Flying and ceiling actors

An actor can fly, like a Paragoomba, or hang from the ceiling, like a Swooper. Both need flags on the actor's blueprint and movement functions that differ from a walking actor's.

Flying actors

Set ACTOR_FLAG_FLYING on the blueprint to make the actor airborne:

OVL_DEF_ACTOR() = {
    .flags = ACTOR_FLAG_FLYING,
    // ...
};

Place a flying actor at an air position, such as BTL_POS_AIR_B, in its formation.

Flying actors use different movement functions than ground actors:

Ground function	Flying equivalent
RunToGoal	FlyToGoal
IdleRunToGoal	IdleFlyToGoal

// flying movement (in EVS_Idle or EVS_TakeTurn)
Call(SetActorSpeed, ACTOR_SELF, 6.0)
Call(FlyToGoal,
    ACTOR_SELF, 0, -4, EASING_LINEAR)

The second argument to FlyToGoal is how many frames the move takes; 0 works it out from the actor's speed. The third is the height of the arc the actor flies along, and a negative height makes it dip downward. The fourth is the easing function.

Knockdown

A jump or a POW attack can knock a flying actor to the ground, if the part it hits has ACTOR_EVENT_FLAG_GROUNDABLE in its .eventFlags:

ActorPartBlueprint ActorParts[] = {
    {
        .flags = ACTOR_PART_FLAG_PRIMARY_TARGET,
        .index = PRT_FLYING,
        // ...
        .eventFlags = ACTOR_EVENT_FLAG_GROUNDABLE,
    },
};

When such an attack hits that part, the actor receives EVENT_FALL_TRIGGER in place of EVENT_HIT. Handle it in EVS_HandleEvent to start a knockdown:

CaseEq(EVENT_FALL_TRIGGER)
    SetConst(LVar0, PRT_FLYING)
    SetConst(LVar1, ANIM_Paragoomba_Hurt)
    ExecWait(EVS_Enemy_Hit)
    ExecWait(EVS_KnockDown)

A knockdown usually involves:

• Swapping visible parts, such as hiding the flying body and showing the grounded body.
• Clearing the ACTOR_FLAG_FLYING flag.
• Changing the status table.
• Moving the actor's home position to the ground tier.
• Binding EVT scripts for the downed actor.

For a complete flying-to-grounded transition, see battle/actor/paragoomba.c.

Ceiling actors

Set ACTOR_FLAG_UPSIDE_DOWN to make an actor hang from the ceiling:

OVL_DEF_ACTOR() = {
    .flags = ACTOR_FLAG_UPSIDE_DOWN,
    // ...
    .statusIconOffset = { -10, -20 },
    .statusTextOffset = { 10, -20 },
};

Place a ceiling actor at a top position, such as BTL_POS_TOP_B, in its formation. The status offsets in this example are Swooper's, which put its status icons below it. Choose offsets that suit your actor's sprite.

You can clear the flag at runtime when the actor drops from the ceiling:

// drop from the ceiling
Call(SetActorFlagBits,
    ACTOR_SELF, ACTOR_FLAG_UPSIDE_DOWN, false)

Ceiling and spiky

Ceiling actors are often spiky. For example, Spike Top's blueprint uses both ACTOR_FLAG_UPSIDE_DOWN and ACTOR_EVENT_FLAG_SPIKY_TOP:

OVL_DEF_ACTOR() = {
    .flags = ACTOR_FLAG_UPSIDE_DOWN,
    // ...
};

ActorPartBlueprint ActorParts[] = {
    {
        // ...
        .eventFlags = ACTOR_EVENT_FLAG_SPIKY_TOP | ACTOR_EVENT_FLAG_FLIPABLE,
    },
};

Spike Top can start on the ceiling or on the ground, depending on its formation's .var0. Its EVS_Init reads that variable, and if Spike Top starts on the ground, clears ACTOR_FLAG_UPSIDE_DOWN. On the ceiling, it clears ACTOR_EVENT_FLAG_FLIPABLE, so it can only be flipped on the ground.

For ceiling actor examples, see battle/actor/swooper.c and battle/actor/spike_top.c.