@Maximum_ADHD @Polymorphic This would be moreso for parts not applicable as regular physics objects, like if you wanted to attach a non-collidable light shaft to an unanchored model but you don’t want its required density to affect the rest of the model, knowing light is massless to begin with.
Numerous times I’ve come across issues where I can’t negate mass from purely-aesthetic parts. As poly and clone have mentioned though, giving them a mass of 0 isn’t physically correct and it’d be a pain to account for this in the physics engine. Instead of allowing density to be 0, here is an alternative solution:
###Ability to make objects not affected by physics
Parts not affected by physics would remain in place and wouldn’t collide with anything else or affect their physics. However, they could still be jointed to an a part, following it like normal jointed parts, while not affecting Part0’s physics, collisions, or CoM. This would only affect physics and raycasts/etc would still hit these parts.
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Normal physics aside I seriously need the minimum 0 for things that most likely aren’t even going to be Collidable, I just need the part but not its mass messing up the central mass of the rest of the model. Guys, this isn’t just about how parts will react by themselves if they don’t have mass.
For clarification, for anyone who needs density=0 parts, do you need them to be affected by physics (collision, gravity, changing CoM, etc)? If so, why?
- Don’t need physics
- Need physics
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would be an elegant solution to the whole “we want to use meshparts for accessories but they’re affecting swimming physics” thing.
Density=0 would make the character weightless though – character weight issues would be alleviated by setting their density to defaultPackageDensity/currentPackageDensity. Rather than for technical reasons though, I think package physics issues are more due to ROBLOX wanting them (unfortunately) to be physically accurate, which causes all sorts of problems for gameplay.
What you have proposed is essentially a part that is rendered and can be attached to a body with no physics being applied to it. Density would allow you to do this but it seems like the wrong solution to your problem. Some sort of render-only container already sounds like a better alternative.
I have a few use cases. I may want projectiles such as lasers which do not feel the force of gravity, but bounce off of walls etc. I may want a platform in the air that is static until the user stands on it, the platform should begin to naturally fall towards the ground.
In my opinion, there are a lot of use cases for this since essentially it’s what a lot of us are doing when we are using bodyforce.
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Fun fact: It is actually possible to set a part’s density to zero if you set it’s Material to Air.
If the part isn’t attached to something, it will instantly disappear.
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workspace.Player1.BiggerHead.Handle.Material=‘Air’
workspace.Player1.BiggerHead.Handle:GetMass()
this prints 0.01… if its customphysicalproperties is checked true.
this prints 0 otherwise. oh my god
can this extend to a max size part? 2048 cubed’s mass is 6012954112, while its 0.01 density mass is 85899344
Edit: I just tested the physics, and yup, when you switch back and forth, it switches physics between a very heavy object at minimum custom density vs a 0-weight object at no custom physics & Air material
I think all hats should be set to Air material in the catalog - or rather, when they load in your character, they should load as Air material. And you can’t drop them anymore so it shouldn’t be an issue
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It does? I welded a <500,500,500> part made of Air to my character and it’s treating it as if it weighs a ton.
Repro.rbxl (12.2 KB)
I was standing on a 2048 cubed brick that was welded to a 10 cubed brick that had a bodyposition in it. The 2048 Air brick would flip out and rotate if I jumped on it, until I turned on its CustomPhysicalProperties which made its density 0.01, which made it extremely heavy (and I had to crank up the bodyposition to insanely high numbers after a few attempts) and it wouldn’t flip out
I can confirm similar behavior – I welded 500x500x500 brick to a small part being held up by a BodyPosition with a low amount of force. When the large part was any material other than Air, the parts fell. When it was air, they stayed in the air. The issue seen in the file I attached in my previous post may be related to how the character handles physics.
Upon further testing, it appears the character is just wonky with Air parts (which is unsurprising since Air was never meant to be used as a part material). Just welding 10 Air parts flings me off into oblivion or straight up kills me. The main benefit of these would be with characters, but I wouldn’t recommend using them – too unpredictable.
File I used: Repro.rbxl (12.2 KB)
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An object with no density would have no inertia, meaning any force that touched it would immediately launch it at an infinite velocity.
Only in a vacuum, think feather. air-friction could still technically apply to a zero-density object.
An object with zero mass couldn’t even exist in air anyway; a microscopic pressure difference would send it moving at infinite velocity.
Wouldn’t it just compress itself into a dot, if you’re counting for pressure? I was assuming that some of the rules would at least have to be in place, for it to function as something to theorize about.
If you’re talking about if it has a low pressure zone above it, and a high one below it, no, it would not shoot away at infinite velocity, it will just move to the place where the pressure equalized, sub the amount of air-friction the surface had. Stuff would make excellent plane wings.
TL;DR none of us are actually scientists yet we are all debating theoretical massless objects and their physical behavior, all I want is for Roblox to remove the Density minimum so I can create Part objects not intended to be physically interacted.
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Yes, but it is an interesting concept to have a massless object be used in a physics based game. I could see some rather interesting gameplay from this.
And wouldn’t a massless object partially be able to phase through materials? (until friction+magnetism got to it?)
There’s also the problem of low density parts affecting water buoyancy. Sometimes we use large hitboxes to approximate complex objects with low actual volumes. TrussParts are a good example of this:
This is what we’re approximating, which has a significantly lower actual volume:
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