Trail Renderer Local Space?

Unity Engine
1

I’ve been trying out the Trail renderer and it works fine. However i’m currently experiencing a problem that I can’t have the Trail renderer in local space only.

Here’s an image to explain my situation more:

Is it even possible to have it on local space? If so, could anyone point me in the right direction?

Thanks in forward!

2

I’ve been looking for the exact same thing, and all I came up with was this: http://forum.unity3d.com/threads/88715-Trail-and-local-move

Maybe it’s time to write my own?

3

This was my solution to the same problem:

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

public class TrailRenderer_Local : MonoBehaviour {

    // Author: Eric Hodgson 2017

    // NOTE: This script should be placed on the parent of the object that's moving.
    //  It should be drawn in the parent's local space, and move/rotate with the parent.
    //  If the trail script is on the moving object, the entire trail will move and
    //   rotate with the object itself, instead of leaving a trail behind in it's 
    //   parent's coordinate system.
    public Transform objToFollow;   //  Object that is leaving the trail


    private LineRenderer myLine;    //  internal pointer to LineRenderer Component

    public float distIncrement = 0.1f;      // How far should the object move before leaving a new trail point
    private Vector3 lastPosition;           // internal log of last trail point... could also use myLine.GetPosition(myLine.numPositions)

    public bool limitTrailLength = false;   // Toggle this to make trail be a finite number of segments
    public int maxPositions = 10;           // Set the number of segments here

    // Use this for initialization
    void Start() {
        // Get a pointer to the LineRenderer component so we can manipulate it
        myLine = GetComponent<LineRenderer>();
        // ....and make sure it's set to use local space
        myLine.useWorldSpace = false;
        // Reset the trail
        Reset();
    }

    void Reset() {
        // Wipe out any old positions in the LineRenderer
        myLine.numPositions = 0;
        // Then set the first position to our object's current local position
        AddPoint(objToFollow.localPosition);
    }

    // Add a new point to the line renderer on demand
    void AddPoint(Vector3 newPoint) {
        // Increase the number of positions to render by 1
        myLine.numPositions += 1;
        // Set the new, last item in the Vector3 list to our new point
        myLine.SetPosition(myLine.numPositions - 1, newPoint);

        // Check to see if the list is too long
        if (limitTrailLength && myLine.numPositions > maxPositions) {
            // ...and discard old positions if necessary
            TruncatePositions(maxPositions);
        }

        // Log this position as the last one logged
        lastPosition = newPoint;
    }


    // Shorten position list to the desired amount, discarding old values
    void TruncatePositions(int newLength) {
        // Create a temporary list of the desired length
        Vector3[] tempList = new Vector3[newLength];
        // Calculate how many extra items will need to be cut out from the original list
        int nExtraItems = myLine.numPositions - newLength;
        // Loop through original list and add newest X items to temp list
        for (int i=0; i<newLength; i++) {
            // shift index by nExtraItems... e.g., if 2 extras, start at index 2 instead of index 0
            tempList[i] = myLine.GetPosition(i + nExtraItems);
        }

        // Set the LineRenderer's position list length to the appropriate amount
        myLine.numPositions = newLength;
        // ...and use our tempList to fill it's positions appropriately
        myLine.SetPositions(tempList);
    }


    // Update is called once per frame
    void Update () {
        // Get the current position of the object in local space
        Vector3 curPosition = objToFollow.localPosition;
        // Check to see if object has moved far enough
        if (Vector3.Distance(curPosition, lastPosition) > distIncrement) {
            // ..and add the point to the trail if so
            AddPoint(curPosition);
           
        }
    }
}
12 Likes
4

Dude thank you so much! You’re the best solution I’ve found in the internetz