gistfile1.txt

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

public class LinhaScript : MonoBehaviour {

    int numeroDeVertices = 0;
    LineRenderer linha;
    bool apertandoBotaoDoMouse = false;

	// Use this for initialization
	void Start () {
        linha = GetComponent<LineRenderer>();
	}
	
	// Update is called once per frame
	void Update () {
		
        if(Input.GetMouseButtonDown(0)){
            apertandoBotaoDoMouse = true;
        }

        if(Input.GetMouseButtonUp(0)){
            apertandoBotaoDoMouse = false;
        }

        if(apertandoBotaoDoMouse){
            CriarLinha();
        }else{
            DeletarLinha();
        }
	}

    void CriarLinha() {
        linha.SetVertexCount (numeroDeVertices + 1);

        Debug.Log(Input.mousePosition);

        Vector3 posicaoDoMouse = Camera.main.ScreenToWorldPoint(Input.mousePosition);

        linha.SetPosition(numeroDeVertices, posicaoDoMouse);
        numeroDeVertices++;
    }

    void DeletarLinha() {
        numeroDeVertices = 0;
        linha.SetVertexCount(0);
    }
}