I have empty gameobject with a box collider. when i select the empty gameobject it's showing the collider in the editor scene view window. but is there any way to color or mark the collider size lines in editor/runtime without selecting the gameobject ?

I want to see somehow and know when the player is leaving/entering the colliding area. The problem is that you don't see it in runtime.

I have two events, ontriggerenter and ontriggerexit but i want something visual to see when the player is leaving/entering the area.

private void OnTriggerExit(Collider other)
    {
        if (other.name == "Colliding Area")
        {
            GameObject go = Instantiate(positionMarkerPrefab);
            Renderer rend = go.GetComponent<Renderer>();
            rend.material.color = Color.red;

            StartCoroutine(SlowDown());
        }
    }

    private void OnTriggerEnter(Collider other)
    {
        if (other.name == "Colliding Area")
        {
            GameObject go = Instantiate(positionMarkerPrefab);
            Renderer rend = go.GetComponent<Renderer>();
            rend.material.color = Color.black;

            if (increaseSpeed == false)
            {
                enteredPositionBack = transform.position;
            }
        }
    }

CodePudding user response：

You can use OnDrawGizmos to draw the bounds of a box collider in runtime. But the lines will only be visible in the editors scene view. Here is an example:

private BoxCollider boxCollider = null;
    
private void Start()
{
    boxCollider = GetComponent<BoxCollider>();
}

private void OnDrawGizmos()
{
    if (boxCollider)
    {
        Matrix4x4 rotationMatrix = Matrix4x4.TRS(boxCollider.transform.position, boxCollider.transform.rotation, boxCollider.transform.lossyScale);
        Gizmos.matrix = rotationMatrix;
        Gizmos.DrawWireCube(boxCollider.center, boxCollider.size);
    }
}

However you can use line renderer to visualize the box collider bounds in game view. Here is an example, its not pretty but it gets the job done:

private List<LineRenderer> lines = new List<LineRenderer>();

private void Start()
{
    BoxCollider boxCollider = GetComponent<BoxCollider>();
    if (boxCollider != null)
    {
        Material material = new Material(Shader.Find("Unlit/Color"));
        Color color = Color.green;
        material.color = color;
        float width = 0.01f;
        Vector3 rightDir = boxCollider.transform.right.normalized;
        Vector3 forwardDir = boxCollider.transform.forward.normalized;
        Vector3 upDir = boxCollider.transform.up.normalized;
        Vector3 center = boxCollider.transform.position   boxCollider.center;
        Vector3 size = boxCollider.size;
        size.x *= boxCollider.transform.lossyScale.x;
        size.y *= boxCollider.transform.lossyScale.y;
        size.z *= boxCollider.transform.lossyScale.z;
        DrawLine(center   upDir * size.y / 2f   rightDir * size.x / 2f   forwardDir * size.z / 2f, center   upDir * size.y / 2f - rightDir * size.x / 2f   forwardDir * size.z / 2f, color, material, width);
        DrawLine(center - upDir * size.y / 2f   rightDir * size.x / 2f   forwardDir * size.z / 2f, center - upDir * size.y / 2f - rightDir * size.x / 2f   forwardDir * size.z / 2f, color, material, width);
        DrawLine(center   upDir * size.y / 2f   rightDir * size.x / 2f   forwardDir * size.z / 2f, center - upDir * size.y / 2f   rightDir * size.x / 2f   forwardDir * size.z / 2f, color, material, width);
        DrawLine(center   upDir * size.y / 2f - rightDir * size.x / 2f   forwardDir * size.z / 2f, center - upDir * size.y / 2f - rightDir * size.x / 2f   forwardDir * size.z / 2f, color, material, width);
        DrawLine(center   upDir * size.y / 2f   rightDir * size.x / 2f - forwardDir * size.z / 2f, center   upDir * size.y / 2f - rightDir * size.x / 2f - forwardDir * size.z / 2f, color, material, width);
        DrawLine(center - upDir * size.y / 2f   rightDir * size.x / 2f - forwardDir * size.z / 2f, center - upDir * size.y / 2f - rightDir * size.x / 2f - forwardDir * size.z / 2f, color, material, width);
        DrawLine(center   upDir * size.y / 2f   rightDir * size.x / 2f - forwardDir * size.z / 2f, center - upDir * size.y / 2f   rightDir * size.x / 2f - forwardDir * size.z / 2f, color, material, width);
        DrawLine(center   upDir * size.y / 2f - rightDir * size.x / 2f - forwardDir * size.z / 2f, center - upDir * size.y / 2f - rightDir * size.x / 2f - forwardDir * size.z / 2f, color, material, width);
        DrawLine(center   upDir * size.y / 2f   rightDir * size.x / 2f   forwardDir * size.z / 2f, center   upDir * size.y / 2f   rightDir * size.x / 2f - forwardDir * size.z / 2f, color, material, width);
        DrawLine(center - upDir * size.y / 2f   rightDir * size.x / 2f   forwardDir * size.z / 2f, center - upDir * size.y / 2f   rightDir * size.x / 2f - forwardDir * size.z / 2f, color, material, width);
        DrawLine(center   upDir * size.y / 2f - rightDir * size.x / 2f   forwardDir * size.z / 2f, center   upDir * size.y / 2f - rightDir * size.x / 2f - forwardDir * size.z / 2f, color, material, width);
        DrawLine(center - upDir * size.y / 2f - rightDir * size.x / 2f   forwardDir * size.z / 2f, center - upDir * size.y / 2f - rightDir * size.x / 2f - forwardDir * size.z / 2f, color, material, width);
    }
}

private void DrawLine(Vector3 start, Vector3 end, Color color, Material material, float width = 0.01f)
{
    LineRenderer line = new GameObject("Line_"   start.ToString()   "_"   end.ToString()).AddComponent<LineRenderer>();
    line.material = material;
    line.startColor = color;
    line.endColor = color;
    line.startWidth = width;
    line.endWidth = width;
    line.positionCount = 2;
    line.useWorldSpace = true;
    line.SetPosition(0, start);
    line.SetPosition(1, end);
    line.transform.SetParent(transform);
    lines.Add(line);
}

public void SetLinesColor(Color color)
{
    for (int i = 0; i < lines.Count; i  )
    {
        lines[i].material.color = color;
        lines[i].startColor = color;
        lines[i].endColor = color;
    }
}