ECS.cpp

#include "ECS.h"

ECS::ECS()
{
    Entities.push_back(0);
    FreeEntitiesList.push_back(0);
    EntitiesCount = 0;

    //-- Set Component list masks --//
    InfoComps.Mask     = COMP_INFO;
    PositionComps.Mask = COMP_POSITION;
    SpeedComps.Mask    = COMP_SPEED;
    SpriteComps.Mask   = COMP_SPRITE;

    //-- Store a pointer to each component list --//
    ComponentLists.push_back((ComponentList<CompGeneric>*)&InfoComps);
    ComponentLists.push_back((ComponentList<CompGeneric>*)&PositionComps);
    ComponentLists.push_back((ComponentList<CompGeneric>*)&SpeedComps);
    ComponentLists.push_back((ComponentList<CompGeneric>*)&SpriteComps);
};

ECS::~ECS()
{
};

//----------------------------------------------------
//----- Return the index of a blank entity -----------
//----------------------------------------------------
int ECS::EntityCreate()
{
    int newEntityId = -1;

    if (FreeEntitiesList.size() == 0)
        {
        newEntityId = EntitiesCount;
        EntitiesCount++;
        }
    else
        {
        newEntityId = FreeEntitiesList[FreeEntitiesList.back()];
        FreeEntitiesList.pop_back();
        }

    if (Entities.size() < EntitiesCount)
        Entities.push_back(0);

    return newEntityId;
};

//---------------------------------------------------------
//----- 'Destroy' an entity by setting the mask to blank --
//---------------------------------------------------------
void ECS::EntityDestroy(int EntityId)
{
    for (unsigned int i = 0; i < ComponentLists.size(); i++) // Free all attached components.
        {
        int mappedIndex = ComponentLists[i]->Map[EntityId];
        if (mappedIndex >= 0)
            ComponentLists[i]->Unused.push_back(mappedIndex);
        }

    Entities[EntityId] = COMP_NONE; // Blank out the entity mask.
    FreeEntitiesList.push_back(EntityId); // Add index to free list.
}

//--------------------------------------------------------------------------
//----- RENDER SYSTEM: Draw entities with position ans sprite components ---
//--------------------------------------------------------------------------
void ECS::SystemRender(SDL_Renderer* Renderer)
{
    int64_t renderSysMask = COMP_SPRITE | COMP_POSITION;

    for (int i = 0; i < Entities.size(); i++)
    {
        if ((Entities[i] & renderSysMask) == renderSysMask) // Check entity can be rendered.
        {
            CompPosition* entityPosition = &PositionComps.List[PositionComps.Map[i]]; // Get needed components.
            CompSprite* entitySprite = &SpriteComps.List[SpriteComps.Map[i]];

            SDL_RenderClear(Renderer);
            SDL_RenderCopy(Renderer, entitySprite->Sprite.Image, NULL, NULL); // Render the entity.
            SDL_RenderPresent(Renderer);
        }
    }
}