Procedural Thermometer

I couldn't find any tutorials on this, so this is how I made
a simple programmatically controlled thermometer in Unreal Engine 5.

Demo video

1. Material Parameter Collection

First make a new Material Parameter Collection asset Add a new scalar parameter named "Temp" to this new asset.

2. Material

Then make a new material with the following nodes: The `Temp` parameter is a Material Parameter Collection, pointing to the MPC we created in the previous step.
This allows us to dynamically change this value by changing the `Temp` variable in the MPC at runtime.
As `Temp` fluctuates from [0.0, 1.0] the bar will change from 0 - 100% full

// Demo changing thermometer at runtime

void AThermometer::Tick(float DeltaTime)
{
    float lerpDuration = 2.0f;

    if (lerpTimeElapsed < lerpDuration)
    {
        // pci is the MPC we made
        if (pci)
        {
            // Convert the [0, 100] temp to [0.0 1.0]:
            float matTemp = CurrentTemp / 100.0f;

            pci->SetScalarParameterValue(FName("Temp"), FMath::Lerp(startLerpTemp, matTemp, lerpTimeElapsed / lerpDuration));

            lerpTimeElapsed += DeltaTime;
        }
    }
}
            

NOTE: You could create a Dynamic Material Instance instead of using a Material Parameter Collection here but that is more work.

Finally, use this Material in your static mesh thermometer asset's thermometer tube material slot.