Can gravity be disabled for a single object in the BGE?

Question

I created a scene with my camera parented to a player object and a few bouncing balls. I want the player to stand still (in space) unless moved by user interaction and interact by the balls when hit.

As soon as the game engine starts my player is dragged by gravity I couldn't find a property to control the influence of gravity in KX_GameObject as suggested by this outdated BA Thread.

File or testing: .blend

Answer 1

You can do that with logic bricks alone. So you do not need a constantly running python script.

Assuming your object has a mass of 1.0:

activated once with an Alyways Sensor [with deactivated True Level Triggering]

Remarks

• If you have a different mass and/or gravity, you multiply the gravity with the mass to get the counterforce: Force.z = gravity * mass
• Ensure the counterforce is given in global coordinates ([L] must be disabled), otherwise you get a rocket.
• Gravity is per convention a force along the global -Z axis. The counterforce must be along +Z (positive Z-coordinate)
• Do not wonder that your floating object is moving when touched, that is normal. The only reason it would stop by itself would be air friction. This is not part of the gravity.
• This method does not work with swimming/diving objects as the counter force would not be constant.

Answer 2

The gravity can be almost completly neutralized with this snippet added to a BG python controller:

sce = bge.logic.getCurrentScene()
ob = sce.objects['Player']
ob.applyForce([0, 0, 19.6]) 

Note that 'Player' is the player game object.

I have no idea why I need to apply 2 times of the gravity constant (9.8 from World/Physics/Gravity) but this way it works.

Answer 3

I don't know about disabling gravity, but you can set the physics type of your player to "Character" and set the "Fall Speed Max" to 0:

Yout object will still be able to collide with other objects in the scene, but will not fall down because of gravity.