how to calculate the force necessary to reach an exact height

[frosty cape]

#💻┃code-beginner message my contribution

[blissful loom]

float CalculateInitialVelocity(float jumpHeight, float fixedTimestep, float acceleration) {
    // start at 0 speed - this is at the top of the jump
    float speed = 0;

    // work backwards to get to starting speed
    for (float height = jumpHeight; height > 0; height -= speed * fixedTimestep) {
      speed += acceleration * fixedTimestep
    }

    return speed;
}

can you explain to me what it does

[frosty cape]

it works backwards

imagine yourself at 0 velocity at the top of the jump (the desired height)

it then simulates each fixed physics timestep, adding velocity as gravity would, until the object reaches the ground

the final velocity is the same as you would need to get to that height in the first place

[blissful loom]

oh

so basically

[frosty cape]

basically it's the same as if you drop an object off a height, then record its velocity as it hits the ground

that's the same velocity you'd need to throw the object to that height from the ground

[blissful loom]

if im at the desired height speed is 0, and then it calculates every physics frame until i get to 0?

[frosty cape]

yes

I'm not sure if there's a way to do it all at once (without a loop) but this should at least work as a starting point

[blissful loom]

i then do rb.addforce(CalculateInitialVelocity)

[frosty cape]

well this will just give you a float

so you'd use that as the y velocity you are assigning your player

something like cs rb.velocity = new(rb.velocity.x, CalculateInitialVelocity(desiredJumpHeight, Time.fixedDeltaTime, gravity), rb.velocity.z);

[blissful loom]

and then just jump in fixedupdate?

[frosty cape]

jump wherever you want to jump 🤷‍♂️

[blissful loom]

basically

FixedUpdate()
{
if (should be jumping)
rb.velocity...
}