The next little game in the series where I make a fancy rogue game.
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roguish/collider.cpp

62 lines
1.7 KiB

#include "collider.hpp"
#include <fmt/core.h>
using namespace fmt;
using DinkyECS::Entity;
void SpatialHashTable::insert(Point pos, Entity ent) {
table[pos] = ent;
}
void SpatialHashTable::remove(Point pos) {
table.erase(pos);
}
void SpatialHashTable::move(Point from, Point to, Entity ent) {
remove(from);
insert(to, ent);
}
bool SpatialHashTable::occupied(Point at) const {
return table.contains(at);
}
/*
* Avoid doing work by using the dy,dx and confirming that
* at.x or at.y is > 0. If either is 0 then there can't be
* a neighbor since that's out of bounds.
*/
inline void find_neighbor(const PointEntityMap &table, FoundList &result, Point at, int dy, int dx) {
// don't bother checking for cells out of bounds
if((dx < 0 && at.x <= 0) || (dy < 0 && at.y <= 0)) {
return;
}
Point cell = {at.x + dx, at.y + dy};
auto it = table.find(cell);
if (it != table.end()) {
result.insert(result.end(), it->second);
}
}
std::tuple<bool, FoundList> SpatialHashTable::neighbors(Point cell, bool diag) const {
FoundList result;
// just unroll the loop since we only check four directions
// this also solves the problem that it was detecting that the cell was automatically included as a "neighbor" but it's not
find_neighbor(table, result, cell, 0, 1); // north
find_neighbor(table, result, cell, 0, -1); // south
find_neighbor(table, result, cell, 1, 0); // east
find_neighbor(table, result, cell, -1, 0); // west
if(diag) {
find_neighbor(table, result, cell, 1, -1); // south east
find_neighbor(table, result, cell, -1, -1); // south west
find_neighbor(table, result, cell, 1, 1); // north east
find_neighbor(table, result, cell, -1, 1); // north west
}
return std::tuple(!result.empty(), result);
}