Feasibility of Extensible Booms

[Kibble]

What the title said. Is it possible within the realm of KSP code to have a part that extends out (and reels back in) such that attached parts move with it?

[Tex_NL]

Infernal Robotics

[ultrasquid]

Yes, there are parts that do exactly that in the Infernal Robotics mod.

[Kibble]

Oh right. I found IR to be egregiously complex though.

I would love to create a mod adding simple (but length-tweakable!) booms, an ATK-style coilable boom, and one (surface-attachable?) truss styled after Space Station solar array mast. However, considering I have only a little experience coding (and not in C++!) so a little uh...guidance...would be great.

Anyone? <3

[tater]

Yeah, I'd be all for a simple implementation of this kind of thing. I never even considered IR, looked like just too much stuff.

[Kibble]

IR, looked like just too much stuff.

Agreed!

[sumghai]

Chances are, any alternative re-interpretation of IR is going to end up being effectively the same as IR.

The key to moving joints in KSP is the ability to dynamically rebuild the relative position of all the parts connected to the joint in real-time, and so far, only IR has successfully implemented such a feature. No point in re-inventing the wheel when there's a popular and well-maintained add-on that already does the job.

What do you find "too hard", "too complex" or "too much stuff" about IR? The UI? The wide selection of parts? The joint types?

[Kibble]

What do you find "too hard", "too complex" or "too much stuff" about IR? The UI? The wide selection of parts? The joint types?

Yes, those things!

The key to moving joints in KSP is the ability to dynamically rebuild the relative position of all the parts connected to the joint in real-time, and so far, only IR has successfully implemented such a feature. No point in re-inventing the wheel when there's a popular and well-maintained add-on that already does the job.

The real problem, personally, is that IR just adds too much based on that feature. Spacecraft don't use winches and gantries and junk, most of the mechanical joints on real spacecraft are small and associated with like solar panels, and things that can be expressed as a single part. Extensible booms, however, are ubiquitous - and tethers have flown numerous experimental and operational missions, and are likely to fly many more. Hopefully Steven Canfield's and Kirk Sorenson's wonderfully practical (and surprisingly effective) xGRF concept will be recognized and flown!

Edited March 2, 2015 by Kibble
Now with extra optimism!

[ultrasquid]

OK, so you want something more like the DMagic Orbital Science Magnetometer, but one you can stick a thing on the extending end of it, science function being irrelevant.

I think the model is meant to simulate a lightweight scissor-lift linkage, but I'm pretty sure it's faked by using a partly transparent texture map.

[tater]

Chances are, any alternative re-interpretation of IR is going to end up being effectively the same as IR.

The key to moving joints in KSP is the ability to dynamically rebuild the relative position of all the parts connected to the joint in real-time, and so far, only IR has successfully implemented such a feature. No point in re-inventing the wheel when there's a popular and well-maintained add-on that already does the job.

What do you find "too hard", "too complex" or "too much stuff" about IR? The UI? The wide selection of parts? The joint types?

I don't want many of the parts, in short. If it were just IR alone, then I might not care, but more and more parts jest become cluttered, particularly if many I will never use. A previous build I had with a number of mods tended to crash after playing a while as the memory use climbed, basically I want the stuff I want, and not the rest

[sumghai]

What do you find "too hard", "too complex" or "too much stuff" about IR? The UI? The wide selection of parts? The joint types?

Yes, those things!

I don't want many of the parts, in short. If it were just IR alone, then I might not care, but more and more parts jest become cluttered, particularly if many I will never use. A previous build I had with a number of mods tended to crash after playing a while as the memory use climbed, basically I want the stuff I want, and not the rest

- The UI consists of two buttons: one opens up a dialog box to control individual/groups of actuators, the other one opens up an editor to configure actuator groups

- Of the parts available, most of them are just different-sized variations on a small selection of types (piston, turntable, hinge etc); with 0.90's stock VAB/SPH part filter icons, it's even easier to find the part you need

- There aren't very many joint/actuator types

The key to moving joints in KSP is the ability to dynamically rebuild the relative position of all the parts connected to the joint in real-time, and so far, only IR has successfully implemented such a feature. No point in re-inventing the wheel when there's a popular and well-maintained add-on that already does the job.

The real problem, personally, is that IR just adds too much based on that feature. Spacecraft don't use winches and gantries and junk, most of the mechanical joints on real spacecraft are small and associated with like solar panels, and things that can be expressed as a single part. Extensible booms, however, are ubiquitous - and tethers have flown numerous experimental and operational missions, and are likely to fly many more. Hopefully Steven Canfield's and Kirk Sorenson's wonderfully practical (and surprisingly effective) xGRF concept will be recognized and flown!

You misunderstand me. By "rebuilding", I'm not referring to winches and gantries - rather, it's about how the underlying plugin works.

In KSP, the parts of a vessel are defined using relative coordinates for location and rotation, which in the stock game can never ever change (barring rapid unplanned disassembly). So while a simple animated extendable boom might be very easy to make using the stock animation module, it won't actually push connected parts outwards (because as far as KSP is concerned, none of the other parts need to move).

IR basically looks at, say, a piston, and says "Ok, what other parts are connected to this piston? What are their current positions right now? If I move this piston by X amount in Y direction, I should change the position of part A and B so that they look like they're also moving with the piston". By constantly updating the relative positions of all connected parts, IR effectively "rebuilds" the vessel in real time.

The stock game has an undocumented moving joint PartModule, and there's a good reason it hasn't been made into an actual part right now: SQUAD hasn't figured out how to rebuild relative part positions properly just yet, resulting in situations where the connected parts float free from the joint in weird directions. OTOH, through years of iterative development, IR has solved this relative part re-positioning issue.

The other advantage of IR is that it handles a wide range of joint types, so that you only need one plugin for all your robotics needs. Contrast this with your proposal for a plugin that *only* handles extendable booms: one day you might decide you also want rotational joints - do you write a totally separate plugin to handle rotational joints (and therefore duplicate code unnecessarily), or do you add that feature to your existing extendable boom plugin, and thereby effectively "reinvent" IR?

So basically, if you hate IR and want someone to write a different plugin for an extendable boom that moves parts connected to it, the new plugin WILL end up having the same underlying code as IR.

Edited March 2, 2015 by sumghai

[Harry Rhodan]

I don't want many of the parts, in short.

Then why don't you simply delete the unwanted parts?

[sumghai]

I don't want many of the parts, in short.

Then why don't you simply delete the unwanted parts?

Pruning part packs is definitely a valid alternative.

[Kibble]

The other advantage of IR is that it handles a wide range of joint types, so that you only need one plugin for all your robotics needs. Contrast this with your proposal for a plugin that *only* handles extendable booms: one day you might decide you also want rotational joints - do you write a totally separate plugin to handle rotational joints (and therefore duplicate code unnecessarily), or do you add that feature to your existing extendable boom plugin, and thereby effectively "reinvent" IR?

So basically, if you hate IR and want someone to write a different plugin for an extendable boom that moves parts connected to it, the new plugin WILL end up having the same underlying code as IR.

Thanks for the explanation! I don't hate IR, and I don't mind (or even really understand) the underlying code - just there should be a version that has better parts.

Plus pruning parts really is a chore unless you know exactly what you're doing.

[sumghai]

Thanks for the explanation! I don't hate IR, and I don't mind (or even really understand) the underlying code - just there should be a version that has better parts.

Plus pruning parts really is a chore unless you know exactly what you're doing.

If by better parts, you mean better-looking parts, ZodiusInfuser is helping sirkut rework the part models - they're also using TweakScale, so that the same small selection of parts can be scaled up to different sizes.

If instead, you mean less complicated parts, you'll just have to figure out which parts to prune. It's as simple as:

- Going into the VAB/SPH and writing down the names of the parts you don't want

- Open your GameData and find the CFGs defining the parts

- Use Notepad++ to search for CFGs containing the names identified previously

- Deleting those CFGs so that those parts will never show up in-game

[Kibble]

If by better parts, you mean better-looking parts, ZodiusInfuser is helping sirkut rework the part models - they're also using TweakScale, so that the same small selection of parts can be scaled up to different sizes.

I mean better and better-looking, the parts included in IR are niche and numerous.

[sumghai]

I mean better and better-looking, the parts included in IR are niche and numerous.

Have you tried the IR rework parts? You can ignore everything else and use the telescoping pistons. Tweakscale allows you to reduce part list clutter too.

Failing that, you can make your own IR-powered robotics part, and delete all the original IR parts. You'll need to get comfortable with Blender and Unity, though.

Edited March 2, 2015 by sumghai

[tater]

One, I don't use tweakscale, so that's off the table. Two, I can certainly prune the parts, but I'm never really sure what I need to delete to be honest. Three, nothing looks like what I actually want, which is a deployable truss of some sort.

I should add that I never actually DLed IR until just now, and had no idea the part count on it was as low as it was. I had seen pictures of things made with it, and assumed there must be a million parts (many must have been scaled). Still, noting looks like what I want.

Edited March 2, 2015 by tater

[sumghai]

One, I don't use tweakscale, so that's off the table.

I guess that's just too bad.

Two, I can certainly prune the parts, but I'm never really sure what I need to delete to be honest.

As I said to Kibble:

you'll just have to figure out which parts to prune. It's as simple as:

- Going into the VAB/SPH and writing down the names of the parts you don't want

- Open your GameData and find the CFGs defining the parts

- Use Notepad++ to search for CFGs containing the names identified previously

- Deleting those CFGs so that those parts will never show up in-game

Three, nothing looks like what I actually want, which is a deployable truss of some sort.

http://www.sbir.nasa.gov/SBIR/successes/images/7-047pic.jpg

I should add that I never actually DLed IR until just now, and had no idea the part count on it was as low as it was. I had seen pictures of things made with it, and assumed there must be a million parts (many must have been scaled). Still, noting looks like what I want.

In which case, download IR just for the plugin, and make your own custom part in Blender / Unity.

[tater]

So you cannot merely delete the named cfg files themselves, but references to them in another file (notepad reference implies I cannot simply look for the part_name.cfg)?

Also, for such a truss/boom/whatever, I do not require it be reversible. I imagine assembling a spacecraft with NTRs well back on a set of trusses that are compact to start, but end up being 10s of meters long deployed.

Regarding tweakscale, it's just another mod added to the mix. I'd prefer to keep the mod count as low as possible. If IR had a truss, I might well decide it was worth it, but as it doesn't, I don't have any use for it.

Is the single, deployable part (like landing gear, shielded docking port, etc) more or less complex in terms of how the game deals with it than IR?

Edited March 2, 2015 by tater

[Kibble]

In which case, download IR just for the plugin, and make your own custom part in Blender / Unity.

I guess that's what I meant! I would like to use some of IR's code (the part that makes it work) and release a mod with different stuff.

[sumghai]

So you cannot merely delete the named cfg files themselves, but references to them in another file (notepad reference implies I cannot simply look for the part_name.cfg)?

Technically, just deleting the unwanted CFGs will work just fine. My instructions were in case the CFG files had non-trivial names.

Also, for such a truss/boom/whatever, I do not require it be reversible. I imagine assembling a spacecraft with NTRs well back on a set of trusses that are compact to start, but end up being 10s of meters long deployed.

It doesn't matter if the part is not reversible, because as long as you have a moving part that changes the position of another part, the IR vessel-rebuilding code is required.

Is the single, deployable part (like landing gear, shielded docking port, etc) more or less complex in terms of how the game deals with it than IR?

The landing gear, shielded docking ports and cargo bays are far less complex than IR, because they are just animations plus colliders. But conversely, they are unable to change the position of any other part attached to their moving ends.

I guess that's what I meant! I would like to use some of IR's code (the part that makes it work) and release a mod with different stuff.

Save yourself the grief of recompiling your own plugin, and just focus on making the custom part.

[tater]

OK, that makes sense. So the text editing is only in the case of a part name that is clear in the cfg description, but not the part name. Cool.

[Kibble]

Save yourself the grief of recompiling your own plugin, and just focus on making the custom part.

Oh okay. I would need help getting started though. Uh I'm not asking you though - its actually pretty surprising your engaging in discussion on my thread! Your stuff is legendary

[sumghai]

Oh okay. I would need help getting started though. Uh I'm not asking you though - its actually pretty surprising your engaging in discussion on my thread! Your stuff is legendary

List of resources and guides to modding in KSP: http://forum.kerbalspaceprogram.com/threads/94638-Mod-Development-Links-Compilation-START-HERE

How to make a custom IR-compatible part: http://forum.kerbalspaceprogram.com/threads/81568-Tutorial-How-to-make-robotic-parts-for-the-Infernal-Robotics-plugin

(I think AdjustableRail is what you're after)