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