2 Weighty Questions: 2 of Units and 1 of Scales

LarryG on 26/12/2010 at 21:05

OK I lied. One of the questions is about mass. But close enough.

Question the First - a technical query
At Physics > Model > Attributes there is a list interesting physical characteristics, among which are today's subjects: Gravity % and mass. Gravity % I take to mean the percent of a standard unit of gravitational acceleration, gn, defined to be about 32.174 feet per second per second. (I believe that in the Thief Universe, the standard unit of distance is as close to 1 foot as makes no difference, and the standard unit of time is a millisecond, so I think this is a safe assumption.) But what of the next parameter, Mass?

Some, those with the most catholic of knowledge, might argue it refers to the number of times per week that the object attends religious services.
:joke:

But all kidding aside, what unts should be assumed for mass? In SI, the base unit of mass is the kilogram (kg). In the English system, the pound (lb) is the unit. I doubt that the atomic mass unit (u) is intended, though with time measured in milliseconds, I suppose it would not be entirely inconsistent.

Consider Garrett. (http://www.ttlg.com/forums/showthread.php?t=76151) According to Fidcal, Garrett is 6 units (ft) tall. And according to the standard DromEd settings for Garrett's avatar, he masses 150 somethings. (http://www.healthchecksystems.com/heightweightchart.htm#frame) Standard height and weight charts indicate that a fit 6 foot tall man with a "Small" frame should weigh between 149-160 lbs, with a "Medium" frame 157-170 lbs is normal, and a "Large" framed 6 foot man would weigh between 164-188 lbs. Garrett would have to be very small framed for his mass units to equal the pound value for an adult man (Garrett has 100% gravity).

Now I think of Garrett as medium framed, slim but not thin, well muscled but not husky. Is that reasonable? Fidcal says the minimum doorway width that he can fit through is 2.5 units. That would make Garrett's shoulders pretty wide. His avatar's shoulder limit planes are 1.5 feet apart in Anim8or. So his biceps would have to be 6 inches wide each. That's extremely muscled. So how fit is Garrett?

Consider Garrett's vertical jump of 2.5 units (ft) reported by Fidcal. The average vertical jump in the NBA is reported to be 28 inches. That's for guys who average 6' 7" tall. Garrett's 30 inch vertical would put him better than more than half of the NBA players (but nowhere near Michael Jordan's reported 48" vertical jump, let alone Kadour Ziani's nearly 61" leaping ability). Clearly he is an athlete of the first water, consistent with his shoulder width.

So all this implies to me that 150 mass units should somehow equate to between 157 and 170 lbs, maybe between 164-188. Assuming the middle value of 172.5 lbs, this implies that 1 Thief mass unit = 172.5 / 150 = 1.15 lbs.(~ 0.56 kg). So, for each lb you intend an object to weigh at 100% gravity, you should use a mass of about 0.8696. does this seem right to you too?

Question the Second - a DromEd technique query
Is it possible to detect the weight of an object placed on a pressure plate? TrigPPlate does not provide a way, I don't think. And using NVRelayTrap looking for "PressurePlateInactive" and "PressurePlateActive" doesn'e seem any more productive. I really would like to control a rotate tweq indicating the weight of the objects placed on the pressure plate (Physics > Misc > Pressure Plate). Suggestions?

R Soul on 26/12/2010 at 23:34

Quote Posted by LarryG

I suppose it would not be entirely inconsistent.

Don't expect consistency. Remember that angles are sometimes in degrees, sometimes radians and for things like mesh attach it's a proportion of 65535. Anticlockwise from south.

Question the Second - a DromEd technique query
Is it possible to detect the weight of an object placed on a pressure plate?

Weight? Or mass?

I think the best way is to add a source the object and give the pressure plate a receptron with a narrow range of intensities.

LarryG on 27/12/2010 at 03:08

Quote Posted by R Soul

Weight? Or mass?

Is it the mass value or the mass value times the gravity percentage that the pressure plate responds to? The value is labeled "Activation weight" so I assume that means the mass times gravity percentage is what is used.

Quote Posted by R Soul

I think the best way is to add a source the object and give the pressure plate a receptron with a narrow range of intensities.

The idea is to allow the player to "weigh" anything that can be carried to the "scales" so I would rather not have to add a custom WeightStim source (propagation: contact) to every transportable object. If I have to ... but how does the pressure plate "know" if there is the trigger amount on it in order to send the "PressurePlateActive" message? Is that value directly accessible somehow? Then is there a way to rotate a tweq joint proportionate to the stimulus value? I've looked for an explanation of Act/React > Receptrons > Behavior > Effect > Tweq Control but haven't found any. It seems you can specify which tweq (Scale, Rotate, Joints, etc.). You can specify various actions (Forward, Reverse, Continue, Halt, etc.), And you can set the MiscC (its called XtraBits, but has the same setting choices as MiscC: On, Reverse, ReSynch, GoEdge, and LapOne). But I don't see any way to change the high value in the rate-high-low parameters, as would be necessary to get a joint to rotate proportionate to a stim strength. Is there something I'm missing about that? Maybe a property set approach would work?

Quote Posted by Nameless Voice

I think you're taking things too seriously.

Likely you're right. I was just going to ask if there was a commonly accepted interpretation of the mass parameter, but then I thought I should do some homework first. It got out of hand. :cheeky:

R Soul on 27/12/2010 at 15:51

Quote Posted by LarryG

The idea is to allow the player to "weigh" anything that can be carried to the "scales"

To be blunt, that sounds very boring. For one object at a time it is certainly possible. The joints property is called cfgtweqjoints, which can be changed via a receptron for a contact stim. There should probably be a short delay between receiving the stim and activating the joint. You wouldn't need a pressure plate; any solid object would suffice.

But that would be for one just one mass. The greater the range and the more precise the scale, the more fussy it will be. Imagine a scale of 0 - 50 pounds, accurate to the nearest pound. That's 50 'agent' objects. Even with a very imprecise scale, say accurate to the nearest 10 pounds, you'd still have to add the right source to every movable object. And if this is for your keeper mission, why would the keepers have a scale so imprecise? The keepers are supposed to be awesome in a very understated way.

And then there's the issue of several objects being placed on the scale. :sweat:

LarryG on 27/12/2010 at 17:15

Exactly. That was the best I could envision on my own, hence the posting, hoping that someone knew something useful regarding this that I didn't. Ideally I would have liked a balance beam scale setup, but could have made my idea work with the traveling platform of a platform spring scale, hence the pressure plate thought. Detection of the weights of whatever is place on top of it seemed to be built in, just not reported. Then there was the problem of getting a joint to travel proportionate to a supplied value. Those were the two intractables I was hoping that someone knew reasonable approaches to solve. As you point out, if I wanted to weigh arbitrary combinations of objects I would need an unreasonable number of fnords for property sets if I wanted to try that method. :(