Hmm, I can’t think of a way to use the trail renderer on a non-moving object.
You could, however, use a [line renderer][1] instead, and manually set the positions of each segment of the line yourself through a script.
In the scripting reference, the line renderer has the [SetPosition][2] function which would be perfect for your needs.
Edit 1: Below is the code that could simulate a trail renderer when an object is static. To test this out, make a new object, put a line renderer on it, and slap on this script (and add in the values of course). The values I used for testing were: 10 for trail resolution, (2,0,0) for offset and 0.15f for lag time.
Edit 2: Added the ‘RequiredComponent’ attribute so you don’t even have to add a Line Renderer manually. Also this new code viewer on Unity’s website is cutting off my code … gah. Where did the scroll-bar go?
Edit 3: Added functionality to the script so that you can choose which local direction the trail follows. Rotating the object now makes the trail orient itself correctly.
using UnityEngine;
using System.Collections;
public class ManualTrail : MonoBehaviour
{
public int trailResolution;
LineRenderer lineRenderer;
Vector3[] lineSegmentPositions;
Vector3[] lineSegmentVelocities;
// This would be the distance between the individual points of the line renderer
public float offset;
Vector3 facingDirection;
public enum LocalDirections {XAxis, YAxis, ZAxis}
public LocalDirections localDirectionToUse;
// How far the points 'lag' behind each other in terms of position
public float lagTime;
Vector3 GetDirection()
{
switch(localDirectionToUse)
{
case LocalDirections.XAxis:
return transform.right;
case LocalDirections.YAxis:
return transform.up;
case LocalDirections.ZAxis:
return transform.forward;
}
Debug.LogError("The variable 'localDirectionToUse' on the 'ManualTrail' script, located on object " + name + ", was somehow invalid. Please investigate!");
return Vector3.zero;
}
// Use this for initialization
void Start ()
{
lineRenderer = GetComponent<LineRenderer>();
lineRenderer.SetVertexCount(trailResolution);
lineSegmentPositions = new Vector3[trailResolution];
lineSegmentVelocities = new Vector3[trailResolution];
facingDirection = GetDirection();
// Initialize our positions
for (int i = 0; i < lineSegmentPositions.Length; i++)
{
lineSegmentPositions *= new Vector3();*
_ lineSegmentVelocities = new Vector3();_
* if (i == 0)*
* {*
* // Set the first position to be at the base of the transform*
_ lineSegmentPositions = transform.position;
* }
else*
* {
// All subsequent positions would be an offset of the original position.
lineSegmentPositions = transform.position + (facingDirection * (offset * i));
}
}
}*_
* // Update is called once per frame*
* void Update ()*
* {*
* facingDirection = GetDirection();*
* for (int i = 0; i < lineSegmentPositions.Length; i++)*
* {*
* if (i == 0)*
* {*
* // We always want the first position to be exactly at the original position*
_ lineSegmentPositions = transform.position;
* }
else*
* {
// All others will follow the original with the offset that you set up*
lineSegmentPositions = Vector3.SmoothDamp(lineSegmentPositions, lineSegmentPositions[i - 1] + (facingDirection * offset), ref lineSegmentVelocities*, lagTime);
}*_
* // Once we’re done calculating where our position should be, set the line segment to be in its proper place*
_ lineRenderer.SetPosition(i, lineSegmentPositions*);
}
}
}
[1]: http://docs.unity3d.com/Manual/class-LineRenderer.html*_
_*[2]: http://docs.unity3d.com/ScriptReference/LineRenderer.SetPosition.html*_
