Laser Fence

Create powered posts that fill the gap between them with a wall of laser beams. Put them in a line, give them power, and once they've charged, the beams switch on and keep enemies out. You can also make laser gates that will open for you to walk through.

What it does

Fences from posts: a post links to the next post in line, up to 12 tiles apart, with three beams between them. Beams block biters, characters, vehicles and buildings. Trains pass through, and belts can run underneath.
Burns what bites it: whatever attacks a beam from close by takes 5 laser damage per hit back, more with laser damage research. Enemies standing in the gap when a fence switches on are burnt.
Drops when broken, comes back: a beam has 200 health and heals 5 a second. If one is broken, the beams between those two posts drop until both posts have recharged, a few seconds. Short of power, a post's beams drop and come back once it's charged again.
Laser gates: between two gate posts the beams open for your own side, like a vanilla gate, and stay shut for everyone else.
Crossings and splits: fences can cross at right angles. Placing a post inside a fence splits it in two.
Quality: beams get the health of the lower-quality post of the two, 30% more a quality level.

Building

Drag building: drag a line of posts and one is placed each time the gap reaches the post's reach, range research included. No post lands at the very end of a drag or on a corner; click those in by hand.
Reach preview: while you hold a post, each of your posts nearby shows a dashed line along its row and column out to how far it reaches, with a square on the furthest tile a new post would still link from.
Status on hover: a post shows whether it's charging, how many fences it holds, that it's waiting for a charged post in reach, or what's in the way. Something blocking a fence is also named in a message where it is, and the fence forms once it's gone.
Power: a post draws 400 kW plus 10 kW for each tile of beam, shared by the posts at its ends. A post holding no beams draws a tenth of its own power.
Undo, blueprints, copy and paste, and construction robots all work as with any building.

Research

Laser fence: after Laser and Military science pack. A post: 10 steel plates, 5 advanced circuits, 5 batteries.
Laser gate: after Laser fence. A gate post: a laser fence post and 2 electronic circuits.
Laser fence range (3 levels): +3 tiles of reach each.
Laser fence efficiency (3 levels): -25% of a post's own power each.

Settings

All startup settings: reach between posts (12), reach added per range level (3), power per post (400 kW) and per beam tile (10 kW), beam health (200), damage back to attackers (5 per hit, 0 for none), and whether laser damage research raises it (on, at three quarters of what it gives laser turrets).

Good to know

On Gleba, strafers and stompers step over a laser fence, as they step over walls. Wrigglers get through a laser gate, as they get through walls, but not through a laser fence.
On Vulcanus, a demolisher crushes posts and beams in its way, like everything else on its route.
Works with Squeak Through 2 and SmoothStart's "squeeze through tight gaps": posts and beams keep their full size, so nothing slips past them.
Works with or without Space Age.
Can't run alongside the original Laser Fence, which does the same job.

Thanks

The idea comes from Laser Fence by randomflyingtaco and Sacredanarchy, which runs on Factorio 2.0. This is a new mod with its own code and art.