Creating thermometer-style UI meters for a game can be a visually effective way to display variables such as health, temperature, or progress. Before you decide to put UI elements in a game prototype, however, consider how other diagetic feedback within your game could accomplish the same thing- maybe an npc starts to change color or behave a certian way rather than show a health meter, for example.

This page will guide you through the basics of creating such meters in three different environments: Unity, Construct 3, and Processing. Each platform has its own set of tools and scripting languages, making it versatile for different types of projects.

Unity

Unity uses C# for scripting, which allows for a robust and flexible development environment. To create a thermometer-style meter in Unity, you can follow these steps:

1. Prepare the Assets: Design your thermometer graphics. You will need at least two images: the background (thermometer casing) and the fill (mercury). Import these images into Unity as Sprites.

2. Create UI Elements: In the Unity Editor, go to the hierarchy window, right-click, navigate to UI, and then select Image. Create two Image UI elements, one for the background and one for the fill. Place the fill image on top of the background image in the UI canvas.

3. Add a Script for the Fill Control: Create a new C# script and name it something relevant, like ThermometerMeter. This script will control the fill level of your thermometer. Attach this script to the fill UI element.

4. Scripting the Fill Level: Open the script and write code to adjust the fill level based on the game’s variables. You can use the RectTransform’s height or the Image component’s fill amount to simulate the mercury rising or falling.

using UnityEngine;
using UnityEngine.UI;

public class ThermometerMeter : MonoBehaviour
{
    public Image fillImage;
    public float maxValue = 100f;
    private float currentValue = 0f;

    // Call this method to update the thermometer
    public void SetCurrentValue(float value)
    {
        currentValue = value;
        fillImage.fillAmount = currentValue / maxValue;
    }
}

1. Update the Thermometer: Use the SetCurrentValue method to update the thermometer’s fill level based on your game’s logic.

Construct 3

Construct 3 is a visual scripting game engine, which makes it very accessible for beginners.

1. Prepare the Assets: Like in Unity, you’ll need two images for your thermometer. Import these into your Construct 3 project.

2. Create the Sprites: In Construct 3, create two sprites: one for the background and one for the fill. Position the fill sprite over the background.

3. Adjust the Fill Sprite: To simulate the fill level, you can adjust the height of the fill sprite dynamically based on game variables. Use the Set height action in the event sheet to change the fill sprite’s height according to your game logic.

4. Event Sheet Logic: Add events that modify the height of the fill sprite based on the game’s conditions. You can use global variables or instance variables to track the values that affect the thermometer’s level.

Processing

Processing is an excellent tool for artists and beginners in coding. It allows for quick prototyping, including creating simple UI elements like a thermometer.

1. Draw the Thermometer: Use Processing’s drawing functions (rect, ellipse, etc.) to draw the thermometer’s background and fill.

2. Create a Function to Update the Fill: Write a function that takes a value and adjusts the height or color of the thermometer’s fill based on this value.

int maxValue = 100;
int currentValue = 0;

void drawThermometer(int value) {
  currentValue = value;
  // Draw background
  fill(255);
  rect(50, 50, 50, 200);
  
  // Draw fill
  float fillHeight = map(currentValue, 0, maxValue, 0, 200);
  fill(255, 0, 0);
  rect(50, 250 - fillHeight, 50, fillHeight);
}

void draw() {
  background(220);
  drawThermometer(currentValue);
  // Update currentValue based on your game logic
}

1. Update the Display: In your draw loop, call the drawThermometer function with the current value you wish to display. This value could be tied to game events or player actions.

Conclusion

Each platform offers unique tools and methods for creating a thermometer-style UI meter. Unity provides a comprehensive environment for more complex projects, Construct 3 simplifies the process with visual scripting, and Processing offers a straightforward approach for prototypes and artistic projects. Choose the one that best fits your project’s needs and your comfort level with coding or visual scripting.