Drag on light objects? And also Drag vs Gravity

Unity Engine
1

Right now i’m doing some testing related to smashing apart walls of chunks held together with joints. I’m trying to mitigate a certain exploding factor.

When the wall is made of large, but extremely light chunks (something akin to polystyrene) firing a cannon at it causes physics to spazz out a bit, and the chunks are basically thrown so fast they practically teleport a good distance away.

As anyone who’s ever tried to throw a piece of polystyrene can tell you, this shouldn’t happen. no matter how hard it’s thrown, a large but light object doesn’t go very far before the air simply robs it of momentum and it drops.

I’m trying to fix this effect by adding drag, which should prevent them being launched too far. It’s not quite working as expected, they do still get launched quite a long distance, but their speed drops exponentially and they basically come to a stop pretty quickly.

The other problem is, they stop, literally. In mid air, almost. Increasing drag affects gravity too, so these chunks fall out of the air at absurdly slow speeds, which doesn’t make sense. Gravity still pulls objects downwards

I could do with some suggestions here on how to make large, non-dense objects feel right.

2

You’re on the right track, I would think…

A heavy projectile moving at high speed makes contact with a bunch of low-mass chunks, so when the energy is transferred, the chunks go pretty fast. In reality, the thing that makes foam slow down quickly is its low mass/flux ratio, or high drag, so…

I’m guessing that the solution probably lies in some intermediate values for mass and drag that you haven’t happened to try yet, unless you’ve really done this to death already.

EDIT: I played with it a bit on my own, I do see what you mean… Things get floaty at really low drag values. Maybe just smoothly clamping the velocity if over a certain threshold is the way to go here? Probably would have to similarly clamp angular velocity. Drag force usually varies with the square of velocity, but I wonder if it’s a direct variation in Unity?

How “big” are the chunks by the way? Maybe just increasing the mass will give a more realistic initial speed. If they would really be extremely light, then floating downward with high drag is realistic enough, isn’t it?