Values in the real world?

May 14, 2009 at 4:14 PM

I have been trying to enter values for gravity to be realistic as much possiple, but my qustion here if I want the gravity to be like in real world , and free falling acceleration (9.8 m/s2),

and other values like velocity that I get, what its value in the real world, and springs damber and constant, etc ......................

can any one help me

and I have a small question what is the difference between Linear and Quadratic drag coef?

May 15, 2009 at 8:56 AM
Edited May 15, 2009 at 8:58 AM

i don't know much about the internals of Farseer but all formulas should be independent of the units you use. however i somewhere read that Box2D once converted to a "full kilogramm-meter-second system".

keep in mind though that in games you seldom want realistic values. almost everything in games is fake. just tweak it until it "feels right". realistic values should just be a starting point.

linear and quadric coefficent are always dependent to something (velocity i think). the faster the body moves, the more drag you get. quadric drag just becomes WAY more higher with higher velocities,... in a quadric way so to say :)

@genbox (or any other physics guru): do you have a good source about how to backward calculate a maximum velocity and acceleration of a body given force, mass, friction, drag and (i think you need) update frequency?

May 15, 2009 at 2:13 PM

i don't know what units farseer is in (if any in particular).

however i would think it is more likely related to pixels than to meters (i am just guessing though)

May 15, 2009 at 4:56 PM

I used 980 as a gravity value, and it looks real enough