void run(const P& p0,
const bool* blocked,
int* out,
const P& map_dims,
int travel_lmt,
const P& p1,
const bool allow_diagonal)
{
std::fill_n(out, map_dims.x * map_dims.y, 0);
// List of positions to travel to
std::vector<P> positions;
// In the worst case we need to visit every position, reserve the elements
positions.reserve(map_dims.x * map_dims.y);
// Instead of removing evaluated positions from the vector, we track which
// index to try next (cheaper than erasing front elements).
size_t next_p_idx = 0;
int val = 0;
bool path_exists = true;
bool is_at_tgt = false;
bool is_stopping_at_tgt = p1.x != -1;
const R bounds(P(1, 1), map_dims - 2);
P p(p0);
const auto& dirs = allow_diagonal ?
dir_utils::dir_list :
dir_utils::cardinal_list;
bool done = false;
while (!done)
{
// "Flood" around the current position, and add those to the list of
// positions to travel to.
for (const P& d : dirs)
{
const P new_p(p + d);
if (
!blocked[idx2(new_p, map_dims.y)] &&
bounds.is_p_inside(new_p) &&
out[idx2(new_p, map_dims.y)] == 0 &&
new_p != p0)
{
val = out[idx2(p, map_dims.y)];
if (travel_lmt == -1 || val < travel_lmt)
{
out[idx2(new_p, map_dims.y)] = val + 1;
}
if (is_stopping_at_tgt && new_p == p1)
{
is_at_tgt = true;
break;
}
if (!is_stopping_at_tgt || !is_at_tgt)
{
positions.push_back(new_p);
}
}
} // Offset loop
if (is_stopping_at_tgt)
{
if (positions.size() == next_p_idx)
{
path_exists = false;
}
if (is_at_tgt || !path_exists)
{
done = true;
}
}
else if (positions.size() == next_p_idx)
{
done = true;
}
if (val == travel_lmt)
{
done = true;
}
if (!is_stopping_at_tgt || !is_at_tgt)
{
if (positions.size() == next_p_idx)
{
// No more positions to evaluate
path_exists = false;
}
else // There are more positions to evaluate
{
p = positions[next_p_idx];
++next_p_idx;
}
}
} // while
}
void run(const P& p0,
const P& p1,
const bool* blocked,
int* flood_buffer,
const P& map_dims,
std::vector<P>& out,
const bool allow_diagonal,
const bool randomize_steps)
{
out.clear();
if (p0 == p1)
{
// Origin and target is same cell
return;
}
floodfill::run(p0,
blocked,
flood_buffer,
map_dims,
-1,
p1,
allow_diagonal);
if (flood_buffer[idx2(p1, map_dims.y)] == 0)
{
// No path exists
return;
}
const std::vector<P>& dirs = allow_diagonal ?
dir_utils::dir_list :
dir_utils::cardinal_list;
const size_t nr_dirs = dirs.size();
// Corresponds to the elements in "dirs"
std::vector<bool> valid_offsets(nr_dirs, false);
// The path length will be equal to the flood value at the target cell, so
// we can reserve that many elements beforehand.
out.reserve(flood_buffer[idx2(p1, map_dims.y)]);
P p(p1);
out.push_back(p);
const R map_r(P(0, 0), map_dims - 1);
while (true)
{
const int val = flood_buffer[idx2(p, map_dims.y)];
P adj_p;
// Find valid offsets, and check if origin is reached
for (size_t i = 0; i < nr_dirs; ++i)
{
const P& d(dirs[i]);
adj_p = p + d;
if (adj_p == p0)
{
// Origin reached
return;
}
// TODO: What is the purpose of this check? If the current value is
// zero, doesn't that mean this cell is the target? Only the target
// cell and unreachable cells should have values of zero(?)
// Try removing the check and verify if the algorithm still works
if (val != 0)
{
const bool is_inside_map = map_r.is_p_inside(adj_p);
const int adj_val = is_inside_map ?
flood_buffer[idx2(adj_p, map_dims.y)] : 0;
// Mark this as a valid travel direction if it's fewer steps
// from the target than the current cell
valid_offsets[i] = adj_val < val;
}
}
// Set the next position to one of the valid offsets - either pick one
// randomly, or iterate over the list and pick the first valid choice.
if (randomize_steps)
{
std::vector<P> adj_p_bucket;
for (size_t i = 0; i < nr_dirs; ++i)
{
if (valid_offsets[i])
{
adj_p_bucket.push_back(p + dirs[i]);
}
}
ASSERT(!adj_p_bucket.empty());
adj_p = rnd::element(adj_p_bucket);
}
else // Do not randomize step choices - iterate over offset list
{
for (size_t i = 0; i < nr_dirs; ++i)
{
if (valid_offsets[i])
{
adj_p = P(p + dirs[i]);
break;
}
}
}
out.push_back(adj_p);
p = adj_p;
} //while
}
void run(const P& p0,
const P& p1,
const bool blocked[map_w][map_h],
std::vector<P>& out,
const bool allow_diagonal,
const bool randomize_steps)
{
out.clear();
if (p0 == p1)
{
// Origin and target is same cell
return;
}
int flood_buffer[map_w][map_h];
floodfill::run(p0,
blocked,
flood_buffer,
-1,
p1,
allow_diagonal);
if (flood_buffer[p1.x][p1.y] == 0)
{
// No path exists
return;
}
const std::vector<P>& dirs = allow_diagonal ?
dir_utils::dir_list :
dir_utils::cardinal_list;
const size_t nr_dirs = dirs.size();
// Corresponds to the elements in "dirs"
std::vector<bool> valid_offsets(nr_dirs, false);
// The path length will be equal to the flood value at the target cell, so
// we can reserve that many elements beforehand.
out.reserve(flood_buffer[p1.x][p1.y]);
// We start at the target cell
P p(p1);
out.push_back(p);
const R map_r(P(0, 0), P(map_w, map_h) - 1);
while (true)
{
const int current_val = flood_buffer[p.x][p.y];
P adj_p;
// Find valid offsets, and check if origin is reached
for (size_t i = 0; i < nr_dirs; ++i)
{
const P& d(dirs[i]);
adj_p = p + d;
if (adj_p == p0)
{
// Origin reached
return;
}
if (map_r.is_p_inside(adj_p))
{
const int adj_val = flood_buffer[adj_p.x][adj_p.y];
// Mark this as a valid travel direction if it is not blocked,
// and is fewer steps from the target than the current cell.
valid_offsets[i] =
(adj_val != 0) &&
(adj_val < current_val);
}
}
// Set the next position to one of the valid offsets - either pick one
// randomly, or iterate over the list and pick the first valid choice.
if (randomize_steps)
{
std::vector<P> adj_p_bucket;
for (size_t i = 0; i < nr_dirs; ++i)
{
if (valid_offsets[i])
{
adj_p_bucket.push_back(p + dirs[i]);
}
}
ASSERT(!adj_p_bucket.empty());
adj_p = rnd::element(adj_p_bucket);
}
else // Do not randomize step choices - iterate over offset list
{
for (size_t i = 0; i < nr_dirs; ++i)
{
if (valid_offsets[i])
{
adj_p = P(p + dirs[i]);
break;
}
}
}
out.push_back(adj_p);
p = adj_p;
} // while
}
