source/game/component.h

   1 #ifndef MSP_GAME_COMPONENT_H_
   2 #define MSP_GAME_COMPONENT_H_
   3
   4 #include <msp/time/timedelta.h>
   5 #include "accessguard.h"
   6 #include "handle.h"
   7 #include "mspgame_api.h"
   8
   9 namespace Msp::Game {
  10
  11 class Entity;
  12
  13 class MSPGAME_API Component
  14 {
  15 protected:
  16         Handle<Entity> entity;
  17
  18         Component(Handle<Entity>);
  19 public:
  20         virtual ~Component() = default;
  21
  22         Handle<Entity> get_entity() const { return entity; }
  23 };
  24
  25 template<typename T>
  26 class BufferedComponent: public Component
  27 {
  28 public:
  29         using Data = T;
  30
  31 protected:
  32         T data[2];
  33         uint8_t read_index = 0;
  34         uint8_t write_index = 0;
  35         bool written = false;
  36
  37         BufferedComponent(Handle<Entity> e): Component(e) { }
  38
  39         const T &read() const;
  40         T &write();
  41
  42 public:
  43         virtual void prepare_tick() { write_index = 1-read_index; written = false; }
  44         virtual void commit_tick() { if(written) read_index = write_index; }
  45 };
  46
  47 template<typename T>
  48 const T &BufferedComponent<T>::read() const
  49 {
  50 #ifdef DEBUG
  51         AccessGuard::get_instance().check<AccessGuard::Read<T>>();
  52 #endif
  53         return data[read_index];
  54 }
  55
  56 template<typename T>
  57 T &BufferedComponent<T>::write()
  58 {
  59 #ifdef DEBUG
  60         AccessGuard::get_instance().check<AccessGuard::Write<T>>();
  61 #endif
  62         if(!written && write_index!=read_index)
  63         {
  64                 data[write_index] = data[read_index];
  65                 written = true;
  66         }
  67         return data[write_index];
  68 }
  69
  70 } // namespace Msp::Game
  71
  72 #endif