Homing Missiles (lock-on + scripted flight)

GTA-style vehicle homing rockets built entirely in code — no XML projectile, no asset bundle. Reference implementation: Oppressor/src/OppressorRockets.cs (lock-on system + IMGUI detection box + scripted missile), wired from EntityOppressor.OnUpdateLive. The turret-style ancestor is RocketTurret/src/RocketTurretLaunchManager.cs — note its ExplosionServer call and flat Explosion.* props are 2.x-era and silently broken on 3.0.0 (see Runtime Explosions (ExplosionData)).

Scripted missile (MonoBehaviour, no Entity)

A plain GameObject + MonoBehaviour, keeping its own world-space position and stamping transform.position = worldPos - Origin.position each frame (origin reposition — see Entity Positions).

Per frame:

1. Speed ramp (MoveTowards toward max) — launch feel.
2. Homing: dir = Vector3.RotateTowards(dir, (aimPoint - worldPos).normalized, turnRateRad * dt, 0f). Capped turn rate (~165°/s) is what makes fast crossing targets dodgeable. Aim point = target.position + up * max(0.8, target.height * 0.55).
3. Proximity fuse: detonate within ~2 m of the aim point (covers frame-step overshoot at 50 m/s).
4. Collision: Voxel.Raycast(world, new Ray(worldPos, dir), step + 0.35f, -538750997, 8, 0f) — world coords in, Voxel.voxelRayHitInfo.hit.pos world coords out; this mask hits terrain, blocks, AND entity colliders, so direct hits detonate too. Pull the blast back along dir ~0.12 m so the explosion sphere isn't buried in the surface.
5. Arm delay (~0.1 s of no collision checks) so the rocket clears the launching vehicle's own colliders.
6. Lifetime cap → detonate airborne (reads better than despawning).

Detonation = 3.0.0-style ExplosionData (nested "Explosion" class via props.SetValue("Explosion", key, value)) + ExplosionServer(worldPos, World.worldToBlockPos(worldPos), Quaternion.identity, data, ownerEntityId, 0f, false, null). Frag-style tuning (high EntityDamage/RadiusEntities, low block damage) keeps horde-strafing from cratering bases/POIs.

Vanilla assets to reuse (no bundle needed)

• Rocket visual: @:Other/Items/Weapons/Ranged/RocketLauncher/rocketPrefab.prefab via DataLoader.LoadAsset<GameObject>. Nose is +Z (matches Quaternion.LookRotation(velocity)). Must: destroy MonoBehaviours whose type name contains Projectile/Rocket/Mover (they'd drive their own flight), destroy Rigidbodies, disable colliders, then SetActive(true) every child (smoke/flame ship inactive; the launcher item normally activates them) and Play() all particle systems.
• Launch bang: sounds.xml node m136_fire (GameManager.PlaySoundAtPositionServer(pos, "m136_fire", AudioRolloffMode.Logarithmic, 80, 1f) — 3.0 has a trailing _volumeScale).
• Flight loop: the raw clip is loadable directly — DataLoader.LoadAsset<AudioClip>("@:Sounds/Weapons/Ranged/M136/m136_rocket_lp.wav") onto your own looping 3D AudioSource (dopplerLevel ~0.6 gives the flyby whoosh). Loading .wav assets by @: path works for any sounds.xml clip.
• Explosion visual: ParticleIndex 5 = vanilla ammoRocketHE blast (vanilla HE profile for reference: EntityDamage 420, RadiusEntities 4, BlockDamage 2500, RadiusBlocks 5).

Lock-on system

• Acquisition: candidates from world.GetEntitiesInBounds(typeof(EntityAlive), bounds, list); filter class (EntityEnemy subtree covers zombies — EntityZombie : EntityHuman : EntityEnemy — and hostile animals via EntityEnemyAnimal : EntityEnemy; add EntityAnimal for wildlife; players/ NPCs/traders excluded by not being either). Pick the smallest angle from rider.cameraTransform.forward inside an acquire cone (~15°), range ~90 m.
• Sticky hold: once locked, keep the target while it stays in a wider cone (~26°) and range ×1.15, and give cone/LOS failures a ~0.3 s grace window before dropping — otherwise the box flickers on every fence post.
• LOS from the vehicle, not the camera: a 3rd-person camera ray passes through the vehicle's own E_Vehicle collider (and the rider) every frame. Cast from vehicle center offset ~2.4 m along the ray (clears a bike-sized collider's half-diagonal), stop ~0.7 m short of the target so its own collider isn't counted as an occluder.
• Lock progress: same target held → progress += dt / 0.85s; new target resets. progress >= 1 = locked.
• Run all of this per frame in a persistent MonoBehaviour, not in the entity's 20 Hz tick — Input.GetMouseButtonDown edges land on frames the entity doesn't tick, and the HUD box needs per-frame tracking. The vehicle registers itself each tick (RegisterActive(bike, rider) + timestamp) and the runtime treats a stale timestamp (>0.3 s) as dismounted — no explicit teardown paths needed.

Detection box HUD (IMGUI)

Project the 8 corners of position ± width/2 × height (world − Origin.position) through rider.playerCamera.WorldToScreenPoint; bail if any corner z <= 0; GUI y = Screen.height - screenPoint.y. Take min/max for the rect. GTA feel:

• While acquiring: white brackets, oversized ×1.6 shrinking to ×1.0 with lock progress, alpha blinking with the same period as the beep loop.
• Locked: solid red with a fast subtle pulse.
• Draw as 4 corner L-brackets + a 25 %-alpha 1 px full outline (1×1 solid Texture2D cache pattern from IMGUI Tracker Stack).

Synthesized lock-on audio (no ripped assets)

Both states are looping AudioClip.Create clips on one 2D AudioSource (spatialBlend 0); switching the clip on state change restarts the loop:

• Acquiring beeps: one clip = short blip + silence (e.g. 65 ms @ 1170 Hz sine with 4 ms attack / 14 ms release envelope, in a 0.32 s buffer), looped — beep cadence = clip length, no timers.
• Locked tone: continuous sine loop that's seamless because the loop length holds an exact integer number of cycles (1560 Hz × 0.25 s = 390 cycles; add a 2nd harmonic at half amplitude-ish for an "avionics" timbre — also integer cycles). No crossfade needed.

Same AudioClip.Create/SetData approach as the Oppressor's jet loop and Synthesized Drone Rotor Audio.