c# - Farseer physics mass/weight issue -

i have created platformer game using farseer physics player , objects etc having problem mass on objects.

the player composed wheel , torso connected joint , works when not setting mass on object. not using mass creates unstable simulation because when changing texture on object, mass increase or decrease strangely. when assigning correct mass , density nothing works supposed , don't know why. increase force , such correspond new weight on stuff when moving player slides , forth , kind of bounce sideways when stopping. , when picking object hacks on screen.

so know solution cause i'm stuck?

the thing have found far mass of body in farseer physics calculated density of fixtures. hence weight increase/decrease when changing texture. can't work when manually assigning weight.

taken box2d manual:

the fixture density used compute mass properties of parent body. density can 0 or positive. should use similar densities fixtures. improve stacking stability.

the mass of body not adjusted when set density. must call resetmassdata occur.

fixture->setdensity(5.0f);     body->resetmassdata(); 

you may need reset mass data in order work properly.