Bounce animation for my entities doesnt work correctly

I made a entity and i want to give it an animation by code(becaue geckolib doesnt work for java anymore ) and i saw 2 mods named panduras creatures and mowzies mobs that use their one methods for make the animation easier, but it doesnt work for me or at least correctly: 

 public static void bounce(ModelRenderer model, float speed, float degree, boolean bouncy, float f, float f1)
    {
        float bounce = (float) (Math.sin(f * speed) * f1 * degree - f1 * degree);
        if (bouncy) {
            bounce = (float) -Math.abs((Math.sin(f * speed) * f1 * degree));
        }
        model.rotationPointY += bounce;
    }

This exact code make the entity bounce up and down a bit, if i use the bounce method + what i saw on the video:

limbSwing = entity.ticksExisted;
        limbSwingAmount = 0.5f;
        float globalHeight = 1f;
        float globalSpeed = 1f;
        float globalDegree = 1f;

        Animations.bounce(root, 1F * globalSpeed, 2F * globalHeight, true, limbSwing, limbSwingAmount);

the model just elevates and doesnt stop, and i discovered that instead of model.rotationPointY += bounce i have to put model.rotationPointY = bounce: the entity bounces but it elevates half a block, https://imgur.com/a/uREqwih

i tried to subtract the Math, the bounce float, but i cant put the entity in the ground(it bounces but i dont need my entity half a block up)