using UnityEngine;

[System.Serializable]
public class Bezier : System.Object    
{
    public Vector3 p0;
    public Vector3 p1;
    public Vector3 p2;
    public Vector3 p3;
    public float ti = 0f;
    private Vector3 b0 = Vector3.zero;
    private Vector3 b1 = Vector3.zero;
    private Vector3 b2 = Vector3.zero;
    private Vector3 b3 = Vector3.zero;
    private float Ax;
    private float Ay;
    private float Az;
    private float Bx;
    private float By;
    private float Bz;
    private float Cx;
    private float Cy;
    private float Cz;
    
    // Init function v0 = 1st point, v1 = handle of the 1st point , v2 = handle of the 2nd point, v3 = 2nd point
    // handle1 = v0 + v1
    // handle2 = v3 + v2
    
    public Bezier( Vector3 v0, Vector3 v1, Vector3 v2, Vector3 v3 )
    {
        this.p0 = v0;
        this.p1 = v1;
        this.p2 = v2;
        this.p3 = v3;
    }
    
    // 0.0 >= t <= 1.0
    public Vector3 GetPointAtTime( float t )    
    {
        this.CheckConstant();
        float t2 = t * t;
        float t3 = t * t * t;
        float x = this.Ax * t3 + this.Bx * t2 + this.Cx * t + p0.x;
        float y = this.Ay * t3 + this.By * t2 + this.Cy * t + p0.y;
        float z = this.Az * t3 + this.Bz * t2 + this.Cz * t + p0.z;
        return new Vector3( x, y, z );
    }
    
    private void SetConstant()    
    {
        this.Cx = 3f * ( ( this.p0.x + this.p1.x ) - this.p0.x );
        this.Bx = 3f * ( ( this.p3.x + this.p2.x ) - ( this.p0.x + this.p1.x ) ) - this.Cx;
        this.Ax = this.p3.x - this.p0.x - this.Cx - this.Bx;
        this.Cy = 3f * ( ( this.p0.y + this.p1.y ) - this.p0.y );
        this.By = 3f * ( ( this.p3.y + this.p2.y ) - ( this.p0.y + this.p1.y ) ) - this.Cy;
        this.Ay = this.p3.y - this.p0.y - this.Cy - this.By;
        this.Cz = 3f * ( ( this.p0.z + this.p1.z ) - this.p0.z );
        this.Bz = 3f * ( ( this.p3.z + this.p2.z ) - ( this.p0.z + this.p1.z ) ) - this.Cz;
        this.Az = this.p3.z - this.p0.z - this.Cz - this.Bz;
    }
    
    // Check if p0, p1, p2 or p3 have changed
    private void CheckConstant()
    {
        if( this.p0 != this.b0 || this.p1 != this.b1 || this.p2 != this.b2 || this.p3 != this.b3 )
        {
            this.SetConstant();
            this.b0 = this.p0;
            this.b1 = this.p1;
            this.b2 = this.p2;
            this.b3 = this.p3;
        }
    }
}

using UnityEngine;

public class MyBezier : MonoBehaviour
{
    public Bezier myBezier;    
    public GameObject Yellowline;
    private LineRenderer YellowlineRenderer;
    public float hSliderValue0;
    public float hSliderValue1;
    
    void Start()
    {
        YellowlineRenderer = Yellowline.GetComponent<LineRenderer>();
        YellowlineRenderer.SetVertexCount(100);
    }
    
    void OnGUI()
    {
        hSliderValue0 = GUI.HorizontalSlider(new Rect(25, 25, 100, 30), hSliderValue0, -5.0F, 5.0F);
        hSliderValue1 = GUI.HorizontalSlider(new Rect(25, 70, 100, 30), hSliderValue1, -5.0F, 5.0F);
    }

    void Update()
    {
        myBezier = new Bezier( new Vector3( -5f, 0f, 0f ),  new Vector3( hSliderValue1, hSliderValue0 , 0f ),  new Vector3( hSliderValue1, hSliderValue0, 0f ), new Vector3( 5f, 0f, 0f ) );
        for(int i =1; i <= 100; i++)
        {
            Vector3 vec = myBezier.GetPointAtTime( (float)(i *0.01) );
            YellowlineRenderer.SetPosition(i -1,vec);
        }
    }
}