FormFactorFullSphere.cpp

//  ************************************************************************************************
//
//  BornAgain: simulate and fit reflection and scattering
//
//! @file      Sample/HardParticle/FormFactorFullSphere.cpp
//! @brief     Implements class FormFactorFullSphere.
//!
//! @homepage  http://www.bornagainproject.org
//! @license   GNU General Public License v3 or higher (see COPYING)
//! @copyright Forschungszentrum Jülich GmbH 2018
//! @authors   Scientific Computing Group at MLZ (see CITATION, AUTHORS)
//
//  ************************************************************************************************

#include "Sample/HardParticle/FormFactorFullSphere.h"
#include "Base/Math/Constants.h"
#include "Sample/HardParticle/FormFactorTruncatedSphere.h"
#include "Sample/LibFF/SomeFormFactors.h"
#include "Sample/Scattering/Rotations.h"

FormFactorFullSphere::FormFactorFullSphere(const std::vector<double> P, bool position_at_center)
    : IBornFF({"FullSphere", "sphere", {{"Radius", "nm", "radius", 0, +INF, 0}}}, P)
    , m_radius(m_P[0])
    , m_position_at_center(position_at_center)
{
}

FormFactorFullSphere::FormFactorFullSphere(double radius, bool position_at_center)
    : FormFactorFullSphere(std::vector<double>{radius}, position_at_center)
{
}

double FormFactorFullSphere::bottomZ(const IRotation* rotation) const
{
    if (m_position_at_center)
        return -m_radius;
    if (!rotation)
        return 0;
    R3 centre(0.0, 0.0, m_radius);
    R3 new_centre = rotation->transformed(centre);
    return new_centre.z() - m_radius;
}

double FormFactorFullSphere::topZ(const IRotation* rotation) const
{
    if (m_position_at_center)
        return m_radius;
    if (!rotation)
        return 2*m_radius;
    R3 centre(0.0, 0.0, m_radius);
    R3 new_centre = rotation->transformed(centre);
    return new_centre.z() + m_radius;
}

complex_t FormFactorFullSphere::formfactor(C3 q) const
{
    complex_t ret = SampleUtils::someff::ffSphere(q, m_radius);
    if (!m_position_at_center)
        ret *= exp_I(q.z() * m_radius);
    return ret;
}

IFormFactor* FormFactorFullSphere::sliceFormFactor(ZLimits limits, const IRotation* rotation,
                                                   R3 translation) const
{
    R3 new_translation = translation;
    if (rotation) {
        R3 center(0.0, 0.0, m_radius);
        new_translation += rotation->transformed(center) - center;
    }
    double height = 2.0 * m_radius;
    auto effects = computeSlicingEffects(limits, new_translation, height);
    FormFactorTruncatedSphere slicedff(m_radius, height - effects.dz_bottom, effects.dz_top);
    return createTransformedFormFactor(slicedff, nullptr, effects.position);
}