geometry.h

/*****************************************************************************
 * VCLib                                                                     *
 * Visual Computing Library                                                  *
 *                                                                           *
 * Copyright(C) 2021-2025                                                    *
 * Visual Computing Lab                                                      *
 * ISTI - Italian National Research Council                                  *
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 * This program is free software; you can redistribute it and/or modify      *
 * it under the terms of the Mozilla Public License Version 2.0 as published *
 * by the Mozilla Foundation; either version 2 of the License, or            *
 * (at your option) any later version.                                       *
 *                                                                           *
 * 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_MESH_ELEM_ALGORITHMS_POLYGON_GEOMETRY_H
#define VCL_MESH_ELEM_ALGORITHMS_POLYGON_GEOMETRY_H
 
#include <vclib/mesh/elements.h>
#include <vclib/mesh/views/components.h>
 
#include <vclib/space/core.h>
 
namespace vcl {
 
template<FaceConcept FaceType>
typename FaceType::VertexType::PositionType faceNormal(const FaceType& f)
{
    using PositionType = FaceType::VertexType::PositionType;
    if constexpr (TriangleFaceConcept<FaceType>) {
        return Triangle<PositionType>::normal(
            f.vertex(0)->position(),
            f.vertex(1)->position(),
            f.vertex(2)->position());
    }
    else {
        if (f.vertexNumber() == 3) {
            return Triangle<PositionType>::normal(
                f.vertex(0)->position(),
                f.vertex(1)->position(),
                f.vertex(2)->position());
        }
        else {
            return Polygon<PositionType>::normal(
                f.vertices() | views::positions);
        }
    }
}
 
template<FaceConcept FaceType>
typename FaceType::VertexType::PositionType faceBarycenter(const FaceType& f)
{
    using PositionType = FaceType::VertexType::PositionType;
    if constexpr (TriangleFaceConcept<FaceType>) {
        return Triangle<PositionType>::barycenter(
            f.vertex(0)->position(),
            f.vertex(1)->position(),
            f.vertex(2)->position());
    }
    else {
        return Polygon<PositionType>::barycenter(
            f.vertices() | views::positions);
    }
}
 
template<FaceConcept FaceType>
auto faceArea(const FaceType& f)
{
    using PositionType = FaceType::VertexType::PositionType;
    if constexpr (TriangleFaceConcept<FaceType>) {
        return Triangle<PositionType>::area(
            f.vertex(0)->position(),
            f.vertex(1)->position(),
            f.vertex(2)->position());
    }
    else {
        if (f.vertexNumber() == 3) {
            return Triangle<PositionType>::area(
                f.vertex(0)->position(),
                f.vertex(1)->position(),
                f.vertex(2)->position());
        }
        else {
            return Polygon<PositionType>::area(f.vertices() | views::positions);
        }
    }
}
 
template<FaceConcept FaceType>
auto facePerimeter(const FaceType& f)
{
    using PositionType = FaceType::VertexType::PositionType;
    if constexpr (TriangleFaceConcept<FaceType>) {
        return Triangle<PositionType>::perimeter(
            f.vertex(0)->position(),
            f.vertex(1)->position(),
            f.vertex(2)->position());
    }
    else {
        if (f.vertexNumber() == 3) {
            return Triangle<PositionType>::perimeter(
                f.vertex(0)->position(),
                f.vertex(1)->position(),
                f.vertex(2)->position());
        }
        else {
            return Polygon<PositionType>::perimeter(
                f.vertices() | views::positions);
        }
    }
}
 
template<FaceConcept FaceType>
auto faceAngleOnVertexRad(const FaceType& f, uint vi)
{
    const auto& p0 = f.vertex(vi)->position();
    const auto& p1 = f.vertexMod((int) vi + 1)->position();
    const auto& p2 = f.vertexMod((int) vi - 1)->position();
    return (p2 - p0).angle(p1 - p0);
}
 
} // namespace vcl
 
#endif // VCL_MESH_ELEM_ALGORITHMS_POLYGON_GEOMETRY_H