axis_flip_mesh.hpp

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#ifndef GENERATOR_AXISFLIPMESH_HPP
#define GENERATOR_AXISFLIPMESH_HPP
 
#include "transform_mesh.hpp"
#include "triangle.hpp"
 
namespace generator
{
 
template<typename mesh_t>
class axis_flip_mesh_t
{
private:
    using impl_t = transform_mesh_t<mesh_t>;
    impl_t transform_mesh_;
 
public:
    class triangles_t
    {
    public:
        triangle_t generate() const
        {
            triangle_t triangle = triangles_.generate();
            if(mesh_->flip_)
                std::swap(triangle.vertices[0], triangle.vertices[2]);
            return triangle;
        }
 
        bool done() const noexcept
        {
            return triangles_.done();
        }
 
        void next()
        {
            triangles_.next();
        }
 
    private:
        const axis_flip_mesh_t* mesh_;
 
        typename triangle_generator_type<transform_mesh_t<mesh_t>>::type triangles_;
 
        explicit triangles_t(const axis_flip_mesh_t& mesh) : mesh_{&mesh}, triangles_{mesh.transform_mesh_.triangles()}
        {
        }
 
        friend class axis_flip_mesh_t;
    };
 
    axis_flip_mesh_t(mesh_t mesh, bool x, bool y, bool z)
        : transform_mesh_{std::move(mesh),
                          [x, y, z](mesh_vertex_t& vertex)
                          {
                              if(x)
                              {
                                  vertex.position[0] *= -1.0;
                                  vertex.normal[0] *= -1.0;
                              }
 
                              if(y)
                              {
                                  vertex.position[1] *= -1.0;
                                  vertex.normal[1] *= -1.0;
                              }
 
                              if(z)
                              {
                                  vertex.position[2] *= -1.0;
                                  vertex.normal[2] *= -1.0;
                              }
                          }}
        , flip_{false}
    {
        if(x)
            flip_ = !flip_;
        if(y)
            flip_ = !flip_;
        if(z)
            flip_ = !flip_;
    }
 
    triangles_t triangles() const noexcept
    {
        return triangles_t{*this};
    }
 
    using vertices_t = typename impl_t::vertices_t;
 
    vertices_t vertices() const noexcept
    {
        return transform_mesh_.vertices();
    }
 
private:
    bool flip_ = false;
};
 
template<typename mesh_t>
axis_flip_mesh_t<mesh_t> axis_flip_mesh(mesh_t mesh, bool x, bool y, bool z)
{
    return axis_flip_mesh_t<mesh_t>{std::move(mesh), x, y, z};
}
} // namespace generator
 
#endif