java - Bx2D body Sprite synch -

seeing how box2d bodies cannot resized, have problem bodies , animated sprites.

here's situation have no doubt not unique: sprite's dimensions change during different motions attacking, walking, jumping. seeing how use box2d body collision detection can cause quite problem. far thought of 3 ways solve issue.

1- not use box2d bodies collision detection , use them object's physical behavior

2- delete , recreate body before each render. or on animation change.

3- trying recheck collision on bodies see if collides sprite itself. act.

and here's problem have each of these solutions.

1- way makes using box2d whole seem rather absurd, i'll using not one, 2 world logic , trying keep them in sync. seems big headache.

2- doesn't optimized, doubt can make objects pop in , out of existence in physics world without side effects.

3- i'm not sure how or if can done, option 1 require more advice on. cause difficulties in long run, or cause conflicts in physics.

please let me know if there efficient way solve , or if of above solutions worth working on.

my thanks

edit: more of general question since still don't have proper graphics game i'm writing, here's practice material:

walking waiting (standing) attacking

a body can have multiple fixtures, can add fixtures each state body. if make them 0 density should not affect physics behavior of body. keep in mind though, @ least 1 fixture on body should non-zero density - make 1 fixture act main fixture, has density give body mass.

if need detect when these fixtures touching something, make them sensor fixtures, , use contact listener keep track of other things touching. contact listener give callbacks of fixtures regardless of state character in, , each state keep list of things fixtures state touching.

if need fixtures have physical interaction when state active, above in begincontact contact->setenabled(false) if contact fixture not in active state.