DebugTextHelper.cs

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

public class DebugTextHelper
    : SingletonMonoBehaviourOnDemand<DebugTextHelper>
{
    public abstract class MessageBase
    {
        public TextMesh text;
        public float expire;
        public float offset;

        public abstract Vector3 GetBasePosition();
        public abstract bool IsExpired();
    }

    public class MessageObject
        : MessageBase
    {
        public GameObject owner;

        public override Vector3 GetBasePosition()
        {
            return owner.transform.position;
        }

        public override bool IsExpired()
        {
            if (GameObjectExtension.IsDestroyed(owner))
                return true;

            if (!owner.activeSelf)
                return true;

            if (expire >= 0.0f && Time.time > expire)
                return true;

            return false;
        }
    }

    public class MessagePosition
        : MessageBase
    {
        public Vector3 position;

        public override Vector3 GetBasePosition()
        {
            return position;
        }

        public override bool IsExpired()
        {
            if (expire >= 0.0f && Time.time > expire)
                return true;

            return false;
        }
    }

    public List<MessageBase> Messages = new List<MessageBase>();
    public bool Enabled = false;

    [ConsoleCommand("debugtext.toggle", "shift+b")]
    public static void ToggleEnabled()
    {
        DebugTextHelper.Instance.Enabled = !DebugTextHelper.Instance.Enabled;
    }

    public void OnScriptReload()
    {
        gameObject.DestroyAllChildren();
        Messages.Clear();
    }

    public void RemoveExisting(GameObject obj)
    {
        var index = 0;
        while (index < Messages.Count)
        {
            var item = Messages[index];
            var owned = item as MessageObject;

            if (owned != null && owned.owner == obj)
            {
                Messages.Remove(item);
                Destroy(item.text);
                continue;
            }

            index++;
        }
    }

    public MessageBase Print(string str, Vector3 pos, float expire = 5.0f)
    {
        var text = TextHelper.MakeDebugText(str);
        text.color = new Color(0.2f, 0.2f, 0.2f);
        text.transform.position = pos;

        var actual_expire = expire < 0.0f ? expire : Time.time + expire;
        var message = new MessagePosition() { text = text, position = pos, expire = actual_expire, };

        Messages.Add(message);

        text.transform.SetParent(Instance.transform);

        if (!Enabled)
            text.gameObject.SetActive(false);

        return message;
    }

    public MessageBase Print(string str, GameObject obj, float expire = 5.0f)
    {
        if (!Enabled) return null;

        var text = TextHelper.MakeDebugText(str);
        text.transform.position = obj.transform.position;
        text.color = new Color(0.2f, 0.2f, 0.2f);
        
        var actual_expire = expire < 0.0f ? expire : Time.time + expire;
        var offset = obj.EstimateRadius();

        var message = new MessageObject() { text = text, owner = obj, expire = actual_expire, offset = offset, };

        Messages.Add(message);

        text.transform.SetParent(Instance.transform);

        if (!Enabled)
            text.gameObject.SetActive(false);

        return message;
    }

    public void Update()
    {
        var index = 0;

        var camera = PlayerCameraSupport.GetCamera();

        while (index < Messages.Count)
        {
            var item = Messages[index];
            if (item == null)
            {
                Messages.Remove(item);
                Destroy(item.text);
                continue;
            }

            var expired = item.IsExpired();

            if (!Enabled)
                expired = true;

            if (expired)
            {
                Messages.Remove(item);
                Destroy(item.text);
                continue;
            }

            if (item.expire > 0.0f)
                item.offset += Time.deltaTime * 0.01f;

            var ofs = Vector3.up * item.offset;
            var fade = Mathf.Clamp01(item.expire - Time.time);

            if (item.expire < 0.0f)
                fade = 1.0f;

            var pos = item.GetBasePosition();

            pos += ofs;

            item.text.transform.position = pos;
            item.text.transform.localScale = new Vector3(
                item.text.transform.localScale.x,
                item.text.transform.localScale.y * fade,
                item.text.transform.localScale.z
            );

            var look_ofs = item.text.transform.position - camera.transform.position;
            var look_dir = look_ofs.normalized;

            item.text.transform.rotation = Quaternion.LookRotation(look_dir, Vector3.up);

            index++;
        }
    }
}