Problem with physics

[Gamerazor]

Hello

Im doing the game like arkanoid. The problem is when I try to move the bar with physics. When the bar has collided with the wall it lose the path and don't move straight to left to right. When I also try with moveWithCollisions() it works bad when the bar collide with the ball. How can I resolve this?

[GameMonetize]

you can simply add an invisible wall behind the bar to keep it in line

[Gamerazor]

but, won't the bar bounce forward?

[GameMonetize]

crap! that's right

 

The problem is that this is a physics engine and is goal is to simulate physics  

[Gamerazor]

then how can i resolve this problem?

because the ball needs the physics engine and the bar needs collide with the ball. 

[Gamerazor]

ok the problem is resolved with:

 

barra = Balltingo.getMeshByID("Bar")
body = barra.setPhysicsState(BABYLON.PhysicsEngine.BoxImpostor,{mass: 1000, friction: 0.00001, restitution:0.00001})

 

move = (body,barra) ->
 s= 2
 if body.moveLeft
  barra.applyImpulse(new BABYLON.Vector3(0,0,-s),barra.position)
 else if body.moveRight
  barra.applyImpulse(new BABYLON.Vector3(0,0,s),barra.position)
 body.body.linearVelocity.scaleEqual(0.92)
 body.body.angularVelocity.scaleEqual(0)
 return

 

#this is coffescript

[Wingnut]

Hi

 

Ahh, you made the bar very heavy... good idea!

 

You may still see the bar move a small amount every time the ball hits it.

 

Do you know that physics engines sometimes zero-out rotations on a mesh... when you do mesh.setPhysicsState?  (It is because they switch to quaternion-based rotation, I believe). 

 

Now, think about doing this (pseudo code) inside a render loop/animation loop:

 

bar.clearPhysicsState()

bar.fixMyBarZpos()  // reset bar z-position in case the ball has been "pounding it downward"

bar.setPhysicsState(just like initially)

 

You probably won't need a .fixMyBarRotation() because... as stated earlier... sometimes .setPhysicsState resets the rotation automatically.

 

Essentially, once per frame, you shut off physics for the bar, fix any positional problems with the bar, and then setPhysicsState on the bar again.... which should null-out any ball-caused rotation.

 

And maybe... IF you DO this... and then lower the mass on the bar again, MAYBE you will see the ball actually "shoot" away from a bar.  This happens because you are moving the bar forward just after a ball has hit the bar backwards a small amount.  When you move the bar forward (to normal placement), and re-set its physics state... the ball may still be touching the physics imposter for the bar.  So, the ball might "spring" off the bar with more restitution than you planned-for.    But it's all fun.  Possibly, the lower the mass for bar, the more ball spring.  But you also have restitution settings on ball and bar... to adjust everything as you wish.

 

You might also try this same sneaky method for moving your bar left and right.  Instead of using applyImpulse to move the bar, use the animation loop:

 

bar.clearPhysicsState()

bar.adjustPos()  // reset bar z-position and check for +/-X movement needed (player input).  If needed, do it.

bar.setPhysicsState(just like initially)   // re-apply the physics state after the position adjustments.

 

Wow, huh?  Just a thought.  I don't know if this idea will help you, but maybe.  I HAVE used this method to position objects that were physics-active (most of the time). 

[Gamerazor]

thank you wingnut but i only had problem when the bar collided with the left wall but I have resolved this problem with this way:

move = (body,barra) -> s= 2.5 if body.moveLeft && barra.position.z > -5  barra.applyImpulse(new BABYLON.Vector3(0,0,-s),barra.position) else if body.moveRight  barra.applyImpulse(new BABYLON.Vector3(0,0,s),barra.position) body.body.linearVelocity.scaleEqual(0.92) body.body.angularVelocity.scaleEqual(0) return