Gizmo — A Tool Used in 3D Programs

A gizmo is a tool or visual interface element used in 3D programs for manipulating objects in a scene. A gizmo helps you interact with objects by providing convenient ways to transform, adjust, or visualize their properties. In other words, it is any graphical representation of a control for a modifier in a computer application.

Related concepts

• Wireframe
  A display mode for objects in which a gizmo can be useful for working with hidden faces.

• Viewport
  The area of the screen where scene objects and gizmos for manipulating them are displayed.

• Helpers
  Elements such as lines, spheres, or cubes that visualize an object's parameters (for example, a light's radius).

• Manipulator
  An alternative name for a gizmo, often used to describe transformation tools.

• Bounding Box
  A visual box bounding an object, which can be used together with a gizmo for transformation.

• Soft Selection
  A mode in which gizmo transformations are smoothly propagated to neighboring vertices or areas.

• Control Handles
  Gizmo elements for controlling the parameters of procedural effects (for example, the direction of a force).

• Keyframes
  A gizmo can help visualize object positions on the animation timeline.

• Spline Control
  A gizmo is used for manipulating spline control points.

• Custom Gizmo
  Custom gizmos created to visualize or control unique parameters (for example, a spell's area of effect in a game).

• Handles
  An alternative term for gizmo control elements.

• Gizmo Tool
  A general term for transformation tools in editors.

Below we will look at what a gizmo is in the context of various 3D programs:

1. Unity Gizmos

Unity is a program for creating games, applications, and VR/AR projects.​ It is easy to use, has a powerful game engine, and is cross-platform.

In Unity, a gizmo is a tool for visualizing and interacting with objects in a scene. They are used for:

• Moving, rotating, and scaling objects.
• Displaying auxiliary information (radii, areas of effect, etc.).
• Simplifying object configuration in the editor.

Types of gizmos in Unity:

• Transform gizmos: arrows for moving, circles for rotating, and cubes for scaling.
• Custom gizmos: developers can draw their own gizmos through scripts, for example, radii or areas of effect.

Example:

• Gizmos.DrawWireSphere draws a wireframe sphere around an object to visualize a radius.

Many gizmos are displayed as a built-in tool, but you can also extend the functionality and display a given gizmo with the customization and placement you need through code.

C# code example

To display a gizmo sphere of a given radius around a GameObject in Unity using C#, you need to use the OnDrawGizmos or OnDrawGizmosSelected method. This method is called by Unity in the editor to draw gizmo objects.

Here is an example of how to do this:

Code example:

using UnityEngine;

public class GizmoSphere : MonoBehaviour
{
    public float sphereRadius = 1.0f; // Sphere radius
    public Color gizmoColor = Color.green; // Gizmo color

    // Always display the gizmo
    private void OnDrawGizmos()
    {
        Gizmos.color = gizmoColor; // Set the gizmo color
        Gizmos.DrawWireSphere(transform.position, sphereRadius); // Draw the sphere
    }

    // Display the gizmo only when the object is selected
    private void OnDrawGizmosSelected()
    {
        Gizmos.color = gizmoColor; // Set the gizmo color
        Gizmos.DrawWireSphere(transform.position, sphereRadius); // Draw the sphere
    }
}

Explanation:

1. OnDrawGizmos: This method draws the gizmo at all times, regardless of whether the object is selected or not.
2. OnDrawGizmosSelected: The gizmo is drawn only when the object is selected in the inspector.
3. Gizmos.color: Sets the color for the displayed gizmos.
4. Gizmos.DrawWireSphere: Draws a wireframe sphere around the specified position with the given radius.

How to use:

1. Add the script to your GameObject.
2. Set the sphere radius (sphereRadius) and color (gizmoColor) through the inspector.
3. In edit mode you will see a sphere around the object.

Example in a scene:

• If you want the gizmo to show a radius of effect, for example, an enemy detection zone, this approach is very convenient. Result:
• You will get a visual indicator of the radius in the Unity editor, which will help you debug or configure objects.

2. Blender Gizmos

Blender is a program for modeling, texturing, rendering, animating, and creating VFX. Features: free, open source, an all-purpose tool.

In Blender, a gizmo is an interface element for working with objects in a 3D scene. Gizmos in Blender include:

• Transform manipulators:
  • Move: arrows for moving an object along the X, Y, Z axes.
  • Rotate: circles for rotating around axes.
  • Scale: lines for changing an object's size.
• Custom gizmos: for configuring shapes or tools (for example, in object edit mode).

Example:

• In edit mode, a gizmo helps modify an object's geometry, using the grid or axes as a reference.

3. Maya Gizmos

Maya is a program in which you can create professional 3D animation, modeling, characters, and special effects.

• Features: used in film, TV, and the game industry.

In Autodesk Maya, gizmos are also transformation tools:

• Move Tool: arrows for moving.
• Rotate Tool: rings for rotating an object.
• Scale Tool: cubes for scaling an object along the axes.
• Custom Gizmos: used in shaders, rigs, and other tools to visualize parameters or constraints.

Usage example:

• In Maya, a gizmo helps position bones in rigs or attach objects to a camera.

4. 3ds Max Gizmos

3ds Max is a program designed for visual modeling, rendering, and visualization of architecture, games, and animation.

• Features: its strength is architectural projects and visualization.

In 3ds Max, a gizmo plays a similar role:

• Transform gizmos: allow you to move, scale, and rotate objects.
• Modifier gizmos: visualize the area of effect of modifiers, such as Bend, Taper, Twist. The user can adjust the modifier's parameters by manipulating the gizmo.

Example:

• When using the Bend modifier, the gizmo displays the area of effect and the direction of the bend.

5. Unreal Engine Gizmos

Unreal Engine is a program for developing games, VR/AR, visualization, and interactive projects. Features: photorealistic graphics, a powerful engine, used in film and architecture.

In Unreal Engine, a gizmo is used to control objects and display information in the level editor:

• Transform gizmos: arrows, circles, and lines for manipulating objects in space.
• Visual gizmos: display the areas of effect of lights, cameras, triggers, and other components.

Example:

• When a light source is added to a scene, the gizmo shows its radius and direction.

6. Houdini Gizmos

Houdini is a program for creating procedural graphics, special effects (VFX), and simulations. Features: used in film, for procedural modeling and complex effects.

In Houdini, gizmos are used for:

• Manipulating geometry: controlling objects, nodes, or parameters through visual manipulators.
• Visualizing parameters: for example, the area of effect of a deformation or simulation.

Example:

• When creating a procedural simulation effect, a gizmo helps visualize the direction of a force or the area of effect.

Common features of gizmos in 3D programs:

• Transform tools: moving, rotating, scaling.
• Interactivity: a gizmo simplifies interaction with objects.
• Visualization: helps display parameters or areas of effect.

Differences:

• In Unity and Unreal Engine, gizmos focus more on editor tasks (level configuration, debugging).
• In Blender, Maya, and 3ds Max, gizmos are integrated into the modeling process.
• In Houdini, gizmos are closely tied to procedural effects.

Using gizmos significantly speeds up the workflow, making object control intuitive.

Unity is a program for creating games, applications, and VR/AR projects.​ It is easy to use, has a powerful game engine, and is cross-platform.

See also

• Pivot Point
• Local/Global Space
• Axis
• Snapping
• Collider
• Trigger
• Field of View
• Bounding Volume