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// ************************************************************************************************
//
// BornAgain: simulate and fit reflection and scattering
//
//! @file Img3D/Mesh/Cuboctahedron.cpp
//! @brief Implements utility functions in ba3d namespace.
//!
//! @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 "Base/Util/Assert.h"
#include "Img3D/Model/Geometry.h"
#include <numbers>
using std::numbers::pi;
namespace Img3D {
Geometry::Mesh Geometry::meshBipyramid4(float rH, float alpha, float H)
{ // t/D
// alpha is the angle between the common square interface and one of the side faces (alpha for
// both the two truncated pyramids is the same)
// H here is the normalized height of the cuboctahedron i.e. H/L (see particles.cpp)
ASSERT(alpha <= float((pi / 2)));
ASSERT(rH >= 0);
float const D = .5f, t = tanf(float((pi / 2)) - alpha);
float const Db = D - t * H, Dt = D - t * rH * H;
Vertices vs_;
vs_.reserve(12);
float z[] = {0, H, H * (rH + 1)},
d[] = {Db, D, Dt}; // keep bottom of the cuboctahedron in z=0 plane
for (int i = 0; i < 3; ++i)
for (int x : {-1, +1})
for (int y : {-1, +1}) {
float di = d[i];
vs_.append(F3(x * di, y * di, z[i]));
}
ASSERT(12 == vs_.count());
Vertices vs;
vs.reserve(60);
vs.addQuad(vs_, 0, 1, 3, 2);
vs.addQuad(vs_, 8, 10, 11, 9);
vs.addQuad(vs_, 0, 4, 5, 1);
vs.addQuad(vs_, 1, 5, 7, 3);
vs.addQuad(vs_, 3, 7, 6, 2);
vs.addQuad(vs_, 2, 6, 4, 0);
vs.addQuad(vs_, 4, 8, 9, 5);
vs.addQuad(vs_, 5, 9, 11, 7);
vs.addQuad(vs_, 7, 11, 10, 6);
vs.addQuad(vs_, 6, 10, 8, 4);
ASSERT(60 == vs.count());
return makeMesh(vs);
}
} // namespace Img3D
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