27
2017
Drawing Lines
An article by 
Hi dear reader!
In this tutorial we want to learn how to draw a line in unity by user mouse movement and interaction.
First we need a component that would be able to render simple lines.
Our choice is Line Renderer, this component is able to renderer lines between given positions so we can pass mouse position and let it to render them.
Getting Started
- Create or Open an Empty scene
- Create a new Empty Game Object
- Create a new c# script and name it DrawLine then put the below script into it
Now, attach the DrawLine script to Created Empty Game Object and Play the game.
Press primary mouse button and move your mouse around screen, as you can see the line goes to draw lines in your mouse position.
Explanation
In the script we first check the mouse primary button is pressed or not, when it is pressed we go to next step and try to get the mouse position in world space. After that we try to check if the mouse position isn’t exists in the line points, if the point doesn’t exists then we increase the line positions count and then we add mouse position to line positions and all done.
In the next tutorial we will try to use the line drawing in 2d mode and add a collider to the line.
Resources
This code mainly gathered from a gist and also is available in Unity Library
Thanks for reading.
Source Code
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| using System.Collections; | |
| using System.Collections.Generic; | |
| using UnityEngine; | |
| public class DrawLine : MonoBehaviour | |
| { | |
| [SerializeField] | |
| protected LineRenderer m_LineRenderer; | |
| [SerializeField] | |
| protected Camera m_Camera; | |
| protected List<Vector3> m_Points; | |
| public virtual LineRenderer lineRenderer | |
| { | |
| get | |
| { | |
| return m_LineRenderer; | |
| } | |
| } | |
| public virtual new Camera camera | |
| { | |
| get | |
| { | |
| return m_Camera; | |
| } | |
| } | |
| public virtual List<Vector3> points | |
| { | |
| get | |
| { | |
| return m_Points; | |
| } | |
| } | |
| protected virtual void Awake () | |
| { | |
| if ( m_LineRenderer == null ) | |
| { | |
| Debug.LogWarning ( "DrawLine: Line Renderer not assigned, Adding and Using default Line Renderer." ); | |
| CreateDefaultLineRenderer (); | |
| } | |
| if ( m_Camera == null ) | |
| { | |
| Debug.LogWarning ( "DrawLine: Camera not assigned, Using Main Camera or Creating Camera if main not exists." ); | |
| CreateDefaultCamera (); | |
| } | |
| m_Points = new List<Vector3> (); | |
| } | |
| protected virtual void Update () | |
| { | |
| if ( Input.GetMouseButtonDown ( 0 ) ) | |
| { | |
| Reset (); | |
| } | |
| if ( Input.GetMouseButton ( 0 ) ) | |
| { | |
| Vector3 mousePosition = m_Camera.ScreenToWorldPoint ( Input.mousePosition ); | |
| mousePosition.z = m_LineRenderer.transform.position.z; | |
| if ( !m_Points.Contains ( mousePosition ) ) | |
| { | |
| m_Points.Add ( mousePosition ); | |
| m_LineRenderer.positionCount = m_Points.Count; | |
| m_LineRenderer.SetPosition ( m_LineRenderer.positionCount – 1, mousePosition ); | |
| } | |
| } | |
| } | |
| protected virtual void Reset () | |
| { | |
| if ( m_LineRenderer != null ) | |
| { | |
| m_LineRenderer.positionCount = 0; | |
| } | |
| if ( m_Points != null ) | |
| { | |
| m_Points.Clear (); | |
| } | |
| } | |
| protected virtual void CreateDefaultLineRenderer () | |
| { | |
| m_LineRenderer = gameObject.AddComponent<LineRenderer> (); | |
| m_LineRenderer.positionCount = 0; | |
| m_LineRenderer.material = new Material ( Shader.Find ( "Particles/Additive" ) ); | |
| m_LineRenderer.startColor = Color.white; | |
| m_LineRenderer.endColor = Color.white; | |
| m_LineRenderer.startWidth = 0.3f; | |
| m_LineRenderer.endWidth = 0.3f; | |
| m_LineRenderer.useWorldSpace = true; | |
| } | |
| protected virtual void CreateDefaultCamera () | |
| { | |
| m_Camera = Camera.main; | |
| if ( m_Camera == null ) | |
| { | |
| m_Camera = gameObject.AddComponent<Camera> (); | |
| } | |
| m_Camera.orthographic = true; | |
| } | |
| } |
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Is it possible to draw on perspective camera too?
Thanks for the question ❤️
Yes, it is possible.
Minor Changes in input I achieved this for the perspective camera. Sincere thanks Buddy
Thanks for your response. Is it possible by changing the Camera.orthographic to perspective?