout << std::endl;
#endif // NDEBUG

    extractBezierCoefs(&spline_sf.coefs_begin()[0],
		       num_coefs_u, num_coefs_v,
		       ind_u_min, ind_v_min,
		       transf_mat_u, transf_mat_v,
		       bez_coefs);

    return;
}