CREATE A ENERGY / HEALTH BAR HUD

Now then, let's get started.

1. Open the  Play scene which you had created in the previous post. If you've not created the  Play scene, create a New Scene and save it as Play, of course you can name it whatever you want.

2. Once you open the scene, you should have a  Main Camera, I would suggest you to Position it at  (0, 1, -15) 

3. Add a  Directional Light to the scene by navigating to  Gameobject->Light->Directional Light. Position it at  (0, 1, -15) as well.

4. Add a  Cube to the scene from  Gameobject->3D Object->Cube. Rename it as  Player. Position it at  (-1, 1, -10). Add a  Rigidbody component to this Player and uncheck the  Use Gravity checkbox.

 5. Create another  Cube object and rename it as  Fire. Position it at  (2, 1, -10). Check the  Is Trigger checkbox of the Fire's  Box Collider component.

You can add a material to this  Fire if you want, just like I did.

6. It is now time to add a  Text UI component named Health, to indicate a  Health Bar HUD.

7. Place the  text so that it is visible on the  top left corner of the  Game screen. Make sure you move the anchor points with the text as well . 

The above image shows you the things that I configured. You can follow it if you like or you can configure it the way you want.
1 signifies the position of the Health text
2 I have renamed the  Text to  HealthText.
3 Signifies the  Position of the HelathText  Rect Transform and also it's  Anchor's min maxpositions. Also the  Text content is changed to  Health.
4 Best Fit is checked so as to make the Text  dynamic. Max and Min size are set.  Color of the font has been changed to  White.
(Overlook the error in the console)

8. Create another  Text element under the  Canvas named  GameOver. Position it wherever you want to with the anchor points placed at the four corners. Also check the  Best Fitcheckbox . Change the font color if you want to .

   
9. It is time to add a  Slider, which will be used to indicate the  Health of the Player . Place it besides the  Health text and resize it as per your needs with the anchors placed around the corners.

10. We will disable the slider handle  as we don't need it.

11. Change the  Slider Fill color to Green

12. Create a  C# script named  MovementScript in the  Scripts folder. Attach it to the  PlayerGameObject. Open this script and add the below code to it.

using UnityEngine;
using System.Collections;
using UnityEngine.UI;
public class MovementScript : MonoBehaviour {

 public Slider healthBarSlider;  //reference for slider
 public Text gameOverText;   //reference for text
 private bool isGameOver = false; //flag to see if game is over

 void Start(){
  gameOverText.enabled = false; //disable GameOver text on start
 }

 // Update is called once per frame
 void Update () {
  //check if game is over i.e., health is greater than 0
  if(!isGameOver)
   transform.Translate(Input.GetAxis("Horizontal")*Time.deltaTime*10f, 0, 0); //get input
 }

 //Check if player enters/stays on the fire
 void OnTriggerStay(Collider other){
  //if player triggers fire object and health is greater than 0
  if(other.gameObject.name=="Fire" && healthBarSlider.value>0){
   healthBarSlider.value -=.011f;  //reduce health
  }
  else{
   isGameOver = true;    //set game over to true
   gameOverText.enabled = true; //enable GameOver text
  }
 }
}

- In the  Start function we disable the  GameOver text as we need it to be displayed only when the health is  zero.
- The code above is very simple. The  Update function gets input from the  keyboard as long as the  isGameOver flag is  false. Press  Right Arrow to move the  Player to  Right and  Left Arrow to move it  Left. 
-  OnTriggerStay function checks for  contact between the  Player and  Fire object as long as the  slider value is greater than  zero. If the  Player is in contact with the  Fire, it's health will reduce at a rate of  0.01 units/frame. This value is reflected on the  Slider. If the health value is  zero, we will enable the  GameOver text.
(Note: The slider value is set to 1 by default)

  
13. Save the script and return to Unity. Add the  Slider and  GameOver text elements to the script reference fields as below:

Now, your  Health Bar HUD is all ready to be tested. Press the  Play button to test your scene. Use the left and right arrow keys to move the Player.

See you around.

Also check out,
Unity 4.6 New GUI - Create a Blinking / Flashing Text

Dynamic Canvas Using Canvas Scaler / Reference Resolution - New Unity 4.6 GUI

Unity 4.6 GUI - Create A Dynamic Menu With The New UI

Unity 4.6 GUI - Create A Health Bar HUD

Unity 4.6 GUI - Create A Level Select Scroll Menu

Unity 4.6 GUI - Create An Animated Menu

Unity 4.6 GUI - Create A Level Lock/Unlock System

Unity 4.6 GUI - Add Fade Between Scenes

Unity 4.6 GUI - Add A Loading Scene / Splash Screen

Unity 4.6 GUI - Create A Sliding Pause Menu

Unity 4.6 GUI - Create A Star Rating / Reward System