libcruft-util/region.cpp

/*
 * 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 2010-2017 Danny Robson <danny@nerdcruft.net>
 */


#include "region.hpp"

#include "debug/assert.hpp"

#include "coord/iostream.hpp"

#include <array>

using cruft::region;


//-----------------------------------------------------------------------------
template <size_t S, typename T>
cruft::region<S,T>::region (extent_t _extent):
    region (point_t::origin (), _extent)
{
    CHECK_SANITY (*this);
}


//-----------------------------------------------------------------------------
template <size_t S, typename T>
cruft::region<S,T>::region (point_t  _p,
                           extent_t _e):
    p (_p),
    e (_e)
{
    CHECK_SANITY (*this);
}


//-----------------------------------------------------------------------------
template <size_t S, typename T>
cruft::region<S,T>::region (point_t _a,
                           point_t _b):
    region (_a, extent_t { _b - _a })
{
    // This check must allow for zero area (but non-zero dimension) regions.
    // Some code paths need to support this degenerate case. It's ugly but
    // simplifies generalisation. eg, vertical linear bezier curves.
    CHECK (all (_a <= _b));

    CHECK_SANITY (*this);
}


//-----------------------------------------------------------------------------
template <size_t S, typename T>
typename cruft::region<S,T>::extent_t
cruft::region<S,T>::magnitude (void) const
{
    return e;
}


//-----------------------------------------------------------------------------
template <size_t S, typename T>
typename cruft::region<S,T>::extent_t
cruft::region<S,T>::magnitude (extent_t _e)
{
    e = _e;
    return e;
}


//-----------------------------------------------------------------------------
template <size_t S, typename T>
bool
cruft::region<S,T>::empty (void) const
{
    return almost_zero (area ());
}


//-----------------------------------------------------------------------------
template <size_t S, typename T>
typename cruft::region<S,T>::point_t
cruft::region<S,T>::base (void) const
{
    return p;
}


//-----------------------------------------------------------------------------
template <size_t S, typename T>
typename cruft::region<S,T>::point_t
cruft::region<S,T>::away (void) const
{
    return p + e;
}


//-----------------------------------------------------------------------------
template <size_t S, typename T>
typename cruft::region<S,T>::point_t
cruft::region<S,T>::centre (void) const
{
    return p + e / T{2};
}


//-----------------------------------------------------------------------------
template <size_t S, typename T>
typename cruft::region<S,T>::point_t
cruft::region<S,T>::closest (point_t q) const
{
    return clamp (q, p, p + e);
}


//-----------------------------------------------------------------------------
// FIXME: This will fail with an actual infinite range (NaNs will be generated
// in the conditionals).
template <size_t S, typename T>
bool
cruft::region<S,T>::intersects (region<S,T> rhs) const
{
    for (size_t i = 0; i < S; ++i)
        if (    p[i] >= rhs.p[i] + rhs.e[i] ||
            rhs.p[i] >=     p[i] +     e[i])
        { return false; }

    return true;
}


//-----------------------------------------------------------------------------
template <size_t S, typename T>
typename region<S,T>::point_t
region<S,T>::constrain (point_t q) const noexcept
{
    return closest (q);
}


//-----------------------------------------------------------------------------
template<size_t S, typename T>
cruft::region<S,T>
cruft::region<S,T>::intersection (region<S,T> rhs) const
{
    // find the intersection corners
    point_t a, b;

    for (size_t i = 0; i < S; ++i) {
        a[i] = cruft::max (p[i],        rhs.p[i]);
        b[i] = cruft::min (p[i] + e[i], rhs.p[i] + rhs.e[i]);

        if (b[i] < a[i])
            throw std::logic_error ("no overlap");
    }

    return { a, b };
}


//-----------------------------------------------------------------------------
template <size_t S, typename T>
bool
cruft::region<S,T>::covers (region<S, T> r) const noexcept
{
    return all (p <= r.p) && all (p + e >= r.p + r.e);
}


///////////////////////////////////////////////////////////////////////////////
template <size_t S, typename T>
cruft::region<S,T>
cruft::region<S,T>::inset (T mag) const
{
    return inset (cruft::vector<S,T> {mag});
}


//-----------------------------------------------------------------------------
template <size_t S, typename T>
cruft::region<S,T>
cruft::region<S,T>::inset (vector<S,T> mag) const
{
    // ensure we have enough space to trim off our total extent
    CHECK (all (e >= T{2} * mag));

    return {
        p +        mag,
        e - T{2} * mag
    };
}


//-----------------------------------------------------------------------------
template <size_t S, typename T>
cruft::region<S,T>
cruft::region<S,T>::expand (vector<S,T> v) const
{
    return {
        p - v,
        e + v * T{2}
    };
}


//-----------------------------------------------------------------------------
template <size_t S, typename T>
cruft::region<S,T>
cruft::region<S,T>::expand (T mag) const
{
    return expand (vector<S,T> {mag});
}


///////////////////////////////////////////////////////////////////////////////
template <size_t S, typename T>
cruft::region<S,T>
cruft::region<S,T>::operator+ (vector<S,T> rhs) const
{
    return { p + rhs, e };
}


//-----------------------------------------------------------------------------
template <size_t S, typename T>
cruft::region<S,T>
cruft::region<S,T>::operator- (vector<S,T> rhs) const
{
    return { p - rhs, e };
}


///////////////////////////////////////////////////////////////////////////////
template <size_t S, typename T>
bool
cruft::region<S,T>::operator== (region rhs) const
{
    return p == rhs.p && e == rhs.e;
}


///////////////////////////////////////////////////////////////////////////////
template <typename T>
cruft::region<2,T>
cruft::rotate90 (cruft::region<2,T> obj, int steps)
{
    CHECK_INCLUSIVE (steps, 0, 3);

    switch (steps) {
    case 0:
        return obj;

    case 1:
        return region2<T> {
            point2<T> {
                T(obj.p.x - obj.e.h),
                obj.p.y
            },
            extent2<T> {
                obj.e.h,
                obj.e.w,
            }
        };

    case 2:
        return region2<T> {
            point2<T> {
                obj.p.x,
                T(obj.p.y - obj.e.h),
            },
            obj.e,
        };

    case 3:
        return region2<T> {
            obj.p,
            extent2<T> {
                obj.e.h,
                obj.e.w,
            },
        };
    }

    unreachable();
}


//-----------------------------------------------------------------------------
template cruft::region2<i32> cruft::rotate90 (cruft::region2<i32>, int);
template cruft::region2<i64> cruft::rotate90 (cruft::region2<i64>, int);
template cruft::region2<f32> cruft::rotate90 (cruft::region2<f32>, int);



///////////////////////////////////////////////////////////////////////////////
template <size_t S, typename T>
std::ostream&
cruft::operator<< (std::ostream &os, const cruft::region<S,T> &rhs) {
    return os << "{ position: " << rhs.p << ", extent: " << rhs.e << " }";
}


///////////////////////////////////////////////////////////////////////////////
namespace cruft::debug {
    template <size_t S, typename T>
    struct validator<cruft::region<S,T>> {
        static bool is_valid (const cruft::region<S,T> &r)
        {
            return cruft::debug::is_valid (r.p) && cruft::debug::is_valid (r.e);
        }
    };
}


///////////////////////////////////////////////////////////////////////////////
#define INSTANTIATE_S_T(S,T)                                                    \
template struct cruft::region<S,T>;                                             \
template std::ostream& cruft::operator<< (std::ostream&, const region<S,T>&);   \
template struct cruft::debug::validator<cruft::region<S,T>>;

#define INSTANTIATE(T)  \
INSTANTIATE_S_T(2,T)    \
INSTANTIATE_S_T(3,T)

INSTANTIATE(i16);
INSTANTIATE(i32);
INSTANTIATE(i64);

INSTANTIATE(u16)
INSTANTIATE(u32)
INSTANTIATE(u64)

INSTANTIATE(f32)
INSTANTIATE(f64)