Jump to content
  • Advertisement
Sign in to follow this  
3DModelerMan

Unity Cost of multiple LUA states

This topic is 2569 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

I'm going to use SWIG and LUA for my game's scripting system, and I ran into a design barrier. I want my script system to work like Unity3D's, how the code outside functions is where variables go, and the update, fixedupdate, awake, etc functions are called at certain times by the application. The way I could think of to do this would be to have one LUA state per game object/actor/entity, would that take up too much memory? Are there any games that actually do that? Or is there a way to do it with one global LUA state object, and call multiple functions that all have the same name, but for different objects?
Thanks for any help.

Share this post


Link to post
Share on other sites
Advertisement
No, you do not want to have a Lua state for each individual whatever. That's just silly. Not because of the memory usage (Lua has a small footprint, but if you have a thousand states those are going to add up), but because it doesn't make sense. I'm unfamiliar with SWIG so I can't comment on its capabilities. I use Luabind with my project and it works great.

  • We have one global state
  • We have hundreds of C++ functions, classes, enums, and other objects bounded to Lua
  • We have functions that have the same name, but use a different signature (may be that they are either on a different class, or their parameter list/return values differ)
    I think that's pretty much the way you want to go. You want to have one state so you can share data, functions, etc. across all your different script files.

Share this post


Link to post
Share on other sites
Heh, I just went back through my code and discovered that is in fact not the way we did it. :P


We do have multiple Lua states. It looks like we create a new Lua state for each open file, and there's also a global Lua state. I think the way it works is we bind all of our code to the global state, and each new state we create is a thread that inherits from that state or something. I honestly can't remember; Its been years since I looked through this code. Its open source though, so if you want to take a look through it and see how we did things go ahead. The code is well-commented.

Web-browsable script engine source


There's also documentation at our wiki, although I think its more intended to explain how to use the engine and not how the internals of the engine function.

Script engine documentation

Share this post


Link to post
Share on other sites

Heh, I just went back through my code and discovered that is in fact not the way we did it. :P


We do have multiple Lua states. It looks like we create a new Lua state for each open file, and there's also a global Lua state. I think the way it works is we bind all of our code to the global state, and each new state we create is a thread that inherits from that state or something. I honestly can't remember; Its been years since I looked through this code. Its open source though, so if you want to take a look through it and see how we did things go ahead. The code is well-commented.

Web-browsable script engine source


There's also documentation at our wiki, although I think its more intended to explain how to use the engine and not how the internals of the engine function.

Script engine documentation





A LUA state for each file would probably work. But wouldn't that add up if there were a lot of scripts? The main problem I have is that if I have an object with a script that defines the "update" function, and another one that defines a different "update" function with the same parameters. Ineed to call the right update function for the attached object. If I had a script class that managed the LUA states for each file that would work well. How much memory does a single LUA state take on average? With all the libraries loaded?


Share this post


Link to post
Share on other sites

A LUA state for each file would probably work. But wouldn't that add up if there were a lot of scripts? The main problem I have is that if I have an object with a script that defines the "update" function, and another one that defines a different "update" function with the same parameters. Ineed to call the right update function for the attached object. If I had a script class that managed the LUA states for each file that would work well. How much memory does a single LUA state take on average? With all the libraries loaded?


Of course it would add up if there were a lot of scripts. The idea is to only open the scripts that you need and close them when you no longer need them. I'd estimate we have about 10 scripts open at a time in our game currently, and I'm sure we could handle many more. If you have two update functions for the same object with the same parameters, obviously you'll have to give the functions different names (UpdateA, UpdateB) and bind both to Lua. They'd have to be different names in C++ as well, since the function signatures would be identical.

I have no idea of the memory size that a Lua state takes. That would be something that you would have to measure yourself, perhaps with a memory profiler or making a simple stand-alone application that opens a Lua state and nothing more. Unless you're developing for an embedded system (phone, handheld console) I don't think that the majority of your memory is going to be consumed by Lua though.

The key is to make your Lua files represent a large amount of related information, rather than having a ton of small files that each represent a small piece of something. For example, a single Lua file for us represents one of the following.

- Initial attributes of all characters
- Attributes for a set of 100 enemies
- A single map
- All battle actions for a type of skill (attack, defend, etc)
- All status effects
- A tileset definition file (defines the properties of tiles for a composite image that are then used to create a map)


Sometimes you just have to dive in and start getting your hands dirty before any of this makes sense. Its difficult to plan everything first and then go do it when you don't have the experience, and usually you'll find things you forgot to take into account and you have to change your plan anyway. I'd recommend you work on implementing something that is roughly what you think that you want, see how it works, then make adjustments as needed when you find you need something to be changed.

Share this post


Link to post
Share on other sites

I'm going to use SWIG and LUA for my game's scripting system, and I ran into a design barrier. I want my script system to work like Unity3D's, how the code outside functions is where variables go, and the update, fixedupdate, awake, etc functions are called at certain times by the application. The way I could think of to do this would be to have one LUA state per game object/actor/entity, would that take up too much memory? Are there any games that actually do that? Or is there a way to do it with one global LUA state object, and call multiple functions that all have the same name, but for different objects?
Thanks for any help.


It sounds like you are after something more like this: (very roughly translated from my own code ...)


function update_entity( entity, delta_time )
...
end

function awake_entity( entity )
...
end

function create_entity( stats )
local new_entity = {}
new_entity.stats = stats
new_entity.on_update = update_entity
new_entity.on_awake = awake_entity
return new_entity
end

function update_boss( entity, delta_time )
...
end

function awake_boss( entity )
...
end

function create_boss( stats )
local new_boss= create_entity( stats )
new_boss.on_update = update_boss
new_boss.on_awake = awake_boss
return new_boss
end




-- called from application

function init_scene( level_description )
for i, entity_description in pairs( level_description.entities ) do
...
local entity_id = ...
local entity = create_entity( entity_description.stats )
entities[entity_id] = entity
end
...
end


function update_scene( delta_time )
for i, entity in pairs( entities ) do
entity.on_update( entity, delta_time )
end
end


function awake_entity( entity_id )
entities[entity_id].on_awake( entities[entity_id] )
end


It is perfectly fine to organise your scripts into separate files, but I think that you should only really start using multiple lua states when you have a good reason to; ie. to run them on separate threads, to separate scripting layers, etc. Suggest also checking out http://lua-users.org...impleLuaClasses (and the rest of the wiki ;)) for ideas on organising your game scripts.

Share this post


Link to post
Share on other sites
Sorry for the late response. I know of at least one working MMO which holds well over a hundred lua_states in memory at all times. It's workable. But as has been adequately noted above, this is not at all needed for a system where you just want to poll many individual NPCs periodically - you can do that with one state.

Share this post


Link to post
Share on other sites
Sign in to follow this  

  • Advertisement
  • Advertisement
  • Popular Tags

  • Similar Content

    • By D34DPOOL
      Edit Your Profile D34DPOOL 0 Threads 0 Updates 0 Messages Network Mod DB GameFront Sign Out Add jobEdit jobDeleteC# Programmer for a Unity FPS at Anywhere   Programmers located Anywhere.
      Posted by D34DPOOL on May 20th, 2018
      Hello, my name is Mason, and I've been working on a Quake style arena shooter about destroying boxes on and off for about a year now. I have a proof of concept with all of the basic features, but as an artist with little programming skill I've reached the end of my abilities as a programmer haha. I need someone to help fix bugs, optomize code, and to implent new features into the game. As a programmer you will have creative freedom to suggest new features and modes to add into the game if you choose to, I'm usually very open to suggestions :).
      What is required:
      Skill using C#
      Experience with Unity
      Experience using UNET (since it is a multiplayer game), or the effort and ability to learn it
      Compensation:
      Since the game currently has no funding, we can split whatever revenue the game makes in the future. However if you would perfer I can create 2D and/or 3D assets for whatever you need in return for your time and work.
      It's a very open and chill enviornment, where you'll have relative creative freedom. I hope you are interested in joining the team, and have a good day!
       
      To apply email me at mangemason@yahoo.com
    • By davejones
      Is there a way to automatically change the start position of an animation? I have a bunch of animations set up on 3D models in unity. The issue is that I need to move the 3D models, however when I do so the animation start positions are not updated and I have to do it manually.

      Changing the transform of key frames is time consuming with the amount of animations I have, so I was wondering if there was a way to do it automatically?
    • By MoreLion
      hey all! We are looking for members for our Unity horror game! 
      Here’s the story:
      After a deadly virus plunges the world into chaos killing 85% of the human population there are now what they call “zones” these zones are watched very closely by the surviving government, people are checked every day for the virus, even if you touch the spit or any human waste or fluids of the victim who is infected, you will die. But one day, people in the west zone start to go missing, 1 woman goes outside the walls to uncover the mystery, is there more to the virus than meets the eye?, That is where your story starts.
      This game is not a long development game, I have loads other game ideas,
      I will also allow you to have a bit of creative freedom if you wish to add or share a idea!
      And no, it’s not a zombie game lol I feel like zombie games are too generic, in this game you will encounter terrifying beasts!
      There is some concept art one of our concept artists have made
      If interested email liondude12@gmail.com
    • By Canadian Map Makers
      GOVERNOR is a modernized version of the highly popular series of “Caesar” games. Our small team has already developed maps, written specifications, acquired music and performed the historical research needed to create a good base for the programming part of the project.

      Our ultimate goal is to create a world class multi-level strategic city building game, but to start with we would like to create some of the simpler modules to demonstrate proof of concept and graphical elegance.

       

      We would like programmers and graphical artists to come onboard to (initially) create:

      A module where Province wide infrastructure can be built on an interactive 3D map of one of the ancient Roman Provinces.
      A module where city infrastructure can be built on a real 3D interactive landscape.
      For both parts, geographically and historically accurate base maps will be prepared by our team cartographer. Graphics development will be using Blender. The game engine will be Unity.

       

      More information, and examples of the work carried out so far can be found at http://playgovernor.com/ (most of the interesting content is under the Encyclopedia tab).

       

      This project represents a good opportunity for upcoming programmers and 3D modeling artists to develop something for their portfolios in a relatively short time span, working closely with one of Canada’s leading cartographers. There is also the possibility of being involved in this project to the point of a finished game and commercial success! Above all, this is a fun project to work on.

       

      Best regards,

      Steve Chapman (Canadian Map Makers)

       
    • By Scouting Ninja
      So I have hundreds of moving objects that need to check there speed. One of the reasons they need to check there speed is so they don't accelerate into oblivion, as more and more force is added to each object.
      At first I was just using the Unity vector3.magnitude. However this is actually very slow; when used hundreds of times.
      Next I tried the dot-product check:  vector3.dot(this.transform.foward, ShipBody.velocity) The performance boost was fantastic. However this only measures speed in the forward direction. Resulting in bouncing objects accelerating way past the allowed limit.
       
      I am hoping someone else knows a good way for me to check the speed with accuracy, that is fast on the CPU. Or just any magnitude calculations that I can test when I get home later.
       
      What if I used  vector3.dot(ShipBody.velocity.normalized, ShipBody.velocity)?
      How slow is it to normalize a vector, compared to asking it's magnitude?
    • By Ds ds
      Hi, my name is Andres, I'm a programmer with a technician degree and a Diploma in C#, looking for a project in Unity to start my career in game development. I don't do it for a paid but a recognition and start a portfolio, preferably a 2D game. Thanks for read, have a nice day. 
       
    • By Victor Rodriguez
      Hi there! Is the first time that I'm posting here so I'm sorry if I'm doing it wrong ha. 
      So here it comes, my doubt is, I'm doing a game with different levels, each of these levels in one different scene. Each scene contains to cameras that you can change pressing a button. Everything works fine. 
      The only problem is that I would like it to look a bit more professional, and I would like that if you finish the level with camera2, the next level start the same way. I've been thinking about using dontdestroyonloadon both cameras, but obviously this cameras need to be attached to the player to make the movement work, what do you recommend? Sorry If I've explained it in a messy way, and feel free to dm me for anything. Thanks in advance! 
    • By Ike aka Dk
      Hello everyone 
      I am a programmer from Baku.
      I need a 3D Modeller for my shooter project in unity.I have 2 years Unity exp.
      Project will paid when we finish the work 
      If you interested write me on email:
      mr.danilo911@gmail.com
    • By markoal
      Hi,
      I'm Unity developer from Croatia and I'm looking to work on the paid project in my spare time.
      I have 5+ years of experience in Unity and I'm familiar with almost anything, including all platforms (also Switch, PS4 and Xbox).
      Feel free to contact me.
    • By bartekm777
      Hello
      About me
      Lvl 28   Programmer (day job: non-gamedev-programmer, making games as a hobby for about 2 years) Some vector art experience - tried to make some assets on my own using vector software and scripts   Some design experience (designing my own games ) About game
      Turn-based fantasy rpg inspired by games like Heroes 3 (also WoG mod), NEO Scavenger, Battle Brothers I would like to create easy to use editor for creating custom scenarios (similar to the one from Heroes 3) World and story are clean slate, I did some drafts but I'm not good at it so it's possibly subject to change I decided to create graphics using vector software + scripts to make it faster (rpg's tend to have lots of assets), also it's more precise and easier to create tileable graphics (for example: rivers, paths) No sound/music work has been done yet Who do I look for?
      Definitely someone with 2d art skills  I would like to focus more on programming 2D animator (skletal animations are preferred) Additional programmer could make development faster Someone for creating sounds/music/both It's a hobby project, I work on it in my free time. In case the project make it to the finish line and get shipped  - I can offer rev-share  
      Below should be few screens of what I already did (about 2 months of work) - some graphics, editor prototype screenshot and game prototype screenshot




  • Advertisement
  • Popular Now

  • Forum Statistics

    • Total Topics
      631357
    • Total Posts
      2999527
×

Important Information

By using GameDev.net, you agree to our community Guidelines, Terms of Use, and Privacy Policy.

Participate in the game development conversation and more when you create an account on GameDev.net!

Sign me up!