Tutorial Physics/XML "XML" Arguments and Explanations

[Popotte]

For the moment, ball mass in the (FizX) .xml is 8000...

 

[JLou5641]

oups. i would like to say 8000
ball mass is less important, it only affect object strengh needed to kick the ball with flipper, kicker, bumper etc... It don't affect ball behavior on PF, or on Rubber hit, or friction

but 80 work also, you need to adjust all mass and strength of kicker, bumper etc...but you also have less accuracy..

 

[AnonTet]

For the sake of completion and because I seem to be bored with nothing better to do :D

"Gravity (or the acceleration due to gravity) is 9.81 meters per second squared, on the surface of Earth, because of the size of Earth and the distance we are on its surface from its center", hence the 9810 value in the XML. BTW, this value is assumed accurate enough for general calculations.

Physics engines use mass because it allows for accurate representation of different conditions. An example we all know: the same object, thus same mass, on the moon weights less than on Earth (remember Armstrong jumping around on that heavy suit? :D ) And we're back to gravity.

Or, in school physics: W = mg. Where 'W' is the weight of the object, 'm' is the mass of the object, and 'g' is the acceleration due to gravity (the above 9.81 m/s^2)

I do remember many colleagues mistaking mass for weight. There's also confusion between speed and velocity and of course, this list wouldn't be complete if I didn't mention elasticity which most people also fail to understand.

When I started here, I actually read physics papers and delve into the world of rubber (don't do it, it's black mad science even for tire manufacturers :D ). Then I did the same for materials properties, like friction and hardness. But it gave me a pretty good idea on more XML settings too at the time. Something that ended up being useful for understanding FP physics engine especially with JLOU's testing.

Paolo, you keep mentioning smoke. Your the only one (posting) that seems to remember that. I have to wonder why though, very few tables, if you consider the sheer amount of FP tables released, used his spot on settings. It's rhetorical, no need to answer.

BTW, most values in FP work better between 0 and 1. There are exceptions for a few cases to allow flexibility but in pinball don't go above 1 is rule of thumb in those cases. Others have hard coded limits if you put values above or below the limits, FP will default to the max/min limit.