Negative weight physboxes?

[FictiousWill]

I'm playing with my airship model that I made this afternoon and I'm tired of attaching tens of balloons to it to get it to fly, so I made a capsule shaped brush object and made it a physbox.

It will function as the balloon for the airship, so I gave it a negative mass in hammer. However when I run the game it falls to earth!

Is there any way to create negative mass physboxes?

 

[Milkman]

Well, in real life it is impossible to have negative weight, since weight is mass x gravity, so unless the gravity is negative, I can't see how it would ever work. Then again it is a game and not real life so its beyond me how to solve this problem. :/

 

[FictiousWill]

Milkman......... it's a physics engine variable. A number.

Anyway, the only option I can find is the mass multiplier, which I set at various negative values. When I run the map though, the object still has mass based on it's volume. (which is, of course, positive.)

 

[Milkman]

I have tried running gavity at negative numbers in HL2 but everything acts normal until it jumps.

Sorry for thinking too hard.

 

[Exavior]

Try this. Attach a physics thruster to your "balloon" and have the thrust directed upward. You may also need a physics "keep upright" element to make sure your "balloon" does not tilt too much.

You would have to tweak the thruster settings a lot to get the balance right, but it should work. Also, look at the check boxes under the thruster properties. Some of them may be required to get the thruster to behave properly.

You may also want to use multiple thrusters, to help balance the object.

 

[FictiousWill]

The object requires upwards of 200 9-level thrusters to get airborne. A negative mass value would be so much easier. Seems kindof counter-intuitive to use loads of thrusters and balloons.... to lift my large balloon.

 

[FictiousWill]

Ooooooh you meant thruster entities! I see - I'm trying this now. Apologies for misunderstanding you.

 

[FictiousWill]

YES! I have it working - I was thrown for a very long time because the phys_thruster thrusts away from the angle you specify in hammer. Many thanks, Exavior. A bit of tweaking and it's all done!

 

[Exavior]

Congrats. I'm glad it worked.

There is a lot of fun to be had with physics thrusters. I can't wait to play when them more. Sadly my curent project is too "practical" to have use for them.

 

[Secret_Machine]

Could we have some shots of this Fictious?

 

[Mr Neutron]

here's another possibility:

make a trigger_vphysics_motion around the balloon (make sure to parent it to the balloon too; you'll also want to filter for just the balloon, just in case another object comes into contact with the trigger). I don't know if you could set a non-zero value for the gravity, but I think you can set a negative value.

Also, I think a gravity manipulating trigger is permanant upon that object until the object touches another gravity manipulating trigger: it's like changing a property of the object. So I think you can just kill the trigger volume after it fires once; you don't have to leave it running to remain in constant contact with the object, which induces a (probably tiny) performance hit; this would be a neater solution than parenting it though, and you wouldn't have to use a filter.

Another advantage, assuming gravity can be negative, is that the floating object, once it hits the ceiling, would go to sleep, thus saving some bandwidth.