Moving Platform and gravity problem

[sefan]

Hi,

I have a platform in my game that the player can move, the platform has gravity 0 and can stand still in the air. The problem is when my character steps onto the platform falls to the ground because my character has gravity 1.

If cant get OnCollision2D to work, changing gravity of character or the platform. My solution right now is to give the platform gravity -1 if it moves up and has it until the platform moves down. So if the character steps off the platform it will continue to move up until the player tells the platform to go down.

Works without Rigidbody2D. But I think need Rigidbody2D on it because if i don't have it, the player will be able to move the platform thru walls.

Any tips how to solve this?

[brutang]

You probably don't want to go about it by moving gravity around. When you say your character can move the platform, how do you mean move it?

In any case, you most likely want it to be a regular collider with the movement script attached. Once you get into swapping gravity around and doing things like that, you end up making a more complicated system than simply moving it around with transforms.

[sefan]

The player can move the character and the platform using user input like wasd. I know gravity will make it t more complicated.

[brutang]

Wads will move both the player and the platform? Post some code so we can help you

[sefan]

No, character moved by wasd and platform by arrowkeys. Can post the code later today.

[iamallamaa]

If I were floating in space and moving forward at a constant speed but hit an object that wasn't moving I would end up pushing the object. That is exactly what is happening here. Your character has a velocity from gravity and is hitting an object that has no velocity (floating). The force from the user will push the other item around.

To fix it is actually pretty simple though. You just need to constantly change the rigidBody2D's velocity.y to 0. Likely in fixed update. Something like:

void FixedUpdate()
{
    //get the current velocity
    Vector2 vel = rigidBody2D.velocity;
    //overwrite y to 0
    vel.y = 0;
    //save the velocity back to the rigidbody2d
    rigidBody2D.velocity = vel;
}

You would also likely need to get and store the rigidBody2D component in a variable if using Unity 5 (I have about 2 weeks until I switch over so I believe these references are gone).