Tesla line

What it is

A tesla line is a shared weapon behavior that spawns two energy balls travelling forward together while drifting apart perpendicular to the fire direction. The damage hitbox is the line segment connecting the two balls — any enemy whose body overlaps that segment takes a tick of damage, gated by a per-enemy contact cooldown. It is the geometry behind the energy-family premium weapons that read as a stretched electric tether sweeping across the battlefield.

Geometry

The behavior locks a fire direction at spawn and then drives two balls outward from that axis on each frame.

Step	What the behavior does
1	Lock a forward angle from the ship’s aim at spawn; this angle never changes for the life of the bullet
2	Move the bullet’s midpoint forward along the locked angle at the configured forward speed
3	Each frame, advance a perpendicular spread offset by the spread speed, capped at the maximum spread
4	Place ball 1 at midpoint + perpendicular × spread and ball 2 at midpoint − perpendicular × spread
5	Inflate the bullet’s collision radius to cover the full ball-to-ball distance so the spatial grid still returns nearby enemies
6	Emit spark particles at random points along the segment for the electric-arc visual
7	On bullet expiry, burst spark particles at both ball positions

The perpendicular axis is the 90° CCW rotation of the forward axis, so the two balls always fly to the left-hand and right-hand sides of the firing direction. The maximum spread is the orbit-radius stat; the spread speed is the orbit-speed stat. The behavior caches the per-frame ball positions on the bullet so the collision resolver can read them directly.

Quantity	Source
Forward axis	Locked at spawn from ship aim
Perpendicular axis	90° CCW of forward axis
Forward speed (px/s)	Projectile-speed stat
Spread speed (px/s)	Orbit-speed stat
Maximum spread per ball (px)	Orbit-radius stat
Ball-to-ball segment length (px)	Twice the current spread

Hit resolution

A dedicated collision routine fires every frame the bullet is alive. It treats the ball-to-ball line as a thick segment and damages any enemy whose body overlaps it.

Step	What the resolver does
1	Read the two cached ball positions from the bullet
2	Bail out if the segment is degenerate (length below 1 px)
3	Query the spatial grid for enemies near the segment midpoint with a radius of segment length / 2 + thickness + 30
4	For each candidate, project the enemy centre onto the segment and clamp the projection to the segment endpoints
5	Compute the distance from the enemy centre to that nearest point on the segment
6	If the distance is below line thickness + enemy collision radius and the enemy is not on per-enemy cooldown, damage the enemy and start a fresh cooldown entry
7	Spawn a spark burst at the impact point and run the standard impact-VFX hook

Newly-spawned enemies are skipped while their spawn timer is still under the global spawn-immunity window. Enemies frozen for lag-pause handling are also skipped. The bullet’s per-enemy cooldown map is initialised on first frame and survives until the bullet is recycled.

Quantity	Value
Default line thickness (px)	6
Default per-enemy contact cooldown (seconds)	0.3
Spawn-immunity skip window (seconds)	0.15
Spatial-grid query buffer beyond half-segment (px)	thickness + 30
Sparks per impact burst	3
Impact-spark colour	Bullet’s primary colour

Both tesla-line weapons override the default cooldown to 0.08 s, so each enemy can take up to ~12 ticks per second while a segment hovers across it.

Which weapons use it

Two epic energy weapons share the tesla-line behavior; their stats diverge but the geometry and hit resolution are identical.

Weapon	Family	Damage tag	Collision mode	Per-enemy cooldown (seconds)
Line	Projectile	Energy	Pierce all	0.08
Magnetar	Projectile	Energy	Pierce all	0.08

Both weapons aim at the closest enemy, can hit destructibles, and use the line-spread area mode for the in-game range indicator.

Stat	Line (L1)	Line (L20)	Magnetar (L1)	Magnetar (L20)
Damage per tick	31.2	131.80	42.0	152.2
Fire rate (shots/s)	0.20	0.667	0.15	0.53
Projectile speed (px/s)	120	177	100	147.5
Projectile size (px)	14	25.4	18	31.3
Maximum spread per ball (px)	55	170	85	237
Spread speed (px/s)	30	45.2	25	38.3
Acquire range (px)	220	296	350	464
Travel-range multiplier	3.0	3.0	5.0	5.0
Warmup (seconds)	0	0	0.10	0.10

Line reads as a quick electric-blue strike with a tight initial spread. Magnetar reads as a heavier violet-magenta tether: slower fire rate and slower spin but wider final spread, longer travel range, longer acquire range, and a brief warmup before the first cast.

EXTRACT-CANDIDATEs

• EXTRACT-CANDIDATE: spawn-immunity window — the global _spawnT > 0.15 skip used by every contact-cooldown collision routine; deserves its own concept page so per-weapon docs stop redescribing it.
• EXTRACT-CANDIDATE: lag-pause _frozenForLag enemy flag — a global skip used by tesla-line, cone-beam-dot, and other DOT-style resolvers; pair with the spawn-immunity page.
• EXTRACT-CANDIDATE: spatial-grid candidate-list fallback (candidates.length > 0 ? candidates : enemies) — a recurring resolver pattern that handles unit-test paths which bypass the grid; useful for the combat page.
• EXTRACT-CANDIDATE: point-to-line-segment distance helper (project onto segment, clamp to endpoints, hypot to nearest point) — re-implemented inline in this resolver and could become a shared geometry primitive shared with future tether weapons.
• EXTRACT-CANDIDATE: bullet-radius inflation for spread weapons (b.rad = max(ballRadius, spread + 10)) — a workaround so the spatial grid still returns nearby enemies once the visible hitbox is wider than the underlying bullet entity; relevant for any future two-body weapon.
• EXTRACT-CANDIDATE: impact-spark colour derived from b.c1 hex slice — the resolver parses the bullet’s primary hex colour into RGB inline; a shared “bullet colour → RGB” helper would let other resolvers stop repeating the slice math.