Steve Jackson Games - Site Navigation
Home General Info Follow Us Search Illuminator Store Forums What's New Other Games Ogre GURPS Munchkin Our Games: Home

Go Back   Steve Jackson Games Forums > Roleplaying > GURPS

Reply
 
Thread Tools Display Modes
Old 02-15-2019, 09:56 AM   #1
oneofmanynameless
 
Join Date: May 2012
Location: New Hampshire, USA
Default How do you do a beam?

For a long time I modeled beams with the Jet modifier before finally discovering that you can't use them for spraying fire or covering fire (I had some weird memory about reading somewhere that you could. It was shocking to discover this memory to be false.) But that leaves me with the question of how to model beams of energy.

In video games we typically model a gun that shoots a constant beam of energy as a weapon with an extremely high rate of fire that does very little damage per shot. I typically set the cycle rate to be noticeably above the expected frame-rate, like in the 60 shots per second rate. (If the weapon has a clip size I typically have it read as 1 "shot" = .1 seconds worth of fire typically 6+ shots.) You could do a similar treatment in GURPS, but 1 damage per shot is still (often) way to high while still not giving it armor penetration equivalent to a standard projectile attack if sustained on the same target.

Does anyone have any simple solutions or suggestions? Has this problem already been solved elsewhere?
oneofmanynameless is offline   Reply With Quote
Old 02-15-2019, 11:07 AM   #2
naloth
 
Join Date: Sep 2004
Default Re: How do you do a beam?

You can split rapid RoF weapons. From memory (which may not be totally correct), you must have RoF 5+ and you lose at least 1 shot between targets. The rules are in the Campaigns book.

You can also do something similar with Jets. (Again, from memory) I believe it was covered as a technique in High Tech for flame throwers. Read http://forums.sjgames.com/showpost.p...3&postcount=18

Adding up all the damage against DR is a bit of an artifact from 3e lasers. Under 4e I'd do that as an alternate attack where you have a focus beam that doesn't have a high RoF but does more damage and a different attack with a really high RoF but low damage.

Last edited by naloth; 02-15-2019 at 11:13 AM.
naloth is offline   Reply With Quote
Old 02-15-2019, 11:13 AM   #3
Anthony
 
Join Date: Feb 2005
Location: Berkeley, CA
Default Re: How do you do a beam?

Well, nothing in Innate Attack requires the attacks to be instant; you can do an RoF X attack and declare that each 'shot' is actually 1/X of a second. I would generally recommend RoF 15. You can make it cumulative against DR by giving it armor divisor 10, Limited: cannot exceed the number of hits (this is probably around +150%).
__________________
My GURPS site and Blog.
Anthony is online now   Reply With Quote
Old 02-15-2019, 11:17 AM   #4
Rupert
 
Rupert's Avatar
 
Join Date: Aug 2004
Location: Wellington, NZ
Default Re: How do you do a beam?

Quote:
Originally Posted by oneofmanynameless View Post
In video games we typically model a gun that shoots a constant beam of energy as a weapon with an extremely high rate of fire that does very little damage per shot. I typically set the cycle rate to be noticeably above the expected frame-rate, like in the 60 shots per second rate. (If the weapon has a clip size I typically have it read as 1 "shot" = .1 seconds worth of fire typically 6+ shots.) You could do a similar treatment in GURPS, but 1 damage per shot is still (often) way to high while still not giving it armor penetration equivalent to a standard projectile attack if sustained on the same target.
Video games also typically model armour as either ablative (common for shooters), or providing a percentage reduction in damage taken (common in MMORPGs), which allow low-damage high-RoF attacks to do comparable injury to high-damage low-RoF attacks.

The problem is that GURPS does not, by default, do this. To do this in GURPS you'd have to step back to 3e's method of resolving laser fire where you added all the hits together before rolling damage, which would be an enhancement that you'd have to design yourself, because as far as I know it doesn't exist in 4e.
__________________
Rupert Boleyn

"A pessimist is an optimist with a sense of history."
Rupert is offline   Reply With Quote
Old 02-15-2019, 01:39 PM   #5
Refplace
 
Refplace's Avatar
 
Join Date: Nov 2008
Location: Yukon, OK
Default Re: How do you do a beam?

As others have said the systems your trying to model dont really have DR like GURPS, its either damage reduction or just lots of HP.
Simulating that is best done by an attack that ignores DR.
Options...
Armor Divisor (10) for +200%
Cosmic, Irrestible Attack, +300%
Or Corrosive based attack (10 pts/ per die)
__________________
My GURPS publications GURPS Powers: Totem and Nature Spirits; GURPS Template Toolkit 4: Spirits; Pyramid articles. Buying them lets us know you want more!
My GURPS fan contribution and blog:
REFPLace GURPS Landing Page
My List of GURPS You Tube videos (plus a few other useful items)
My GURPS Wiki entries
Refplace is offline   Reply With Quote
Old 02-15-2019, 03:04 PM   #6
AlexanderHowl
 
Join Date: Feb 2016
Default Re: How do you do a beam?

An interesting thought comes to mind. Would lasers that use a series of microsecond pulses be better represented with a linked corrosive attack since they literally drill into the target? Since corrosion is culumative (otherwise there would be no reason to have a corrosion attack of less than 2d and corrosive attacks would be far too expensive at 10 CP/dice), a linked attack that dealt even one point of corrosive damage could ruin armor pretty quickly with rapid fire.

I think that lasers should have a microsecond pulse option. A single shot would consist of 1000 1-microsecond pulses and would deal linked corrosive damage equal to 1/4 the burning damage (plus the normal burning damage). The armor divisor would be reduced by one step and the option could not be combined with pulse lasers. For example, a Gatling Laser with the microsecond pulse option would deal 3d corrosive damage in addition to 6d×2 burning damage.
AlexanderHowl is offline   Reply With Quote
Old 02-15-2019, 03:18 PM   #7
naloth
 
Join Date: Sep 2004
Default Re: How do you do a beam?

Quote:
Originally Posted by AlexanderHowl View Post
An interesting thought comes to mind. Would lasers that use a series of microsecond pulses be better represented with a linked corrosive attack since they literally drill into the target? Since corrosion is culumative (otherwise there would be no reason to have a corrosion attack of less than 2d and corrosive attacks would be far too expensive at 10 CP/dice), a linked attack that dealt even one point of corrosive damage could ruin armor pretty quickly with rapid fire.
While you could do it that way, it generally works better if you do one innate attack and prioritize either chewing through DR then melting your target or just buy a sufficiently powerful attack to punch through (with or without AD). If you want to flip through those 2 different settings, AAs are fun for that...
naloth is offline   Reply With Quote
Old 02-15-2019, 03:32 PM   #8
Rupert
 
Rupert's Avatar
 
Join Date: Aug 2004
Location: Wellington, NZ
Default Re: How do you do a beam?

Quote:
Originally Posted by AlexanderHowl View Post
An interesting thought comes to mind. Would lasers that use a series of microsecond pulses be better represented with a linked corrosive attack since they literally drill into the target? Since corrosion is culumative (otherwise there would be no reason to have a corrosion attack of less than 2d and corrosive attacks would be far too expensive at 10 CP/dice), a linked attack that dealt even one point of corrosive damage could ruin armor pretty quickly with rapid fire.
Note that while I agree it makes sense for many corrosion attacks to be cumulative, it is not the default. More to the point, in a combat situation corroding armour away is slow, and should only be done if the armour is simply too strong to simply punch through. Take your suggestion below - if we did this with a laser rifle (normally 6d(2)), it would take about ten hits to reduce DR20 armour to the point where the next hit would do the same damage as a hit from the standard 6d(2) weapon. What you actually have with your suggestion is a terror weapon - it's very effective on low-no DR targets, and will cause serious scarring and burns to the victims.

Also, corrosion models the effects of the laser drilling you're talking about badly anyway - corrosion damages the armour over an entire hit location (or at least it's entire facing), whereas the laser is drilling a small but deep hole. This is best represented by a good penetration modifier - something the standard lasers already have, because this is what they are assumed to be doing, though possibly not with quite the pulse rate.
__________________
Rupert Boleyn

"A pessimist is an optimist with a sense of history."

Last edited by Rupert; 02-15-2019 at 06:26 PM.
Rupert is offline   Reply With Quote
Old 02-15-2019, 05:59 PM   #9
Hai-Etlik
 
Hai-Etlik's Avatar
 
Join Date: Jan 2006
Location: Victoria, BC, Canada
Default Re: How do you do a beam?

All else being equal (power, heat dissipation, etc), more energy per shot means less frequent shots and better armour penetration. Given the same resources a laser that fires one brief concentrated pulse is going to be better better at penetrating armour than one that that fires 10 smaller pulses per second, which will be better at it than one that fires as a continuous beam.

Maybe it would make sense to treat them as shotguns or something similar. Movement of the beam over the armour would mean it is now facing fresh armour in the same way that pellets from a shotgun are each facing different portions of the armour.

As the range closes, the linear movement over the surface from a given angular movement (instability, tracking the target, etc) is going to decrease meaning the laser will dwell longer and have more time to burn through the armour in a similar way that shotguns start to "stack" at short range.

One difference is that dodging would decrease the ability to stack. If you are hit by a shotgun shell at close range, I don't think your movement significantly decrease the stacking, but for a laser it probably would.

I don't think corrosion is the right way to go as it suggests the armour as a whole is being weakened. Ordinary attacks that fully penetrate armour will leave holes in it, but we don't generally model those because they are too small to reliably target again and the rest of the armour is still fine (unless enough holes are made to weaken the overall structure) A continuous laser beam failing to penetrate would leave a trail across the armour but it wouldn't benefit on subsequent attacks except where it intersects a previous trail, and to progress beyond that it would have to intersect the intersections. This does gradually get more likely with more attacks but only in the same way that if you hit armour with enough of any attack it will eventually wear down but, that doesn't make all attacks corrosive.

Against an immobile target, a continuous laser at close range would be more like using a drill or cutting torch. Not a useful technique in combat, but if you've disabled an armoured target and need to open it, it becomes far more useful, although I don't think this would necessarily be best modelled as conventional "attacks" in "combat".
Hai-Etlik is offline   Reply With Quote
Old 02-15-2019, 07:14 PM   #10
lwcamp
 
lwcamp's Avatar
 
Join Date: Nov 2004
Location: The plutonium rich regions of Washington State
Default Re: How do you do a beam?

Quote:
Originally Posted by AlexanderHowl View Post
Would lasers that use a series of microsecond pulses be better represented with a linked corrosive attack since they literally drill into the target?
A bullet also literally drills into its target. Should its damage also be corrosive? After all, it leaves at least as big of a hole as a pulsed laser.

Luke
lwcamp is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Fnords are Off
[IMG] code is Off
HTML code is Off

Forum Jump


All times are GMT -6. The time now is 11:26 PM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2024, vBulletin Solutions, Inc.