Simple math, have I gone crazy?

Archived Forums Questions & Answers
1

I have one boxcollider walking on the ground in 2d game.

From one frame to another, I want to expand the collider’s size.y from 0.8 to 3.0.

Now how much should I move the collider upwards, for it to be standing on the ground again?

My logic tells me this is the way, but I might be wrong:

collider.size = new Vector2(1.5f, 3f);

difference = 3f - 0.8f; // 2.2f

player.transform.position = new Vector2(player.transform.position.x, player.transform.position.y + difference * 0.5f);

I’m not changing the center or anything. But this results in the player hanging a little higher over the ground than I expected.

So can someone tell me if the math here is wrong? Or is it something else, causing the trouble?

2

Hello,
I’m not familiar with the 2d side of unity but if you resize the collider won’t it push your model off the ground… therefore moving the transform.position.y of it?
I would recommend to check your position.y before and after expanding and then see how much you need to adjust it.
but as said - just a shot in the dark
regards,

3

Should be a simple proportion.

Evaluate the actual distance from the ground before the scaling, then solve this:

heightBefore : 0.2 = x : newScale

Where x is the new height.

it will lead you to:

x = (heightBefore*newScale)/0.2

Doing so you can also keep it stuck on the ground by evaluating the distance every frame as you increase the scale to the final level.