387 lines
13 KiB
C++
387 lines
13 KiB
C++
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/* BSD 3-Clause License
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*
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* Copyright © 2008-2022, Jice and the libtcod contributors.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* 3. Neither the name of the copyright holder nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef _TCOD_BRESENHAM_HPP
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#define _TCOD_BRESENHAM_HPP
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#include <array>
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#include <functional>
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#include <iterator>
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#include <vector>
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#include "bresenham.h"
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// clang-format off
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class TCODLIB_API TCODLineListener {
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public :
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virtual bool putPoint(int x,int y) = 0;
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virtual ~TCODLineListener() {}
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};
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class TCODLIB_API TCODLine {
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public :
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/**
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@PageName line
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@PageCategory Base toolkits
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@PageTitle Line drawing toolkit
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@PageDesc This toolkit is a very simple and lightweight implementation of the bresenham line drawing algorithm. It allows you to follow straight paths on your map very easily.
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@FuncTitle Initializing the line
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@FuncDesc First, you have to initialize the toolkit with your starting and ending coordinates.
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@Cpp static void TCODLine::init (int xFrom, int yFrom, int xTo, int yTo)
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@C void TCOD_line_init (int xFrom, int yFrom, int xTo, int yTo)
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@Py line_init (xFrom, yFrom, xTo, yTo)
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@C# static void TCODLine::init(int xFrom, int yFrom, int xTo, int yTo)
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@Lua tcod.line.init(xFrom,yFrom, xTo,yTo)
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@Param xFrom,yFrom Coordinates of the line's starting point.
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@Param xTo,yTo Coordinates of the line's ending point.
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*/
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static void init(int xFrom, int yFrom, int xTo, int yTo);
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/**
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@PageName line
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@FuncTitle Walking the line
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@FuncDesc You can then step through each cell with this function. It returns true when you reach the line's ending point.
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@Cpp static bool TCODLine::step (int * xCur, int * yCur)
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@C bool TCOD_line_step (int * xCur, int * yCur)
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@Py line_step () # returns x,y or None,None if finished
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@C# static bool TCODLine::step(ref int xCur, ref int yCur)
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@Lua tcod.line.step(x,y) -- returns lineEnd,x,y
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@Param xCur,yCur the coordinates of the next cell on the line are stored here when the function returns
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@CppEx
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// Going from point 5,8 to point 13,4
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int x = 5, y = 8;
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TCODLine::init(x,y,13,4);
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do {
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// update cell x,y
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} while (!TCODLine::step(&x,&y));
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@CEx
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int x = 5, y = 8;
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TCOD_line_init(x,y,13,4);
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do {
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// update cell x,y
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} while (!TCOD_line_step(&x,&y));
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@PyEx
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libtcod.line_init(5,8,13,4)
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# update cell 5,8
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x,y=libtcod.line_step()
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while (not x is None) :
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# update cell x,y
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x,y=libtcod.line_step()
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@LuaEx
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x=5
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y=8
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tcod.line.init(x,y,13,4)
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repeat
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-- update cell x,y
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lineEnd,x,y = tcod.line.step(x,y)
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until lineEnd
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*/
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static bool step(int *xCur, int *yCur);
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/**
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@PageName line
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@FuncTitle Callback-based function
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@FuncDesc The function returns false if the line has been interrupted by the callback (it returned false before the last point).
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@Cpp
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class TCODLIB_API TCODLineListener {
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virtual bool putPoint (int x, int y) = 0;
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};
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static bool TCODLine::line (int xFrom, int yFrom, int xTo, int yTo, TCODLineListener * listener)
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@C
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typedef bool (*TCOD_line_listener_t) (int x, int y);
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bool TCOD_line(int xFrom, int yFrom, int xTo, int yTo, TCOD_line_listener_t listener)
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@Py
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def line_listener(x,y) : # ...
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line(xFrom, yFrom, xTo, yTo, listener)
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@C# static bool line(int xFrom, int yFrom, int xTo, int yTo, TCODLineListener listener)
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@Param xFrom,yFrom Coordinates of the line's starting point.
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@Param xTo,yTo Coordinates of the line's ending point.
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@Param listener Callback called for each line's point. The function stops if the callback returns false.
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@CppEx // Going from point 5,8 to point 13,4
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class MyLineListener : public TCODLineListener {
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public:
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bool putPoint (int x,int y) {
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printf ("%d %d\n",x,y);
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return true;
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}
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};
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MyLineListener myListener;
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TCODLine::line(5,8,13,4,&myListener);
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@CEx bool my_listener(int x,int y) {
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printf ("%d %d\n",x,y);
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return true;
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}
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TCOD_line_line(5,8,13,4,my_listener);
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@PyEx def my_listener(x,y):
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print x,y
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return True
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libtcod.line_line(5,8,13,4,my_listener)
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*/
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static bool line(int xFrom, int yFrom, int xTo, int yTo, TCODLineListener *listener);
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};
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// clang-format on
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namespace tcod {
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/**
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Encapsulates a Bresenham line drawing algorithm.
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\rst
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.. versionadded:: 1.17
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\endrst
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*/
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class BresenhamLine {
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public:
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using Point2 = std::array<int, 2>;
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using iterator_category = std::random_access_iterator_tag;
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using value_type = Point2;
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using difference_type = int;
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using pointer = void;
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using reference = value_type;
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/**
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Construct a new Bresenham line from `begin` to `end`.
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Iterating over this instance will include both endpoints.
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*/
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explicit BresenhamLine(Point2 begin, Point2 end) noexcept
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: origin_{begin},
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dest_{end},
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index_{0},
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index_end_{get_delta_x() + 1},
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cursor_{0, 0},
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y_error_{-get_delta_x() / 2} {}
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/**
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Construct a new Bresenham line with a manually given error value.
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*/
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explicit BresenhamLine(Point2 begin, Point2 end, int error) noexcept
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: origin_{begin},
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dest_{end},
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index_{0},
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index_end_{get_delta_x() + 1},
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cursor_{0, 0},
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y_error_{error > 0 ? error % get_delta_x() - get_delta_x() : error % get_delta_x()} {}
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inline BresenhamLine& operator++() noexcept {
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++index_;
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return *this;
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}
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inline BresenhamLine operator++(int) noexcept {
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auto tmp = *this;
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++(*this);
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return tmp;
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}
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inline BresenhamLine& operator--() noexcept {
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--index_;
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return *this;
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}
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inline BresenhamLine operator--(int) noexcept {
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auto tmp = *this;
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--(*this);
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return tmp;
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}
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/**
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Return the world position of the Bresenham at the index relative to the current index.
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BresenhamLine is not restricted by any bounds so you can freely give a index past the end or before zero.
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The internal state must always seek to the position being indexed, this will affect performance depending on if
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successive indexes are close together or far apart.
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*/
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inline value_type operator[](int index) noexcept { return bresenham_get(index_ + index); }
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/**
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Return the world position of the Bresenham at the current index.
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*/
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inline value_type operator*() noexcept { return (*this)[0]; }
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inline constexpr bool operator==(const BresenhamLine& rhs) const noexcept { return index_ == rhs.index_; }
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inline constexpr bool operator!=(const BresenhamLine& rhs) const noexcept { return !(*this == rhs); }
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inline constexpr difference_type operator-(const BresenhamLine& rhs) const noexcept { return index_ - rhs.index_; }
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/**
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Return a new version of this BresenhamLine with an adjusted range.
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`shift_begin` and `shift_end` change the beginning and ending of the line
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when iterators over.
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Example::
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// Remove the endpoints of a bresenham line.
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auto line = tcod::BresenhamLine(from, to).adjust_range(1, -1);
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*/
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inline BresenhamLine adjust_range(int shift_begin, int shift_end) const noexcept {
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BresenhamLine new_data{*this};
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new_data.index_ += shift_begin;
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new_data.index_end_ += shift_end;
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new_data.index_end_ = std::max(new_data.index_, new_data.index_end_);
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return new_data;
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}
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/**
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Remove the staring endpoint of a line.
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Example::
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for (auto&& [x, y] : tcod::BresenhamLine(from, to).without_start()) {
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// All positions excluding `from`.
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}
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*/
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inline BresenhamLine without_start() const noexcept { return adjust_range(1, 0); }
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/**
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Remove the final endpoint of a line.
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Example::
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for (auto&& [x, y] : tcod::BresenhamLine(from, to).without_end()) {
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// All positions excluding `to`.
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}
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*/
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inline BresenhamLine without_end() const noexcept { return adjust_range(0, -1); }
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/**
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Remove both endpoints of a line.
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Example::
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for (auto&& [x, y] : tcod::BresenhamLine(from, to).without_endpoints()) {
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// All positions between and excluding `from` and `to`.
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}
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*/
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inline BresenhamLine without_endpoints() const noexcept { return adjust_range(1, -1); }
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/**
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Return the beginning iterator, which is a copy of the current object.
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*/
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inline BresenhamLine begin() const noexcept { return {*this}; }
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/**
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Return the past-the-end iterator.
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*/
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inline BresenhamLine end() const noexcept {
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return BresenhamLine{origin_, dest_, index_end_, index_end_, cursor_, y_error_};
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}
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private:
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/**
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Transform matrix to convert from normalized state cursor to the real world coordinates.
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*/
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struct Matrix {
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/**
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Convert a state cursor vector to the a world vector.
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*/
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inline Point2 transform(const Point2& cursor) const noexcept {
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return {ax + cursor.at(0) * xx + cursor.at(1) * yx, ay + cursor.at(0) * xy + cursor.at(1) * yy};
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}
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int ax; // Affine transformation on X.
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int ay; // Affine transformation on Y.
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int_fast8_t xx; // Index to world X.
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int_fast8_t xy; // Index to world Y.
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int_fast8_t yx; // Cursor Y to world X.
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int_fast8_t yy; // Cursor Y to world Y.
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};
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/**
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Return a Matrix that converts a normalized cursor to the correct octant.
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*/
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inline Matrix get_matrix() const noexcept { return get_matrix(origin_, dest_); }
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static Matrix get_matrix(const Point2& origin, const Point2& dest) noexcept {
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const int delta_x = dest.at(0) - origin.at(0);
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const int delta_y = dest.at(1) - origin.at(1);
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Matrix matrix{
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origin.at(0),
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origin.at(1),
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1,
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0,
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0,
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1,
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};
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if (delta_x < 0) matrix.xx = -1;
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if (delta_y < 0) matrix.yy = -1;
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if (std::abs(delta_y) > std::abs(delta_x)) {
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std::swap(matrix.xx, matrix.yx);
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std::swap(matrix.xy, matrix.yy);
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}
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return matrix;
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}
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explicit BresenhamLine(Point2 begin, Point2 end, int index_begin, int index_end, Point2 cursor, int error) noexcept
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: origin_{begin}, dest_{end}, index_{index_begin}, index_end_{index_end}, cursor_{cursor}, y_error_{error} {}
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/**
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Return the normalized delta vector.
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The first axis is always the longest. All values are non-negative.
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*/
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inline Point2 get_normalized_delta() const noexcept { return get_normalized_delta(origin_, dest_); }
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static Point2 get_normalized_delta(const Point2& origin, const Point2& dest) noexcept {
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return std::abs(dest.at(0) - origin.at(0)) > std::abs(dest.at(1) - origin.at(1))
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? Point2{std::abs(dest.at(0) - origin.at(0)), std::abs(dest.at(1) - origin.at(1))}
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: Point2{std::abs(dest.at(1) - origin.at(1)), std::abs(dest.at(0) - origin.at(0))};
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}
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/**
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Return the normalized delta X value.
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This is the value of the longest delta axis as a positive integer and is often used to determine the line length.
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*/
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inline int get_delta_x() const noexcept { return get_normalized_delta().at(0); }
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/**
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Advance one step using the Bresenham algorithm.
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*/
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inline BresenhamLine& bresenham_next() {
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||
|
|
const Point2 delta = get_normalized_delta();
|
||
|
|
y_error_ += delta.at(1);
|
||
|
|
if (y_error_ > 0) {
|
||
|
|
++cursor_.at(1);
|
||
|
|
y_error_ -= delta.at(0);
|
||
|
|
};
|
||
|
|
++cursor_.at(0);
|
||
|
|
return *this;
|
||
|
|
}
|
||
|
|
/**
|
||
|
|
Inverse Bresenham algorithm. Takes one step backwards.
|
||
|
|
*/
|
||
|
|
inline BresenhamLine& bresenham_prev() {
|
||
|
|
const Point2 delta = get_normalized_delta();
|
||
|
|
y_error_ -= delta.at(1);
|
||
|
|
if (y_error_ <= -delta.at(0)) {
|
||
|
|
--cursor_.at(1);
|
||
|
|
y_error_ += delta.at(0);
|
||
|
|
};
|
||
|
|
--cursor_.at(0);
|
||
|
|
return *this;
|
||
|
|
}
|
||
|
|
/**
|
||
|
|
Seek to the given index and return the world position of the cursor.
|
||
|
|
*/
|
||
|
|
inline Point2 bresenham_get(int index) {
|
||
|
|
while (cursor_.at(0) < index) bresenham_next();
|
||
|
|
while (cursor_.at(0) > index) bresenham_prev();
|
||
|
|
return get_matrix().transform(cursor_);
|
||
|
|
}
|
||
|
|
Point2 origin_; // Starting point.
|
||
|
|
Point2 dest_; // Ending point.
|
||
|
|
int index_; // The starting index returned by `begin`.
|
||
|
|
int index_end_; // The past-the-end index returned by `end`.
|
||
|
|
Point2 cursor_; // Normalized Bresenham low-slope position. First axis acts as the current index.
|
||
|
|
int y_error_; // Fractional difference between Y indexes. Is always `-delta[0] < err <= 0`.
|
||
|
|
};
|
||
|
|
} // namespace tcod
|
||
|
|
#endif
|