Hello.

Im looking in to the article on the frontpage http://www.gamedev.net/page/resources/_/technical/game-programming/implementing-component-entity-systems-r3382 about component entity systems..

bitwise operations have never been my strong suit,

I am looking at this line here

if((world->mask[entity] & MOVEMENT_MASK) == MOVEMENT_MASK)

in this part

#define MOVEMENT_MASK (COMPONENT_DISPLACEMENT | COMPONENT_VELOCITY)

void movementFunction(World *world)
{
    unsigned int entity;
    Displacement *d;
    Velocity *v;

    for(entity = 0; entity < ENTITY_COUNT; ++entity)
    {
        if((world->mask[entity] & MOVEMENT_MASK) == MOVEMENT_MASK)
        {
            d = &(world->displacement[entity]);
            v = &(world->velocity[entity]);

            v->y -= 0.98f;

            d->x += v->x;
            d->y += v->y;
        }
    }
}

and cant figure out why this is needed.

if((world->mask[entity] & MOVEMENT_MASK) == MOVEMENT_MASK)

couldn't you just put it like this ->

if(world->mask[entity] == MOVEMENT_MASK)

I hope you can help clarify this for me

Best Regards

Morten

ahh I see.

Thank you for the quick response.

Regards