calculate and render an arc affected by gravity

ArcRender.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class ArcRender : MonoBehaviour
{
	public int Count = 10;
	public float PowerMultiplier = 2;

	public Transform handle;

	float GravityAmount = -9.81f;
	float FixedTimestep = 0.01f;
	LineRenderer lineRenderer;

	void Start ()
	{
		if (handle == null)
		{
			Debug.LogWarning("handle is just for getting the direction vector");
			var go = new GameObject("handle");
			go.transform.position = transform.position + new Vector3(-1,-1,-1);
			handle = go.transform;
		}

		lineRenderer = GetComponent<LineRenderer>();
		if (lineRenderer)
		{
			lineRenderer.useWorldSpace = true;
			lineRenderer.positionCount = Count;
		}

		FixedTimestep = Time.fixedDeltaTime;
	}

	//the direction and magnitude to draw the line
	public Vector3 GetDirectionVector()
	{
		return (transform.position - handle.position) * PowerMultiplier;
	}

	//draw debug rays and update line renderer
	void Update ()
	{
		var positions = GetPositions(Count);

		for(int i = 0;i<positions.Count-1;i++)
		{
			Debug.DrawLine(positions[i],positions[i+1],Color.green);
		}

		if (lineRenderer != null)
		{
			lineRenderer.SetPositions(positions.ToArray());
		}
	}

	public List<Vector3> GetPositions(int positionCount)
	{
		List<Vector3> arcPositions = new List<Vector3>();

		Vector3 vector = GetDirectionVector() * FixedTimestep;
		Vector3 gravityvector = Vector3.up * GravityAmount;

		Vector3 lastVector = vector;
		Vector3 lastPosition = transform.position;
		arcPositions.Add(lastPosition);
		for(int i = 0; i< positionCount;i++)
		{
			//Debug.DrawRay(lastPosition,lastVector,Color.red);
			lastPosition += lastVector;
			lastVector += gravityvector * FixedTimestep;
			arcPositions.Add(lastPosition);
		}
		return arcPositions;
	}
}