[1.16.5] Formula for brake force

[J3ramy]

Hey guys,

I am struggling a long time to figure out how to create a formula for my mod.

 

Overview:

I created a brake rail which should brake down a minecart when it's on it.

I found this formula in the internet and applied it:

Spoiler

this.currentBrakeForce = (Math.pow(targetVelocity, 2) - Math.pow(entryVelocity, 2)) / (2 * brakerunLength)

 

The minecart has an entry speed of 12m/s, the target velocity is 8m/s and the break run is 1m because it's one block.

 

I slow down the cart by multiplying the result of this formula with the current motion of the cart:

Spoiler

train.setMotion(train.getMotion().multiply(this.currentBrakeForce, 0, this.currentBrakeForce));

 

 

I figured out another thing: The wiki says that that 8m/s are 1.2 in motion.

So I changed the formula depending on the motion (I don't know if this is right but it made sense to me):

Spoiler

(0.15 * entryVelocity) / Math.abs(((Math.pow(targetVelocity, 2) - Math.pow(entryVelocity, 2)) / (2 * brakerunLength)));

 

Why 0.15?

As mentioned before 8m/s are 1.2.

So, 1m/s = 0.15 -> (8/1.2).

And then I multiplied it with the entry speed because it has to be changed to the "motion internal unit"?!

 

I am really frustrated right know, because I tried a lot of different changes within the formula. The problem is maybe the multiplication with the motion? I don't know.

Maybe someone can help me 

Thanks in advance!

[Draco18s]

3 hours ago, J3ramy said:

The wiki says that that 8m/s are 1.2 in motion.

Not sure where you're seeing this. BTW, minecarts already have a maximum speed of 8m/s per axis.

[J3ramy]

Maybe I should mention it. I changed the max speed and max speed on rail to 16m/s.

But my question is more, how do I convert the calculated force to the Minecraft motion?

[Draco18s]

Not sure, I haven't dug into the minecart code that much.

The only problem I see is that this:
Math.pow(targetVelocity, 2) - Math.pow(entryVelocity, 2)
Is guaranteed to return a negative value, which when multiplied against entity motion would cause the entity to reverse direction.

[J3ramy]

Yeah I tried it with Math.abs but it isn’t working either…

[Thorius]

I might have understood it wrong, but if you are simply multiplying the x and z component of the velocity vector, then don't you just need the ratio between the target and entry velocity? So shouldn't your brake"force" be targetVelocity/entryVelocity?

[J3ramy]

Hey Thorius,

I will try it tonight when I’m at home again but it seems like it could work. I’ll keep you up to date 

[J3ramy]

Finally I managed to check it.

It works perfectly.

Thank you all!

[Thorius]

You should know that this formula will also accelerate the carts to the specified speed. If you want to avoid that, use Math.min(brakeforce, 1).