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Legacy:Laser Trip Bomb

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What Is A Laser Trip Bomb?

This is basically a laser that is projected across a hallway and explodes when you cross it.

How Do I Make One?

Mover template

Make a small cyclinder brush which covers across the hallway, a radius of 8 is good. Rotate it sideways so it is across the hallway. Then press the "Add special brush" icon and make a masked decoration but make it a non solid.

the VolumetricBuilder would make a nice laser effect and would look more 3D

Now the brush is done open up the texture browser and find texture pack uttech3 and use the laser texture.


Okay thats the look of the laser now we have to make it a mover, because it should disappear when you trigger it. Create a mover from the template. Delete the template (or move it away somewhere else) and rebuild.

Now we have to set up the laser mover:

  • Events -> Tag = laser
  • Dynamiclightmover: Set it if you want the laser to look good.
  • Triggeronceonly: Set it so it only blows up once
  • MoverEncroachType: Another just in case, set to ignore, because if the player hits the mover it will reset, not a good looking idea
  • MoveTime: The trip wire lasers should disappear exactly when its triggered, so set move time to 0
  • InitialState : Set to TriggerOpenTimed

Set its keyframe 1 out of the map: this is so it disappears when activated.


Set up a SpecialEvent as follows. Further options (such as death messages) are explained on the page for that actor.

  • Events -> Tag = laser
  • If you want the player to die immediately set intitalstate to Killinstigator, but if you want a specified amount of damage, set it to damage instigator.
  • Damage: Thats a fair amount, and you can always leave a die message if you want.

Adding explosion

Add an Actor >> Effects >> ExplosionChain. Add it on the wall or something so it looks like the bomb are on the wall.

  • Onlytriggerable: True
  • Tag: laser
  • Size: Might wanna increase the explosion a bit, set it to 4 instead of 1, and set delay time to 0.1

You could also add more explosion chains, it looks a bit tame with only 1 ingame, I suggest add 1 on each site and set explosion size to 4


Now add a few triggers to cover the length of the laser and set their Event to "laser" and triggerable only once = true


Wormbo: This could also be coded as a Projectile (UT) subclass for the bomb and an Effects (UT) subclass for the laser which works like the Pulsegun beam. Either the laser effect parts trigger the bomb in their Touch function or the bomb actor uses Trace or ForEach TraceActors(...) to check whether something goes through the laser beam.

Tarquin: Yeah, I've always figured there's a lot that could be done with Pulsegun-style beams.

Darkwarrior: Does anyone know how you would make something like this as a weapon? Or even if it can be done? (e.g. The tripmines in Half-life)

Daid303: Look for weaponsfactory (UT mod) it has a trip mine, and a good one too.

Darkwarrior: Yes, I've seen the tripmine in that mod but there are two problems. It isnt a weapon and it doesnt explode. If i knew more about Uscript then that wouldnt be a problem, but I know stuff all so it is a problem.

Zygar: I'm going to make a trip mine once I've learned uscript.

Darkwarrior: And I bet it will never get finished, just like all the supposedly awesome maps you keep telling me about.