Modular Health System
Guides
Show a Health Bar

Show a Health Bar

🎯 Goal

Make a UI slider follow an object’s health.

🧰 What You Need

  • Health
  • A UI Slider

🪜 Steps

Create a slider

Add GameObject > UI > Slider. Keep Min Value 0 and Max Value 1, and set Value to 1 so the bar starts full. Turn off Interactable so players can’t drag it.

Hook On Health Changed

On the Health, click + under On Health Changed, drag the slider into the object field and pick Slider > value from the Dynamic float list at the top. Health is passed from 0 to 1, so it matches the slider’s range.

Style the bar

Delete the slider’s Handle Slide Area, then color the Background and the Fill, for example red behind green.

📐 Inspector Settings

FieldWhat it doesSet it to
On Health ChangedRaised with health from 0 to 1Slider.value (dynamic)

🧪 Example

The Simple Duck scene has a UI slider set from the duck’s On Health Changed. The Hitbox Boss and Health Pickup scenes use the same setup.

💡 Tips

  • On Health Changed only fires when health changes, so set the slider’s starting Value to match.
  • ResetHealth() raises On Health Changed with 1, so the bar refills when a player respawns.
  • For a bar above an enemy, use a World Space canvas as a child of the enemy. It needs a small script to turn it toward the camera.
  • Pick Image > fillAmount instead of a slider for a filled image bar.

🔗 Related

Add Hitboxes and Weak SpotsHandle Death and Respawn