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Systems

Failure & wreck

At 0 % hull the walker does not just turn into a wreck. One side gives way, it collapses, burns and throws sparks – and seven seconds later it goes up in a huge explosion.

In plain wordsWhen the hull reaches zero, the server sets one replicated number. Every machine then plays the same collapse and effects by itself. After seven seconds the server sets off the explosion and tells every nearby player to show it.

Flow

Hull 0 %→Server: state 1 + seed→Every machine: collapse pose + effects→7 s: warhead + broadcast→Vanilla wreck

One replicated state, local show

Only two small values travel over the network: a state (0 intact, 1 collapsing, 2 exploded) and a random seed that picks the side that gives way first. Every machine plays the rest from these. A player who joins after the explosion gets state 2 directly and sees the wreck lying – without replaying the sequence.

Example code – free to use

[RplProp(onRplName: "OnWreckRpl")]
protected int m_iWreck;			// 0 intact, 1 collapsing, 2 exploded
[RplProp(onRplName: "OnWreckRpl")]
protected int m_iWreckSeed;
protected int m_iWreckSeen;

void ServerStartWreck()
{
	if (m_iWreck != 0)
		return;

	m_iWreck = 1;
	m_iWreckSeed = Math.RandomInt(1, 1000000);
	Replication.BumpMe();
	OnWreckRpl();				// the server gets no callback for its own change
	GetGame().GetCallqueue().CallLater(ServerExplode, 7000, false);
}

protected void OnWreckRpl()
{
	if (m_iWreck == m_iWreckSeen)
		return;

	int before = m_iWreckSeen;
	m_iWreckSeen = m_iWreck;

	bool instant = before == 0 && m_iWreck == 2;	// joined after the explosion
	m_Rig.SetWreck(true, m_iWreckSeed, instant);
	if (!instant && before == 0 && !System.IsConsoleApp())
		StartEffectTimeline();				// sparks, smoke, impact sound, fire
}

NoteA Game Master "Destroy" sets the vanilla hit zone straight to 0. Watch for the DESTROYED state as well and play the sequence anyway.

The collapse is a pose

No animation clip: the collapse is laid on top of the existing park crouch. First a stagger (one side gives way, a short knee jerk), then a fall that accelerates like a free fall into a deeper, nose-down, rolled pose, ending with a kick into the impact spring. The stabilizer adds a forward slump to the torso and lets the arms hang.

Example code – free to use

m_fWreckT += dt;
float stagger = Math.Clamp(m_fWreckT / 1.0, 0, 1);
stagger = stagger * stagger * (3 - 2 * stagger);		// smoothstep
float u = Math.Clamp((m_fWreckT - 1.0) / 1.1, 0, 1);
float fall = u * u;						// accelerating like a free fall

m_fParkBlend = Math.Max(m_fParkBlendAtStart, 0.25 * stagger + 0.75 * fall);
m_fWreckBlend = fall;
m_fWreckRoll = 0.45 * stagger + 0.55 * fall;

// posture = park crouch + wreck: deeper, nose down, rolled to the side that gave way
float pitch = m_fParkPitch * m_fParkBlend + 14 * m_fWreckBlend;
float roll = m_fWreckSide * 11 * m_fWreckRoll;
vector offset = m_vParkOffset * m_fParkBlend + Vector(0, -1.4, 0.6) * m_fWreckBlend;

NoteBecause the wreck counts as a park wish, the existing park lock already blocks walking and firing – no extra checks in the drive or the weapons.

The big explosion has to reach everyone

PitfallA warhead that the server spawns and triggers explodes on the server. In the first test the clients saw the collapse but no explosion at all.

The fix is the same path the missiles use: the server sends effect and sound to every player near the walker through that player's own PlayerController (players with the Game Master editor open get it too). The warhead still does the damage on the server.

Example code – free to use

// server
vector centre = TorsoCentre();
MyWalker_Blast(WARHEAD, centre, lastAttacker);		// damage, server only
foreach (SCR_PlayerController pc : PlayersNear(centre, 2000))
	pc.MyWalker_SendDetonation(centre, BIG_EFFECT, BIG_SOUND, 4.0);	// picture and sound, every client

The crew

Whoever is still aboard dies with the explosion and is thrown out. The seats sit on child turret entities, so walk the children. Remember the last attacker of the hull and use it as instigator – that keeps the kill credit.

Example code – free to use

protected void KillCrew(IEntity ent, Instigator who, int depth)
{
	if (!ent || depth > 6)
		return;

	SCR_BaseCompartmentManagerComponent seats = SCR_BaseCompartmentManagerComponent.Cast(ent.FindComponent(SCR_BaseCompartmentManagerComponent));
	if (seats)
		seats.KillOccupants(who, true);		// eject the bodies

	IEntity child = ent.GetChildren();
	while (child)
	{
		KillCrew(child, who, depth + 1);
		child = child.GetSibling();
	}
}