njin_spatial.h

#pragma once
#include "_math.h"
#include "_types.h"
#include <memory>
#include <vector>
 
namespace njin {


enum spatial_kind : u8 {
  spatial_grid,
  spatial_quadtree,
};

struct spatial_item {
  vec2 pos{};        
  f32 radius = 0.0f; 
  u32 group = 0;
  bool fixed = false;
};

struct spatial_desc {
  spatial_kind kind = spatial_grid; 
  rect bounds{};
  f32 cell_size = 0.0f;
  u32 leaf_size = 8;  
  u32 max_depth = 12; 
};
 
struct spatial_impl;

struct spatial_index {
  spatial_index();  
  ~spatial_index(); 
  spatial_index(spatial_index &&) noexcept;            
  spatial_index &operator=(spatial_index &&) noexcept;
  std::unique_ptr<spatial_impl> impl; 
};

void spatial_build(spatial_index &index, const spatial_desc &desc, const spatial_item *items, u32 count);

inline void spatial_build(spatial_index &index, const spatial_desc &desc, const std::vector<spatial_item> &items) {
  spatial_build(index, desc, items.data(), (u32)items.size());
}

u32 spatial_size(const spatial_index &index);

struct spatial_query {
  vec2 at{};         
  f32 radius = 0.0f;
  bool touching = false;
  u32 skip = 0xFFFFFFFFu; 
  u32 group = 0;          
  bool (*filter)(u32 item, void *user) = nullptr;
  void *user = nullptr; 
};

struct spatial_hit {
  u32 item = 0;           
  f32 distance_sq = 0.0f; 
};

u32 spatial_nearest(const spatial_index &index, const spatial_query &q, spatial_hit *out, u32 k);

inline u32 spatial_nearest(const spatial_index &index, const spatial_query &q, std::vector<spatial_hit> &out, u32 k) {
  out.resize(k);
  const u32 n = spatial_nearest(index, q, out.data(), k);
  out.resize(n);
  return n;
}

u32 spatial_separate(const spatial_index &index, std::vector<vec2> &push, u32 k = 6);
} // namespace njin