hexahedron.h

/*****************************************************************************
 * VCLib                                                                     *
 * Visual Computing Library                                                  *
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 * Copyright(C) 2021-2025                                                    *
 * Visual Computing Lab                                                      *
 * ISTI - Italian National Research Council                                  *
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 * it under the terms of the Mozilla Public License Version 2.0 as published *
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 * This program is distributed in the hope that it will be useful,           *
 * but WITHOUT ANY WARRANTY; without even the implied warranty of            *
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the              *
 * Mozilla Public License Version 2.0                                        *
 * (https://www.mozilla.org/en-US/MPL/2.0/) for more details.                *
 ****************************************************************************/
 
#ifndef VCL_ALGORITHMS_MESH_CREATE_HEXAHEDRON_H
#define VCL_ALGORITHMS_MESH_CREATE_HEXAHEDRON_H
 
#include <vclib/mesh/requirements.h>
 
namespace vcl {
 
namespace detail {
 
template<FaceMeshConcept MeshType>
void fillHexahedronTriangles(MeshType& m)
{
    m.reserveFaces(12);
    m.addFace(0, 2, 1);
    m.addFace(3, 1, 2);
    m.addFace(0, 4, 2);
    m.addFace(6, 2, 4);
    m.addFace(0, 1, 4);
    m.addFace(5, 4, 1);
    m.addFace(7, 6, 5);
    m.addFace(4, 5, 6);
    m.addFace(7, 3, 6);
    m.addFace(2, 6, 3);
    m.addFace(7, 5, 3);
    m.addFace(1, 3, 5);
}
 
template<FaceMeshConcept MeshType>
void fillHexahedronQuads(MeshType& m)
{
    m.reserveFaces(6);
    m.addFace(2, 3, 1, 0);
    m.addFace(4, 6, 2, 0);
    m.addFace(1, 5, 4, 0);
    m.addFace(6, 4, 5, 7);
    m.addFace(3, 2, 6, 7);
    m.addFace(5, 1, 3, 7);
}
 
} // namespace detail
 
template<FaceMeshConcept MeshType>
MeshType createHexahedron()
{
    using CoordType = MeshType::Vertex::CoordType;
 
    return createHexahedron<MeshType>(
        CoordType(-1, -1, -1), CoordType(1, 1, 1));
}
 
template<FaceMeshConcept MeshType, Point3Concept CoordType>
MeshType createHexahedron(const CoordType& min, const CoordType& max)
{
    MeshType m;
 
    // fill vertices...
    m.addVertices(
        CoordType(min(0), min(1), min(2)),
        CoordType(max(0), min(1), min(2)),
        CoordType(min(0), max(1), min(2)),
        CoordType(max(0), max(1), min(2)),
        CoordType(min(0), min(1), max(2)),
        CoordType(max(0), min(1), max(2)),
        CoordType(min(0), max(1), max(2)),
        CoordType(max(0), max(1), max(2)));
 
    // fill faces
    if constexpr (HasTriangles<MeshType>) {
        detail::fillHexahedronTriangles(m);
    }
    else {
        detail::fillHexahedronQuads(m);
    }
    return m;
}
 
template<FaceMeshConcept MeshType, Point3Concept CoordType>
MeshType createCube(const CoordType& min, double edgeLength)
{
    return createHexahedron<MeshType>(min, CoordType(min + edgeLength));
}
 
template<FaceMeshConcept MeshType>
MeshType createCube()
{
    using CoordType = MeshType::Vertex::CoordType;
    return createCube<MeshType>(CoordType(-0.5, -0.5, -0.5), 1);
}
 
} // namespace vcl
 
#endif // VCL_ALGORITHMS_MESH_CREATE_HEXAHEDRON_H