libcruft-util/geom/aabb.hpp

207 lines
5.9 KiB
C++

/*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*
* Copyright 2015-2018 Danny Robson <danny@nerdcruft.net>
*/
#pragma once
#include "../debug/assert.hpp"
#include "../extent.hpp"
#include "../point.hpp"
#include <cstdint>
namespace cruft::geom {
///////////////////////////////////////////////////////////////////////////
/// represents an axis-aligned bounding-box through two opposing corners.
///
/// `lo' must be less-than-or-equal to `hi'. equality is allowed so that
/// we can represent zero sized bounding-boxes.
template <size_t S, typename T>
struct aabb {
aabb () = default;
aabb (point<S,T> _lo, point<S,T> _hi):
lo (_lo),
hi (_hi)
{
CHECK (all (lo <= hi));
}
///////////////////////////////////////////////////////////////////////
extent<S,T>
magnitude (void) const
{
return (hi - lo).template as<cruft::extent> ();
}
///--------------------------------------------------------------------
T
diameter (void) const
{
return magnitude ().diameter ();
}
///--------------------------------------------------------------------
/// tests whether a point lies within the region, inclusive of borders
constexpr bool
inclusive (point<S,T> p) const noexcept
{ return all (lo <= p && hi >= p); }
///--------------------------------------------------------------------
/// Find's the closest point on the AABB border to the supplied point.
point<S,T>
closest (point<S,T> query) const
{
return clamp (query, lo, hi);
}
///--------------------------------------------------------------------
/// Modifies the AABB to cover the supplied point inclusively.
void cover (point<S,T> p)
{
lo = min (p, lo);
hi = max (p, hi);
}
///////////////////////////////////////////////////////////////////////
/// Applies a negative offset to lo, and a positive offset to hi, and
/// returns the result.
///
/// The offset applied is identical for lo and hi, so one may need to
/// consider halving the supplied magnitude depending on the use case.
aabb<S,T>
expand [[nodiscard]] (T mag) const
{
return {
lo - mag,
hi + mag
};
}
///////////////////////////////////////////////////////////////////////
/// Adds a constant vector to both the lo and hi points.
aabb<S,T> operator+ (vector<S,T> v) const
{
return { lo + v, hi + v };
}
///--------------------------------------------------------------------
/// Substracts a constant vector from both the lo and hi points.
aabb<S,T> operator- (vector<S,T> v) const
{
return { lo - v, hi - v };
}
///////////////////////////////////////////////////////////////////////
/// Returns an aabb that covers the supplied point in addition to the
/// current aabb area.
auto operator| [[nodiscard]] (point<S,T> p) const noexcept
{
return aabb (
cruft::min (lo, p),
cruft::max (hi, p)
);
}
///--------------------------------------------------------------------
/// Modifies the AABB to cover the supplied point inclusively.
auto& operator|= (point<S,T> p) noexcept
{
return *this = *this | p;
}
///--------------------------------------------------------------------
/// Returns an AABB that covers this AABB and the supplied AABB.
aabb operator| [[nodiscard]] (aabb<S,T> rhs) const noexcept
{
return {
min (lo, rhs.lo),
max (hi, rhs.hi)
};
}
///--------------------------------------------------------------------
/// Returns a read only list of vertices for the AABB.
std::array<cruft::point<S,T>,cruft::pow(2,S)>
vertices (void) const noexcept;
///////////////////////////////////////////////////////////////////////
/// The most negative corner of the AABB.
::cruft::point<S,T> lo;
/// The most positive corner of the AABB.
::cruft::point<S,T> hi;
};
///////////////////////////////////////////////////////////////////////////
template <std::size_t S, typename T>
constexpr bool
operator== (const aabb<S,T> &a, const aabb<S,T> &b) noexcept
{
return a.lo == b.lo && a.hi == b.hi;
}
///////////////////////////////////////////////////////////////////////////
typedef aabb<2,float> aabb2f;
typedef aabb<2,unsigned> aabb2u;
typedef aabb<2,int> aabb2i;
typedef aabb<3,float> aabb3f;
typedef aabb<3,unsigned> aabb3u;
typedef aabb<3,int> aabb3i;
}
///////////////////////////////////////////////////////////////////////////////
#include "sample/fwd.hpp"
#include <random>
namespace cruft::geom::sample {
template <size_t S, typename T>
class volume<aabb<S,T>> {
public:
using shape_type = aabb<S,T>;
volume (shape_type&&);
volume (shape_type const &target):
m_target (target)
{ ; }
template <typename GeneratorT>
auto
eval (GeneratorT &&g) const noexcept
{
point<S,T> res;
for (size_t i = 0; i < S; ++i)
res[i] = cruft::random::uniform (m_target.lo[i], m_target.hi[i], g);
return res;
}
private:
shape_type const &m_target;
};
}