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0ad/source/simulation2/helpers/Los.h

129 lines
3.6 KiB
C++

/* Copyright (C) 2020 Wildfire Games.
* This file is part of 0 A.D.
*
* 0 A.D. is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 2 of the License, or
* (at your option) any later version.
*
* 0 A.D. is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with 0 A.D. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef INCLUDED_LOS
#define INCLUDED_LOS
// It doesn't seem worth moving the implementation to c++ and early-declaring Grid
// since files must include "Los.h" explicitly, and that's only done in .cpp files.
#include "Grid.h"
/**
* Computing LOS data at a very high resolution is not necessary and quite slow.
* This is the size, in meters, separating each LOS vertex.
* (Note that this also means it is the minimal meaningful resolution of any vision range change).
*/
static constexpr i32 LOS_TILE_SIZE = 4;
enum class LosState : u8
{
UNEXPLORED = 0,
EXPLORED = 1,
VISIBLE = 2,
MASK = 3
};
/**
* Object providing efficient abstracted access to the LOS state.
* This depends on some implementation details of CCmpRangeManager.
*
* This *ignores* the GetLosRevealAll flag - callers should check that explicitly.
*/
class CLosQuerier
{
private:
friend class CCmpRangeManager;
friend class TestLOSTexture;
CLosQuerier(u32 playerMask, const Grid<u32>& data, ssize_t verticesPerSide) :
m_Data(data), m_PlayerMask(playerMask), m_VerticesPerSide(verticesPerSide)
{
}
const CLosQuerier& operator=(const CLosQuerier&); // not implemented
public:
/**
* Returns whether the given vertex is visible (i.e. is within a unit's LOS).
*/
inline bool IsVisible(ssize_t i, ssize_t j) const
{
if (!(i >= 0 && j >= 0 && i < m_VerticesPerSide && j < m_VerticesPerSide))
return false;
// Check high bit of each bit-pair
if ((m_Data.get(i, j) & m_PlayerMask) & 0xAAAAAAAAu)
return true;
else
return false;
}
/**
* Returns whether the given vertex is explored (i.e. was (or still is) within a unit's LOS).
*/
inline bool IsExplored(ssize_t i, ssize_t j) const
{
if (!(i >= 0 && j >= 0 && i < m_VerticesPerSide && j < m_VerticesPerSide))
return false;
// Check low bit of each bit-pair
if ((m_Data.get(i, j) & m_PlayerMask) & 0x55555555u)
return true;
else
return false;
}
/**
* Returns whether the given vertex is visible (i.e. is within a unit's LOS).
* i and j must be in the range [0, verticesPerSide), else behaviour is undefined.
*/
inline bool IsVisible_UncheckedRange(ssize_t i, ssize_t j) const
{
#ifndef NDEBUG
ENSURE(i >= 0 && j >= 0 && i < m_VerticesPerSide && j < m_VerticesPerSide);
#endif
// Check high bit of each bit-pair
if ((m_Data.get(i, j) & m_PlayerMask) & 0xAAAAAAAAu)
return true;
else
return false;
}
/**
* Returns whether the given vertex is explored (i.e. was (or still is) within a unit's LOS).
* i and j must be in the range [0, verticesPerSide), else behaviour is undefined.
*/
inline bool IsExplored_UncheckedRange(ssize_t i, ssize_t j) const
{
#ifndef NDEBUG
ENSURE(i >= 0 && j >= 0 && i < m_VerticesPerSide && j < m_VerticesPerSide);
#endif
// Check low bit of each bit-pair
if ((m_Data.get(i, j) & m_PlayerMask) & 0x55555555u)
return true;
else
return false;
}
private:
u32 m_PlayerMask;
const Grid<u32>& m_Data;
ssize_t m_VerticesPerSide;
};
#endif // INCLUDED_LOS