cgal/Isosurfacing_3/include/CGAL/Cartesian_grid_3.h

299 lines
7.1 KiB
C++

// Copyright (c) 2022 INRIA Sophia-Antipolis (France).
// All rights reserved.
//
// This file is part of CGAL (www.cgal.org).
//
// $URL$
// $Id$
// SPDX-License-Identifier: GPL-3.0-or-later OR LicenseRef-Commercial
//
// Author(s) : Julian Stahl
#ifndef CGAL_CARTESIAN_GRID_3_H
#define CGAL_CARTESIAN_GRID_3_H
#include <CGAL/license/Isosurfacing_3.h>
#include <CGAL/Bbox_3.h>
#include <CGAL/Image_3.h>
#include <CGAL/Isosurfacing_3/internal/Grid_topology.h>
#include <array>
#include <type_traits>
#include <vector>
namespace CGAL {
/**
* \ingroup PkgIsosurfacing3Ref
*
* \brief Stores scalar values and gradients at points of a cartesian grid.
*
* \tparam GeomTraits the traits type
*/
template <typename GeomTraits>
class Cartesian_grid_3
{
public:
using Geom_traits = GeomTraits;
using FT = typename Geom_traits::FT;
using Vector = typename Geom_traits::Vector_3;
using VertexDescriptor = Isosurfacing::internal::Grid_topology::Vertex_descriptor;
public:
/**
* \ingroup PkgIsosurfacing3Ref
*
* \brief Create a grid with `xdim * ydim * zdim` grid points.
* The grid covers the space described by a bounding box.
*
* \param xdim the number of grid points in x direction
* \param ydim the number of grid points in y direction
* \param zdim the number of grid points in z direction
* \param bbox the bounding box
*/
Cartesian_grid_3(const std::size_t xdim,
const std::size_t ydim,
const std::size_t zdim,
const Bbox_3& bbox)
: sizes{xdim, ydim, zdim},
bbox(bbox)
{
// pre-allocate memory
values.resize(xdim * ydim * zdim);
gradients.resize(xdim * ydim * zdim);
// calculate grid spacing
const FT d_x = bbox.x_span() / (xdim - 1);
const FT d_y = bbox.y_span() / (ydim - 1);
const FT d_z = bbox.z_span() / (zdim - 1);
spacing = Vector(d_x, d_y, d_z);
}
/**
* \ingroup PkgIsosurfacing3Ref
*
* \brief Create a grid from an `Image_3`.
* The dimensions and bounding box are read from the image.
* The values stored in the image must be of type `Geom_traits::FT` or implicitly convertible to it.
*
* \param image the image providing the data
*/
Cartesian_grid_3(const Image_3& image)
{
from_image(image);
}
/**
* \ingroup PkgIsosurfacing3Ref
*
* \brief Get the value stored in the grid at the grid point described by the vertex.
*
* \param v the vertex descriptor of the vertex
*
* \return the stored value
*/
FT operator()(const VertexDescriptor& v) const
{
return values[linear_index(v[0], v[1], v[2])];
}
/**
* \ingroup PkgIsosurfacing3Ref
*
* \brief Get the value stored in the grid at the given indices.
*
* \param x the index in x direction
* \param y the index in y direction
* \param z the index in z direction
*
* \return the stored value
*/
FT value(const std::size_t x,
const std::size_t y,
const std::size_t z) const
{
return values[linear_index(x, y, z)];
}
/**
* \ingroup PkgIsosurfacing3Ref
*
* \brief Get a reference to the value stored in the grid at the given indices.
* Can be used to set values of the grid.
*
* \param x the index in x direction
* \param y the index in y direction
* \param z the index in z direction
*
* \return a reference to the stored value
*/
FT& value(const std::size_t x,
const std::size_t y,
const std::size_t z)
{
return values[linear_index(x, y, z)];
}
Vector gradient(const std::size_t x,
const std::size_t y,
const std::size_t z) const
{
return gradients[linear_index(x, y, z)];
}
Vector& gradient(const std::size_t x,
const std::size_t y,
const std::size_t z)
{
return gradients[linear_index(x, y, z)];
}
/**
* \ingroup PkgIsosurfacing3Ref
*
* \return the number of grid points in x direction
*/
std::size_t xdim() const
{
return sizes[0];
}
/**
* \ingroup PkgIsosurfacing3Ref
*
* \return the number of grid points in y direction
*/
std::size_t ydim() const
{
return sizes[1];
}
/**
* \ingroup PkgIsosurfacing3Ref
*
* \return the number of grid points in z direction
*/
std::size_t zdim() const
{
return sizes[2];
}
const Bbox_3& get_bbox() const
{
return bbox;
}
const Vector& get_spacing() const
{
return spacing;
}
private:
std::size_t linear_index(const std::size_t x,
const std::size_t y,
const std::size_t z) const
{
// convert x, y, z into a linear index to access the vector
return (z * ydim() + y) * xdim() + x;
}
void from_image(const Image_3& image);
Image_3 to_image() const;
private:
std::vector<FT> values;
std::vector<Vector> gradients;
std::array<std::size_t, 3> sizes;
Bbox_3 bbox;
Vector spacing;
};
template <typename GeomTraits>
void
Cartesian_grid_3<GeomTraits>::
from_image(const Image_3& image)
{
// compute bounding box
const FT max_x = image.tx() + (image.xdim() - 1) * image.vx();
const FT max_y = image.ty() + (image.ydim() - 1) * image.vy();
const FT max_z = image.tz() + (image.zdim() - 1) * image.vz();
bbox = Bbox_3(image.tx(), image.ty(), image.tz(), max_x, max_y, max_z);
// get spacing
spacing = Vector(image.vx(), image.vy(), image.vz());
// get sizes
sizes[0] = image.xdim();
sizes[1] = image.ydim();
sizes[2] = image.zdim();
// pre-allocate
values.resize(xdim() * ydim() * zdim());
gradients.resize(xdim() * ydim() * zdim());
// copy values
for(std::size_t x=0; x<sizes[0]; ++x)
for(std::size_t y=0; y<sizes[1]; ++y)
for(std::size_t z=0; z<sizes[2]; ++z)
value(x, y, z) = image.value(x, y, z);
}
template <typename GeomTraits>
Image_3
Cartesian_grid_3<GeomTraits>::
to_image() const
{
// select the number type
WORD_KIND wordkind;
if(std::is_floating_point<FT>::value)
wordkind = WK_FLOAT;
else
wordkind = WK_FIXED;
// select signed or unsigned
SIGN sign;
if(std::is_signed<FT>::value)
sign = SGN_SIGNED;
else
sign = SGN_UNSIGNED;
// get spacing
const double vx = spacing()[0];
const double vy = spacing()[1];
const double vz = spacing()[2];
// create image
_image* im = _createImage(xdim(), ydim(), zdim(),
1, // vectorial dimension
vx, vy, vz, // voxel size
sizeof(FT), // image word size in bytes
wordkind, // image word kind WK_FIXED, WK_FLOAT, WK_UNKNOWN
sign); // image word sign
// error handling
if(im == nullptr || im->data == nullptr)
throw std::bad_alloc(); // @todo idk?
// set min coordinates
im->tx = bbox.xmin();
im->ty = bbox.ymin();
im->tz = bbox.zmin();
// copy data
FT* data = (FT*)im->data;
for(std::size_t x=0; x<xdim(); ++x)
for(std::size_t y=0; y<ydim(); ++y)
for(std::size_t z=0; z<zdim(); ++z)
data[(z * ydim() + y) * xdim() + x] = value(x, y, z);
return Image_3(im, Image_3::OWN_THE_DATA);
}
} // namespace CGAL
#endif // CGAL_CARTESIAN_GRID_3_H