Tech Demo: Water, Buoyancy and Ropes

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Hack Week coverage continues with a unified tech demo by Dan Ignatoff, Erik Cassel and Tim Loduha showing water, buoyancy and ropes working together.

Water and Buoyancy

Dan and Erik teamed up on the water and buoyancy simulation shown in the video. Dan has been working with many types of water simulation, including grid-based and particle based methods. We are showing a grid-based method here, but Dan has also mocked up a Smoothed Particle Hydrodynamics (SPH) model. We have not finalized the method we will use or ship date. In the demo you can see wedging at the lake/shore interface, which we will work out prior to shipping.

Erik Cassel has created a buoyancy enhancement to the physics engine that interacts with Dan’s water simulator. Erik is modelling both density and viscosity in the simulation.  He is keying object density off material, so that less dense objects (wood, plastic) float, while denser objects (metal, rock) sink. The equations of motion and collision detection methods governing buoyancy are very similar to those used for rigid body motion in ROBLOX, so the integration was relatively straightforward.

The demo does not include swim and wade states for characters (in development), so in Erik’s demo his character just walks along the bottom of the lake.

Tim Loduha has been improving our rigid body physics engine and gives a peek at more mechanical parts with the rope bridge. As the bridge falls into the water you get to see water, buoyancy and ropes all working together in the same physics simulation. This is a tech demo from hack week at ROBLOX, so right now we do not have specific ship dates.

153 thoughts on “Tech Demo: Water, Buoyancy and Ropes”

    • This doesnt even look like minecraft -.- and roblox isn’t copying them so stop accusing roblox for copying minecraft!

  12. Configure it so that a certain amount on studs you go inside to the water.
    Like if you’re 100 studs in the sky or something and you jump off, you wont just go like, WHEEEW, plop, and not sink to the bottom and come back up.
    Make it so that Its REALLY buoyancy. New material, Carbon Fibre. Thank you for your time.

  13. Bless you for the material, and the website certainly looks terrific. Just what word press theme are you using?

  15. When will this come out? I can’t wait!!! But what would happen if u shoot the water with the rocket, would the water turn into particals and fly up into the air?

  17. Maybe, a primitve particle/voxel hybrid system could be used to make relatively chunky particle simulation for waterfalls or whatever your little hearts desire. Another thing to minimize lag with particle fluid would be “baking” any water that isn’t going to change position, or is unreachable to players, so that it already knows the transformations and stuff it has to undergo (yep, I use blender).

  18. The Water should Fill Up spaces. Would we be Able to Create Spheres with Landmine Scripts that Float Around ?? I would love to make Water Mines. Anyway I think it should be Particle-Based and not Grid-Based.

  19. I love the new things the creators are making, it makes Roblox feel so real. What will they come up with next? The skys the limit, next thing you know they’re making dragons that breath ice cream. That the dream. :3

  21. Make it take the form of its suroundings like real water.
    Change the amount that it stick and breaks apart and look so you can make (for example) oil or elmers glue. Please put my ideas into consiteration.

    Thank you david for another amazing demo.

  22. Nice job, but I agree with Skatertater, the particle based fluids method, and it’ll be better

  23. I don’t like the grid based method. Go with the particle and maybe I’ll be interested in ROBLOX fluids…

  24. When this comes out, they should make it so when your generating terrain you could choose to generate it as several small islands.

  28. Use the particle method! I hope rope has a min and a max setting to it so i can make a grappling hook.

  32. Really epic, When it comes out someone could make a titanic that really SINKS down and now just falls down. plus if it floats it can move around and hit the iceberg and every time it could be different!

    • Don’t compare ROBLOX to Minecraft. Minecraft is an Indie Sandbox game, where the users create almost all of the additional features in the form of mods. ROBLOX however, all of the actual features are created by the development team and the users use scripts and creativity to make creative games.

      • Mitzi I can answer this bceuase my family lives down there! You are outside of my color planting schedule by about a month. The trick is, Las Vegas gets so hot in the summer, but you can grow almost all winter long. My book is really for a spring-summer-fall planting schedule. The dates I offer might work for you and others who live in warmer climates, but really have a spring-summer and a fall-winter season. I am very aware of your needs, and it’s on my list of things to research and write about. But honestly, I can’t speak from experience, only from my research. I encourage you to contact your local extension service (www.extension.org) for a recommended planting schedule.

  34. I think this is an Amazing Idea, With most Boats, there is usually a Script called “Hover” And the “Hover”‘s value can be changed to make it look like it’s floating. And It took me, like, months to Figure that out. Lol. The new Update will sure have my vote! ;D Keep up the Good work!!

  37. The grid-based water is cool, and would work really well for large bodies of water, but I really hope we will also be able to play with the particle water, which to what i understand, would be able to move like a river, ripple like tides, and flow like in pipes. :D

  38. Oh my god, I never tought this was possible when I was here in 2009, now I see the you go to the infinite and beyond!

  43. This feature looks very promising. If it hasn’t been suggested yet, aim towards a system where you can make water flow downhill!

  44. If we were to make pirate ships could there be a tool to show what path it has to go? That would be really good for traveling.

  45. Next step – Swimming
    Second step – Clear quality water texture

    Third Step – THUMBS UP!

  46. Cool physics, but aesthetically speaking it looks terrible, because, like terrain, it doesn’t really fit in with what roblox originally looked like.

  47. NOTE: I’m talking about all of the different things they’re working on, not just the water.
    These are tools that could let all players (not just super awesome scripters) be able to make awesome places. I’m pretty sure this might increase the quality of games coming from players who don’t spend as much time on building and scripting their games (great for group leaders, and I mean all of the stuff you’re doing).

  48. This would be good for games like pool tycoon and build-a-boat and sail it to the end.

  49. This doesn’t look ANYTHING like what I saw in the textures folder………. I saw a transparent texture with bubbles. Please make it like REAL water rather than Minecraft water.

  50. This looks alright, I just don’t like the fact that there concentrating on Voxels or whatever so much. Voxels is nice for landscapes but for detailed building or mini building this renders completely useless.

  51. To be honest, it looks a lot like Minecraft. I hope that Minecraft is okay with this stuff going on, but I guess that it’s just a step within an entire lifetime of development.

  55. It sounds really good to me, our fellow robloxians, for as long as I can remember, sence 08′ we have been faking all of these physics, it sounds like a great idea to me! But, I have to say, the spreading of the water was poor, thats probably needs to be next on your list along with swimming. Also, the motioning of the water doesn’t look right to me, maybe tweek that a little bit too. Over all; Very good idea, I can’t wait for the release :)

  56. Looks pretty good so far,the buoyancy looks like it’s almost finished,though the water grahics are ok,im sure you can make it look alot better.
    Im hoping there’s also a swimming engine in roblox that lets you dive and swim and also how long you can stay underwater before dieing (Which can be changed in roblox sutdio settings) but also have current of water to
    When you look underwater i hope the screen or display becomes slighty blue.
    I also wish to see that you can change colour of water,murkness and how many things are found in it,e.g fish etc.

  57. It seems like it would help a lot for when making like an RPG or something of that sort, but just one question, how will you make the suspension bridge? Would you be able to build it for Example a Private Server or would you have to build it in RBLX Studio?

  59. Brilliant! The water doesn’t collide with the Corner mesh though.
    Maybe Tides could be added later on. :)

  62. So this would allow players to make transparent orbs that float upwards now in place of scripted bubbles? Nice.

  65. Does the water take over the pit or does it HAVE to come in a shape like terrain? It would be cool if it took over a pit instead of finding the perfect size to make it look like a flooded pit..