Health Bar

Introduction

Health bars are common UI elements in games. They are similar to progress bars, so this example could be used to create either. This example explains how to create a health bar component.

Creating the Component

First we'll define the component:

1. Open Gum

2. Open or create a new Gum project

3. Right-click on the Components folder

4. Name the component "HealthBar"

5. Resize the HealthBar component so it is wider than it is tall. For example, assign Width to 200 and Height to 32.

Adding a Background

Next we'll add a background to our HealthBar Component

1. Drag+drop a ColoredRectangle into the HealthBar

   
2. Select the newly-created ColoredRectangleInstance

3. Select the Alignment tab

4. Click the Fill Dock button

   
5. Change the ColoredRectangleInstance color to black

   

Now we have a black background in our HealthBar

Creating an Inner Container

The HealthBar displays its current health with another rectangle. This second rectangle will be contained inside a container to provide a boundary. To add an inner container:

1. Drag+drop a Container onto the HealthBar

2. Select the Alignment tab

3. Enter a Margin value of 4

4. Click the Fill Dock button

Now we have a ContainerInstance with the proper margin

Adding the Foreground Rectangle

Finally we'll add the foreground rectangle which displays the health:

1. Drag+drop another ColoredRectangle onto the ContainerInstance. Be sure to drop it on ContainerInstance so that the newly-added ColoredRectangle is a child of the container

2. Click the Alignment tab

3. Set Margin back to 0

4. Click the Fill Dock button

5. Change the following values:

   1. X Units to Pixels from Left

   2. X Origin to Left

   3. Width to Percentage of Container

   4. Width to 100

Now, the Width value can change between 0 and 100 to indicate the health percentage.

Expose Width

Next we'll expose the inner ColoredRectangle's Width property so it can be assigned per HealthBar instance:

1. Select the inner ColoredRectangle instance

2. Right-click on its Width variable and select Expose Variable

   
3. Enter an appropriate name such as "Percentage" and click OK

Now we can add instances of the HealthBar to a screen and control its fill percentage.