Unity LineRender (マウスで線を描く)

DrawLine.cs

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


/**
 * https://unitycoder.com/blog/2017/08/27/drawing-lines/
 *
 * Unity ver.2018.3.13f1 で確認
 */

public class DrawLine : MonoBehaviour {

    [field: SerializeField]
    public LineRenderer lineRenderer { get; private set; }

    [field: SerializeField]
    public Camera camera { get; private set; }

    [field: SerializeField]
    public List<Vector3> points { get; private set; }


    private void Awake() {
        if (this.lineRenderer == null) {
            Debug.LogWarning("DrawLine: Line Renderer not assigned, Adding and Using default Line Renderer.");
            this.lineRenderer = this.CreateDefaultLineRenderer();
        }

        if (this.camera == null) {
            Debug.LogWarning("DrawLine: Camera not assigned, Using Main Camera or Creating Camera if main not exists.");

            this.camera = this.CreateDefaultCamera();
        }

        this.points = new List<Vector3>();
    }

    private void Update() {
        if (Input.GetMouseButtonDown(0)) {
            this.Reset();
        }

        if (Input.GetMouseButton(0)) {
            var mousePosition = this.camera.ScreenToWorldPoint(Input.mousePosition);
            mousePosition.z = this.lineRenderer.transform.position.z;

            if ( !this.points.Contains(mousePosition)) {
                this.points.Add(mousePosition);
                this.lineRenderer.positionCount = this.points.Count;
                this.lineRenderer.SetPosition(this.lineRenderer.positionCount - 1, mousePosition);
            }
        }
    }


    protected virtual void Reset() {
        if (this.lineRenderer != null) {
            this.lineRenderer.positionCount = 0;
        }
        if (this.points != null) {
            this.points.Clear();
        }
    }

    protected virtual LineRenderer CreateDefaultLineRenderer() {
        var renderer = this.gameObject.AddComponent<LineRenderer>();

        renderer.positionCount = 0;
        renderer.material = new Material(Shader.Find("Mobile/Particles/Additive"));
        renderer.startColor = Color.white;
        renderer.endColor = Color.white;
        renderer.startWidth = 0.3f;
        renderer.endWidth = 0.3f;
        renderer.useWorldSpace = true;

        return renderer;
    }

    protected virtual Camera CreateDefaultCamera() {

        var camera = Camera.main;
        if (camera == null) {
            camera = this.gameObject.AddComponent<Camera>();
        }

        if (camera != null) {
            camera.orthographic = true;
        }

        return camera;
    } 
}