libcruft-util/region.hpp
Danny Robson a016e98b12 region: add make_range for regions
introduces an object that provides iterators suitable for row-major
scanning of points covering a region object. mostly a wrapper for the
equivalent extent_range.
2017-08-21 18:48:52 +10:00

222 lines
7.1 KiB
C++

/*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* Copyright 2010-2017 Danny Robson <danny@nerdcruft.net>
*/
#ifndef CRUFT_UTIL_REGION_HPP
#define CRUFT_UTIL_REGION_HPP
#include "./extent.hpp"
#include "./point.hpp"
#include "./vector.hpp"
#include "./types/traits.hpp"
#include <ostream>
namespace util {
/**
* A two-dimensional rectangle, with size and position.
*/
template <size_t S, typename T>
struct region {
using extent_t = util::extent<S,T>;
using point_t = util::point<S,T>;
using value_type = T;
//---------------------------------------------------------------------
static constexpr size_t dimension = S;
static constexpr size_t elements = extent_t::elements + point_t::elements;
point_t p;
extent_t e;
//---------------------------------------------------------------------
region () = default;
explicit region (extent_t);
region (point_t, extent_t);
region (point_t, point_t);
//---------------------------------------------------------------------
template <typename U>
constexpr region<S,U> cast (void) const;
//---------------------------------------------------------------------
T area (void) const;
T diameter (void) const;
extent_t magnitude (void) const;
extent_t magnitude (extent_t);
bool empty (void) const;
//---------------------------------------------------------------------
point_t base (void) const;
point_t away (void) const;
point_t centre (void) const;
point_t closest (point_t) const;
//---------------------------------------------------------------------
// exclusive of borders
bool intersects (region<S,T>) const;
// Compute binary region combinations
region intersection (region<S,T>) const;
// Test if a region lies completely within our space
bool covers (region<S,T>) const noexcept;
// Test if a point lies within out space. Inclusive of borders
bool covers (point<S,T>) const noexcept;
// Move a point to be within the region bounds
point_t constrain (point_t) const noexcept;
//---------------------------------------------------------------------
// Compute a region `mag` units into the region
region inset (T mag) const;
region inset (vector<S,T> mag) const;
region expand (T mag) const;
region expand (vector<S,T>) const;
// arithmetic operators
region operator+ (vector<S,T>) const;
region operator- (vector<S,T>) const;
// Logical comparison operators
bool operator ==(region<S,T> rhs) const;
bool operator !=(region<S,T> rhs) const
{ return !(*this == rhs); }
// Utility constants
static constexpr region<S,T> max (void);
static constexpr region<S,T> unit (void);
static constexpr region<S,T> zero (void)
{ return { point_t {0}, extent_t {0} }; }
void sanity (void) const;
};
///////////////////////////////////////////////////////////////////////////
/// constructs the minimal region that encompasses a region and a point.
template <typename T, size_t S>
region<S,T>
make_union (region<S,T> r, point<S,T> p)
{
const auto p0 = select (r.p < p, r.p, p);
const auto p1 = select (r.away () > p, r.away (), p);
return { p0, p1 };
}
///////////////////////////////////////////////////////////////////////////
/// construct a point iterator across a given region, generating each
/// valid point in row-major sequence.
///
/// this is only defined for integral types as it's not clear how to
/// handle floats; it's _super_ unlikely anyone actually wants to visit
/// every single floating point value for a region (and if so they can
/// damn well code that monstrosity themselves).
template <
typename T,
std::size_t S,
typename = std::enable_if_t<
std::is_integral_v<T>, void
>
>
auto
make_range (region<S,T> r)
{
using region_t = region<S,T>;
using point_t = typename region_t::point_t;
using vector_t = util::vector<S,T>;
// this range object is mostly a wrapper around the existing
// extent_range object with a constant offset. it's not going to be as
// performant, but when we discover this is an issue we can do write a
// better version of this object & iterator.
class region_range {
public:
class iterator : public std::iterator<std::forward_iterator_tag, point_t, size_t> {
public:
iterator (typename extent_range<S,T>::iterator _inner, vector_t _offset):
m_inner (_inner),
m_offset (_offset)
{ ; }
point_t operator* (void) const { return *m_inner + m_offset; }
iterator&
operator++ (void)
{
++m_inner;
return *this;
}
bool operator== (const iterator &rhs) const
{
assert (m_offset == rhs.m_offset);
return m_inner == rhs.m_inner;
}
bool operator!= (const iterator &rhs) const
{ return !(*this == rhs); }
private:
typename extent_range<S,T>::iterator m_inner;
vector_t m_offset;
};
region_range (region_t _r):
m_range { _r.e + T{1} },
m_offset { _r.p.template as<util::vector> () }
{ ; }
iterator begin (void) const { return { m_range.begin (), m_offset }; }
iterator end (void) const { return { m_range.end (), m_offset }; }
iterator cbegin (void) const { return begin (); }
iterator cend (void) const { return end (); }
private:
const extent_range<S,T> m_range;
const vector_t m_offset;
};
return region_range { r };
};
template <typename T> using region2 = region<2,T>;
template <typename T> using region3 = region<3,T>;
using region2u = region2<unsigned>;
using region2i = region2<int>;
using region2f = region2<float>;
using region2d = region2<double>;
template <size_t S, typename T>
std::ostream& operator<< (std::ostream&, const util::region<S,T>&);
}
#include "region.ipp"
#endif