Change physics size circle

Getting Started Newbie Questions
#1

Hi
I’m not too good at programming, so any help would be welcome

In my app i have a ball that increases in scale by 0.1 when it makes a collision with an enemy.
I know how to change the image size, but don’t know how to change the physics size of it.

One of the problems is that i have tryed to remove the physics from it to create again, but the function did nothing (is it because the object was moving?). I want the object to have the same velocity and direction on movment when i create the physics again (if removal is necessary).

Any one has a good way to do this physics size scalling thing (on one object only)?

Remember it is a ball, not a shaped object so scalefactor from physics editor does not work for me.

Thanks in advance
Best Regards

#2

you could try removing the body and adding it with the new radius

#3

Hi @thithous,

You can’t remove and then add a new physics body during the same application time-step as a collision. So, you’d need to perform that with a tiny delay (even 10 milliseconds), but the problem with that approach is that you’ll lose the velocity when you destroy the body. Even if you store the current velocity to a variable and reset it on the new body, you might notice a tiny “interruption” while the first body is destroyed and the new one is created.

For a better and smoother process, I suggest that you initially create a multi-element body using a series of concentric circles (of different sizes). Then, use pre-collision and PhysicsContact to determine which of these body parts is “active” for the object depending on its visual size.

Take care,

Brent

#4

ty man. i ill try the first aproach and see how it looks like…
If it really have a noticeable interruption, then ill try to learn how to use this pre-collision event and physics contact method.
How can i create a multi-element body? I don´t know how physics works so well.

anyway thanks again
You have been very helpfull.

edit: the first aproach worked for me, but how can i get the radius propertie value from the old physics body? can those properties be accessed (like friction, density, radius and bounce)?

#5

Hi @thithous,

If you haven’t located it already, I suggest you start at Corona University for learning about physics (and other things as needed):

http://coronalabs.com/resources/tutorials/physics-box2d/

Properties like radius and friction are not directly read-able from a body… you’d need to just set them as properties of the object when you create it, then access those properties later.

Take care,

Brent

#6

you could try removing the body and adding it with the new radius

#7

Hi @thithous,

You can’t remove and then add a new physics body during the same application time-step as a collision. So, you’d need to perform that with a tiny delay (even 10 milliseconds), but the problem with that approach is that you’ll lose the velocity when you destroy the body. Even if you store the current velocity to a variable and reset it on the new body, you might notice a tiny “interruption” while the first body is destroyed and the new one is created.

For a better and smoother process, I suggest that you initially create a multi-element body using a series of concentric circles (of different sizes). Then, use pre-collision and PhysicsContact to determine which of these body parts is “active” for the object depending on its visual size.

Take care,

Brent

#8

ty man. i ill try the first aproach and see how it looks like…
If it really have a noticeable interruption, then ill try to learn how to use this pre-collision event and physics contact method.
How can i create a multi-element body? I don´t know how physics works so well.

anyway thanks again
You have been very helpfull.

edit: the first aproach worked for me, but how can i get the radius propertie value from the old physics body? can those properties be accessed (like friction, density, radius and bounce)?

#9

Hi @thithous,

If you haven’t located it already, I suggest you start at Corona University for learning about physics (and other things as needed):

http://coronalabs.com/resources/tutorials/physics-box2d/

Properties like radius and friction are not directly read-able from a body… you’d need to just set them as properties of the object when you create it, then access those properties later.

Take care,

Brent