region.hh

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#pragma once
/*
  region.hh
  data structures supporting multi-resolution ray tracing in world class.
  Copyright Richard Vaughan 2008
*/

#include "stage.hh"

namespace Stg 
{

  // a bit of experimenting suggests that these values are fast. YMMV.
  const int32_t RBITS( 5 ); // regions contain (2^RBITS)^2 pixels
  const int32_t SBITS( 5 );// superregions contain (2^SBITS)^2 regions
  const int32_t SRBITS( RBITS+SBITS );
        
  const int32_t REGIONWIDTH( 1<<RBITS );
  const int32_t REGIONSIZE( REGIONWIDTH*REGIONWIDTH );

  const int32_t SUPERREGIONWIDTH( 1<<SBITS );
  const int32_t SUPERREGIONSIZE( SUPERREGIONWIDTH*SUPERREGIONWIDTH );
        
  const int32_t CELLMASK( ~((~0x00)<< RBITS ));
  const int32_t REGIONMASK( ~((~0x00)<< SRBITS ));
        
  inline int32_t GETCELL( const int32_t x ) { return( x & CELLMASK); }
  inline int32_t GETREG(  const int32_t x ) { return( ( x & REGIONMASK ) >> RBITS); }
  inline int32_t GETSREG( const int32_t x ) { return( x >> SRBITS); }

  // this is slightly faster than the inline method above, but not as safe
  //#define GETREG(X) (( (static_cast<int32_t>(X)) & REGIONMASK ) >> RBITS)
    
  class Cell 
  {
    friend class SuperRegion;
    friend class World;
     
  private:
    std::vector<Block*> blocks[2];      
     
  public:
    Cell() 
      : blocks(), 
    region(NULL)
    { /* nothing to do */ }                 
     
    void RemoveBlock( Block* b, unsigned int index );
    void AddBlock( Block* b, unsigned int index );
    
    inline const std::vector<Block*>& GetBlocks( unsigned int index )
    { return blocks[index]; }
     
    Region* region;  
  };  // class Cell
  
  class Region
  {
    friend class SuperRegion;
    friend class World; // for raytracing
     
  private:
    std::vector<Cell> cells;
    unsigned long count; // number of blocks rendered into this region
     
  public:
    Region();
    ~Region();
     
    inline Cell* GetCell( int32_t x, int32_t y ) 
    {   
      if( cells.size() == 0 )
    {
      assert(count == 0 );
      
      cells.resize( REGIONSIZE );
      
      for( int32_t c=0; c<REGIONSIZE;++c)
        cells[c].region = this;
    } 
      
      return( &cells[ x + y * REGIONWIDTH ] );
    }
         
    inline void AddBlock();
    inline void RemoveBlock(); 
     
    SuperRegion* superregion;   
     
  }; // class Region
  
  class SuperRegion
  {
  private:
    unsigned long count; // number of blocks rendered into this superregion
    point_int_t origin;
    Region regions[SUPERREGIONSIZE];
    World* world;
     
  public:    
    SuperRegion( World* world, point_int_t origin );
    ~SuperRegion();
     
    inline Region* GetRegion( int32_t x, int32_t y )
    { 
      return( &regions[ x + y * SUPERREGIONWIDTH ]);
    }
     
    void DrawOccupancy(void) const;
    void DrawVoxels(unsigned int layer) const;
         
    inline void AddBlock();
    inline void RemoveBlock();      
     
    const point_int_t& GetOrigin() const { return origin; }
  }; // class SuperRegion;
  
        
}; // namespace Stg