texture_atlas.h

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#ifndef YAZE_APP_GFX_TEXTURE_ATLAS_H
#define YAZE_APP_GFX_TEXTURE_ATLAS_H
 
#include <map>
#include <memory>
#include <vector>
 
#include "app/gfx/bitmap.h"
#include "absl/status/status.h"
 
namespace yaze {
namespace gfx {
 
class TextureAtlas {
 public:
  struct AtlasRegion {
    int x = 0;           // X position in atlas
    int y = 0;           // Y position in atlas
    int width = 0;       // Region width
    int height = 0;      // Region height
    int source_id = -1;  // ID of source (e.g., room_id)
    bool in_use = false; // Whether this region is allocated
  };
  
  explicit TextureAtlas(int width = 2048, int height = 2048);
  
  AtlasRegion* AllocateRegion(int source_id, int width, int height);
  
  absl::Status PackBitmap(const Bitmap& src, const AtlasRegion& region);
  
  absl::Status DrawRegion(int source_id, int dest_x, int dest_y);
  
  void FreeRegion(int source_id);
  
  void Clear();
  
  Bitmap& GetAtlasBitmap() { return atlas_bitmap_; }
  const Bitmap& GetAtlasBitmap() const { return atlas_bitmap_; }
  
  const AtlasRegion* GetRegion(int source_id) const;
  
  int width() const { return width_; }
  int height() const { return height_; }
  
  struct AtlasStats {
    int total_regions = 0;
    int used_regions = 0;
    int total_pixels = 0;
    int used_pixels = 0;
    float utilization = 0.0f;  // Percentage of atlas in use
  };
  AtlasStats GetStats() const;
 
 private:
  int width_;
  int height_;
  Bitmap atlas_bitmap_;  // Large combined bitmap
  
  // Simple linear packing for now (future: more efficient algorithms)
  int next_x_ = 0;
  int next_y_ = 0;
  int row_height_ = 0;  // Current row height for packing
  
  // Map source_id → region
  std::map<int, AtlasRegion> regions_;
  
  // Simple rect packing helper
  bool TryPackRect(int width, int height, int& out_x, int& out_y);
};
 
}  // namespace gfx
}  // namespace yaze
 
#endif  // YAZE_APP_GFX_TEXTURE_ATLAS_H