applyTorque Tutorial

[SpectreCat]

Great Tutoiral

Only have one small thing I didnt like:



Yellow + White = BAD

[Fizyk]

Thanks Now I know how to use it, but not why the hell it works like this (wtf is cross)

That is a thing for a whole another tutorial I actually thought of making a tutorial on basic maths and physics to help people understand what they actually do, I might make one in the future.
About cross, for now try this: [ame=http://en.wikipedia.org/wiki/Cross_product]Cross product - Wikipedia, the free encyclopedia[/ame]

In my opinion, a reference to wheels wouldn't hurt. It personally helps when I visualize torque as it is for wheels on cars, that they sit on an axis which spins in either direction.

Hmm, maybe you are right. I didn't think of wheels when making this tutorial.

Great Tutoiral

Only have one small thing I didnt like:

[ image ]

Yellow + White = BAD

Oh right, the arrow is visible quite clearly and I didn't notice it might be hard to read the text. I might change that.

Also, thanks for your positive feedback

[Tayg0]

Okay, I get how cross works now, and i see how that could be used as an axis, but I don't get how you can use that to control the torque,


Edit:
Okay nevermind I think i get it now,but I still don't get why you used vec(1,0,0) instead of E:forward()

[Jimlad]

I have a lot of questions about the logic behind adding applyTorque, which might suggest why it isn't being used so much... but for now, is it me or does it seem to apply double the amount of force to props as applyAngForce? In the very least it should be consistent with units of torque.

[nescalona]

You could test that by combining a torque vector (say, (1,0,0)) with the principal moments of inertia - your no-gravity'd prop should accelerate by one radian per second per tick.

entity():applyTorque(vec(entity():inertia():x(),0, 0)) should do it. Run that once and the prop should get an angular speed of 1 rad/s. Of course, source handles rotation in a really absurd way so acceleration bears only a distant relationship to velocity (whether angular or linear). It should be approximately correct, though.

@tayg0: because applyTorque takes an intrinsic vector (one measured according to local axes), not an extrinsic one (one measured according to world axes). In this, it is unlike applyForce.

[Fizyk]

I have a lot of questions about the logic behind adding applyTorque, which might suggest why it isn't being used so much... but for now, is it me or does it seem to apply double the amount of force to props as applyAngForce? In the very least it should be consistent with units of torque.

Oh yeah, you're right, it really does apply 2 times more force. Can someone fix that? Just change dir and dir*-1 into dir*0.5 and dir*-0.5
in calls to ApplyForceOffset.

[Tayg0]

@tayg0: because applyTorque takes an intrinsic vector (one measured according to local axes), not an extrinsic one (one measured according to world axes). In this, it is unlike applyForce.

Ohhh, so 1,0,0 would always be forward, the axis changes along with prop rotation right?.

[nescalona]

You got it. To convert from an intrinsic vector (relative to E) to an extrinsic one, do this:
matrix(E) * V
To convert from an extrinsic vector to an intrinsic one (relative to E), do this:
transpose(matrix(E)) * V

Example:
matrix(E) * vec(1,0,0) == E:forward()
transpose(matrix(E)) * E:forward() == vec(1,0,0)

[Tayg0]

Oh wow, thanks. I get it now. ^^

[-HP-]

That is a thing for a whole another tutorial I actually thought of making a tutorial on basic maths and physics to help people understand what they actually do, I might make one in the future.
About cross, for now try this: Cross product - Wikipedia, the free encyclopedia


Hmm, maybe you are right. I didn't think of wheels when making this tutorial.


Oh right, the arrow is visible quite clearly and I didn't notice it might be hard to read the text. I might change that.

Also, thanks for your positive feedback

Look what I found
Gah, stupid embedder
[ame="http://www.youtube.com/watch?v=zA0fvwtvgvA#"]YouTube - Cross product 1[/ame]
[ame="http://www.youtube.com/watch?v=o_puKe_lTKk#"]YouTube - Cross Product 2[/ame]
[ame="http://www.youtube.com/watch?v=s38l6nmTrvM#"]YouTube - Cross Product and Torque[/ame]

Not sure if they relate to this though, I couldn't be bothered to watch them through