How can I properly scale in-game objects using centimeters and meters in Unity?

Scaling In-Game Objects Using Centimeters and Meters in Unity

Unity’s default unit of measurement is meters, meaning that when you set a scale of 1 on a GameObject, it represents one meter in the Unity world. However, when developing games, especially those requiring precise dimensions such as architectural visualizations or simulation games, you may find it necessary to use centimeters for more accuracy. Here’s how to handle this conversion in Unity.

Understanding the Transform Scale Property

Each object in Unity has a Transform component that includes the scale property, which is critical for adjusting size. By default, Unity interprets this scale in meters. Therefore, an object with a scale of (1, 1, 1) is one cubic meter. To work in centimeters, you need to adjust this interpretation:

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• 1 m = 100 cm, therefore 1 unit on the scale should be divided by 100 to convert it to meters if you’re inputting dimensions in centimeters.

Scaling Objects to Centimeters

To scale objects to use centimeters:

• Set the object’s scale values directly by dividing the size in centimeters by 100. For example, if you want an object to be 200cm long, you should set its scale to (2, 1, 1) where the x component is 2 representing 200cm or 2m.
• You can write a utility script to automate this conversion for consistency:

public class ScaleConversion : MonoBehaviour {
    public Vector3 cmDimensions;
    
    void Start() {
        transform.localScale = cmDimensions / 100.0f;
    }
}

This script takes a Vector3 input in centimeters and automatically converts it to meters upon initialization.

Considerations for Unity World Building

While using a scale of centimeters, ensure:

• Physics and Colliders: Be consistent in sizing to avoid physics inconsistencies. Ensure that mesh colliders and any physics calculations align with your unit scale.
• Editor Snapping: Set precise grid snapping in the editor to align with your centimeter-based scaling.
• Light Baking: Smaller scales can affect lightmap resolutions, so adjust accordingly.

Conclusion

While Unity natively supports meters, converting to centimeters involves multiplication and division by 100 within your workflows. Understanding and adjusting other components such as lights, physics, and visuals to adhere to these units is equally essential to maintain a consistent and reliable game environment.