Gravity Curve

[doug-hines]

So I am attemptign to bake out a gravity curve on a ball to use as reference for a character falling. I saw the technique on one of Alias' "Maya Techniques" vidoes (Hyper-Realistic Animation) but I am unable to reinstall the software for some weird reason, and I cannot for the life of me remember how to set the expression.

I was curious if anyone here could referesh my memory.

[joojaa]

don't you have a equation refrence/natural sciences table book in your shelf? Tip Get one they dont cost much you can probably get one free form any campus.

QUOTE(kurokawa @ 12/11/08, 09:16 PM) [snapback]296902[/snapback]
and I cannot for the life of me remember how to set the expression.

x=x0+v0t+0.5*gt^2

x= distance traveled
x0=starting distance
v0=original velocity
g=the force of gravitational pull 9.81m/s^2 on earth on the average at sea level
t=time

probably you can eliminate the 2 first terms for

yourobject.yourAttribute=0.5*9.81*time*time

If you have some residual speed you can do things like bounces etc.. it also by the way translates to vectors just replace single values with vectors with right directional magnitudes.

PS theres even a way without expressions just assign gravity one the ball and bake the sim!

[doug-hines]

pSphere1.ty = .5*9.81*time*time
Hrm, I'm getting a weird error: // Error: Line 1.34: Invalid use of Maya object time

[joojaa]

is that inside a expression? tie should be globally defined for expressions. But yes expressions houldnt give out thet error so your trying to pul it into a mel command of some kind?

Nut yes no problems works for me.

PS you amy want the 0.5 to be negative if you mean down to be in -y direction

[doug-hines]

Yeah I got it to work. I ended having to type it into the expression editor. I thought I could just type it into the channel box and it would work.. but it didn't

[joojaa]

QUOTE(kurokawa @ 03/09/09, 05:45 PM) [snapback]302624[/snapback]
I thought I could just type it into the channel box and it would work.. but it didn't

Well you could have typed = .5*9.81*time*time in the attribute editor. But no not channelbox.

But this si something I dont get, in maya i get this low level access to nearly ALL gui stuff in it. But when it comes to the challenbox no way. How much computational time would you guys expect me to waste if i typed asjkgh into the channelbox and passed that for my own parsing? You could implement so much cool stuff that would make you cry. Such as those pesky inches and feet.

I kindof get why you cant really adjust the what it shows. Itd be too slow but the typed stuff is after all limitted to the input speed of the user and no user truly reacts in a microsecond honestly, and you can do a lot fo pasring in a microsecond or 2.

Also maya really really needs plug (plug is the users half of a attribute by the way) aliases, not just named aliases but phycisal accesses to plugs that lie in other nodes. I mean it would solve nearly 50% of the problems we work a lot to get around. Se how hard would it be to present the same value in many nodes even if they aren't there and access them like they were. You could get rid of half of all stupid rigging issues thisway. Incidenttaly the first ting i mentioned could handle this altough not that elegantly.

PS: there's some underlying context magic you could do to do this haven't succeeded in wrapping my head around it yet tough. But im pretty sure it can be hacked even if i haven't seen anybody do it yet. Yes this si the sort of things i think about.

PPS: been reading old Steve Yegge blogs and Pratchett makes my head go overdrive. Probably flushes my logic barin and floods over to the emotion one thats REALLY good at processing volumes of stuff at far greater pace than the higher order forntal lobe can cope with.

[doug-hines]

Glad I'm not the only one that get's frustrated over Maya's limitations.