Source:

using System.Collections;using System.Collections.Generic;using UnityEngine;public class AtwalPaint : MonoBehaviour {    public Material currentMaterial;    private Color paintColor = Color.red;    private float paintSize = 0.1f;    private bool isPress = false;    private LineRenderer lineRenderer;    private List
     
       positions = new List
      
       ();    private int lineCount = 0;    private void Update()    {        if (Input.GetMouseButtonDown(0))        {            isPress = true;            GameObject go = new GameObject("LineRenderer_" + lineCount);            go.transform.parent = gameObject.transform;            lineRenderer = go.AddComponent
       
        ();            lineRenderer.startColor = paintColor;            lineRenderer.endColor = paintColor;            lineRenderer.startWidth = paintSize;            lineRenderer.endWidth = paintSize;            lineRenderer.material = currentMaterial;            lineRenderer.numCapVertices = 5;            lineRenderer.numCornerVertices = 5;            lineCount++;            AddPosition();        }        if (isPress)        {            AddPosition();        }        if (Input.GetMouseButtonUp(0))        {            lineRenderer = null;            positions.Clear();            isPress = false;        }    }    void AddPosition()    {        Vector3 position = GetMousePoint();        if (positions.Count > 0)        {            if (Vector3.Distance(position, positions[positions.Count - 1]) < 0.1f)            {                return;            }        }        position.z = -0.02f * lineCount;        positions.Add(position);        lineRenderer.positionCount = positions.Count;        lineRenderer.SetPositions(positions.ToArray());    }    Vector3 GetMousePoint()    {        Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);        RaycastHit hit;        bool isCollider = Physics.Raycast(ray, out hit);        if (isCollider)        {            return hit.point;        }        return Vector3.zero;    }    #region color    public void OnRedColorChange(bool isOn)    {        if (isOn)        {            paintColor = Color.red;        }    }    public void OnGreenColorChange(bool isOn)    {        if (isOn)        {            paintColor = Color.green;        }    }    public void OnBlueColorChange(bool isOn)    {        if (isOn)        {            paintColor = Color.blue;        }    }    #endregion    #region size    public void On1SizeChange(bool isOn)    {        if (isOn)        {            paintSize = 0.1f;        }    }    public void On2SizeChange(bool isOn)    {        if (isOn)        {            paintSize = 0.2f;        }    }    public void On4SizeChange(bool isOn)    {        if (isOn)        {            paintSize = 0.4f;        }    }    #endregion}