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/*
This file is part of Minitrem.
Minitrem 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.
Minitrem 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 Minitrem. If not, see <http://www.gnu.org/licenses/>.
*/
#include "common.hpp"
namespace world {
static const v2f_t path_margin(5, 5);
// The path finder will try to walk in the eight directions listed below.
static const tile_index_t path_offsets[8] = {
{+1, 0}, {+1, +1}, {0, +1}, {-1, +1},
{-1, 0}, {-1, -1}, {0, -1}, {+1, -1}
};
path_finder_t::~path_finder_t()
{
delete[] nodes;
}
void path_finder_t::setup_nodes(v2f_t src_, v2f_t dst_, cflags_t cflags_)
{
rectf_t src_margin, dst_margin;
tile_index_t end;
src = src_;
dst = dst_;
cflags = cflags_;
tile_center = v2f_t(0.5, 0.5);
shortest_dist = INFINITY;
src_margin[0] = src - path_margin;
src_margin[1] = src + path_margin;
dst_margin[0] = dst - path_margin;
dst_margin[1] = dst + path_margin;
bounds = src_margin | dst_margin;
base = tile_index_at(bounds[0]);
end = tile_index_at(bounds[1]);
width = end[0] - base[0] + 1;
height = end[1] - base[1] + 1;
nodes = new path_node_t[width * height];
for (size_t i = 0; i < width * height; i++) {
nodes[i].accessible = true;
nodes[i].dist = INFINITY;
}
}
void path_finder_t::eliminate_nodes(rectf_t bounds)
{
rect_t<coord_t, 2> index_bounds;
tile_index_t index;
bounds[0] -= tile_center;
bounds[1] -= tile_center;
index_bounds[0] = tile_index_t(bounds[0].ceil()) - base;
index_bounds[1] = tile_index_t(bounds[1].floor()) - base;
if (index_bounds[0][0] < 0)
index_bounds[0][0] = 0;
if (index_bounds[0][1] < 0)
index_bounds[0][1] = 0;
if (index_bounds[1][0] >= (coord_t)width)
index_bounds[1][0] = width - 1;
if (index_bounds[1][1] >= (coord_t)height)
index_bounds[1][1] = height - 1;
for (index[1] = index_bounds[0][1]; index[1] <= index_bounds[1][1]; index[1]++)
for (index[0] = index_bounds[0][0]; index[0] <= index_bounds[1][0]; index[0]++) {
path_node_t *node;
node = nodes + index[1] * width + index[0];
node->accessible = false;
}
}
path_node_t *path_finder_t::node_at(tile_index_t index)
{
return nodes + index[1] * width + index[0];
}
bool path_finder_t::is_accessible(tile_index_t index)
{
if (index[0] < 0 || index[1] < 0 ||
index[0] >= (coord_t)width || index[1] >= (coord_t)height)
return false;
return node_at(index)->accessible;
}
// Walking diagonally requires an additional accessibility test. The tables
// below list when it's needed and which tile is to be tested. For example,
// when walking north-west, the north and the west neighbors have to be tested
// for accessibility.
bool path_finder_t::diagonal_test(tile_index_t index, size_t i)
{
static const bool do_test[8] = {
false, true, false, true, false, true, false, true
};
static const tile_index_t offsets[8][2] = {
{},
{{+1, 0}, {0, +1}},
{},
{{0, +1}, {-1, 0}},
{},
{{-1, 0}, {0, -1}},
{},
{{0, -1}, {+1, 0}}
};
if (!do_test[i])
return true;
for (size_t j = 0; j < 2; j++)
if (!is_accessible(index + offsets[i][j]))
return false;
return true;
}
static const int visit_orders[4][8] = {
{0, 7, 1, 2, 6, 5, 3, 4}, // prefer +x
{2, 3, 1, 0, 4, 7, 5, 6}, // prefer +y
{4, 5, 3, 2, 6, 1, 7, 0}, // prefer -x
{6, 5, 7, 0, 4, 3, 1, 2} // prefer -y
};
static const int *visit_order(v2f_t delta)
{
if (delta[1] > delta[0]) {
if (delta[1] > -delta[0])
return visit_orders[1];
else
return visit_orders[2];
} else {
if (delta[1] > -delta[0])
return visit_orders[0];
else
return visit_orders[3];
}
return visit_orders[0];
}
void path_finder_t::find_r(tile_index_t index, float dist, float limit)
{
path_node_t *node;
v2f_t delta;
float dist_to_dst;
const int *order;
node = nodes + index[1] * width + index[0];
if (!node->accessible)
return;
if (node->dist <= dist)
return;
node->dist = dist;
path.push_back(index);
delta = dst - v2f_t(base + index) - tile_center;
dist_to_dst = delta.len();
if (dist_to_dst < 1.0f && dist + dist_to_dst < shortest_dist) {
shortest_path = path;
shortest_dist = dist + dist_to_dst;
return;
}
order = visit_order(delta);
for (size_t i = 0; i < 8; i++) {
tile_index_t offset, next;
offset = path_offsets[order[i]];
next = index + offset;
if (!is_accessible(next))
continue;
if (!diagonal_test(index, order[i]))
continue;
if (dist + v2f_t(offset).len() > limit)
continue;
find_r(next, dist + v2f_t(offset).len(), limit);
if (shortest_path.size())
return;
}
path.pop_back();
}
bool path_finder_t::find(void)
{
tile_index_t start;
start = tile_index_at(src) - base;
find_r(start, 0.0f, 100.0f);
return shortest_path.size() > 0;
}
void path_finder_t::export_path(std::list<v2f_t> *list)
{
list->clear();
for (tile_index_t &index : shortest_path)
list->push_back(v2f_t(index + base) + tile_center);
list->push_back(dst);
}
} // namespace world
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