package phys

Vec2 :: [2]f32

Rect :: struct {
  start: Vec2,
  size: Vec2,
}

Layer :: enum (u16) {
  Default,
  Hard, // hard collisions; don't let bodies intersect at all
  Soft, // soft collisions; push away other bodies with a force
  Enemy, // enemy hitboxes
  Player, // player hitboxes
  Enemy_Projectile,
  Player_Projectile,
}

Collision_Type :: enum (u8) {
  Up,
  Down,
  Right,
  Left,
  Horizontal,
  Vertical,
}

Body :: struct {
  handle: Body_Handle,
  bin_idx: i32,
  rect: Rect,
  active: bool,
  pos: Vec2,
  vel: Vec2,
  collisions: bit_set[Collision_Type;u8],
  layers: bit_set[Layer;u16],
  mask: bit_set[Layer;u16],
}

make_body :: proc(
  rect: Rect,
  layers := bit_set[Layer;u16]{.Default},
  mask := bit_set[Layer;u16]{.Default},
) -> Body_Handle {
  b := Body {
    rect   = rect,
    layers = layers,
    mask   = mask,
    active = true,
  }
  return add_body(b)
}

aabb_hori :: proc(a: Rect, b: Rect) -> bool {
  return a.start.x < b.start.x + b.size.x && b.start.x < a.start.x + a.size.x
}

aabb_vert :: proc(a: Rect, b: Rect) -> bool {
  return a.start.y < b.start.y + b.size.y && b.start.y < a.start.y + a.size.y
}

aabb :: proc(a: Rect, b: Rect) -> bool {
  return aabb_hori(a, b) && aabb_vert(a, b)
}