Unity Visual Scripting: How to Use Bolt/Visual Scripting

February 25, 2025

Tired of endless coding tutorials? Unity’s visual scripting lets you build games faster, even without mastering C#. Visual scripting tools like Bolt offer an accessible entry point to game development within Unity, bypassing traditional coding for simpler tasks or rapid prototyping. They empower designers and artists to contribute directly to gameplay logic.

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However, if you are looking for an even easier way to develop games, especially in the beginning, Wayline is a comprehensive game development platform designed to help game developers succeed.

Introduction to Visual Scripting in Unity with Bolt

What’s visual scripting? It’s a method of creating game logic using a visual, node-based interface instead of writing code. Benefits include faster prototyping, a lower barrier to entry for non-programmers, and increased collaboration between team members with different skill sets.

Visual scripting offers a range of benefits. Bolt’s features include a user-friendly interface, with drag-and-drop functionality and intuitive node organization. It features a comprehensive library of nodes and seamless integration with Unity.

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The system revolves around graphs (visual representations of logic), nodes (individual actions or operations), connections (linking nodes together to define the flow), and variables (data containers).

Bolt was initially a third-party asset but is now a first-party Unity solution, ensuring continued support and integration.

Setting Up and Configuring Bolt in Your Unity Project

Install Bolt through the Unity Asset Store or Package Manager. Optimize performance by adjusting scripting runtime version (Edit > Project Settings > Player > Other Settings > Scripting Runtime Version). Bolt settings allow you to customize node appearance (in Bolt/Editor/Visual Scripting/Theme) and graph behavior (in Bolt/Visual Scripting/Flow/Nesting).

These settings let you tailor the visual scripting environment to your preferences. The Bolt editor interface includes the Graph window (where you create and edit graphs), the Blackboard (for managing variables), and the Inspector (for configuring nodes). Create visual script graphs by right-clicking in the Project window and selecting “Create > Bolt > Flow Graph” or "State Graph".

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Core Concepts: Variables, Events, and Flow Control

Variables are your game’s memory. They hold everything from player health to enemy positions. They have data types (e.g., integer, float, string, boolean) and scope (global, object, or local).

Global variables are accessible from anywhere in the project; imagine a ‘game over’ state that needs to be accessed from any script.

Object variables are specific to a GameObject; consider a character’s health, unique to each character instance. Local variables exist only within a single graph; for example, a local variable might store the number of times a player has jumped in a single level. These variable types determine how and where data can be accessed.

Events trigger actions. Unity events (e.g., Awake, Start, Update) are built-in. Custom events can be created to trigger specific behaviors. Event handling involves listening for events and executing corresponding logic. When the player presses the jump button (an event), the character jumps.

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Flow control determines the order in which nodes are executed. Branching (e.g., If statements) executes different paths based on conditions. Loops (e.g., For Loop) repeat a sequence of nodes. Sequences execute nodes in order.

Interacting with Unity’s API Through Visual Scripting

Access and manipulate GameObjects and Components using nodes like GameObject.Find, GetComponent, and Set Variable. Using these, you can locate specific objects in your scene and modify their properties.

Control transforms (position, rotation, scale) with nodes like Transform.Translate, Transform.Rotate, and Transform.Scale. Use these to move and orient game objects in your scene. Use physics nodes (e.g., AddForce, AddTorque) to simulate movement and interactions, making objects respond to forces. Control animations using the Animator component and nodes like Animator.SetBool and Animator.SetTrigger to bring characters and objects to life.

To make an object jump on user input, link Input.GetKeyDown (spacebar) to Rigidbody.AddForce on a GameObject. These interactions allow you to create dynamic and reactive gameplay experiences.

Creating Simple Gameplay Mechanics with Bolt

Player movement: Use Input.GetAxis (Horizontal/Vertical) connected to a Transform.Translate node. The Input.GetAxis node outputs a value between -1 and 1 based on player input. Connect this output to the Transform.Translate node’s “Translation” input. This directly controls the GameObject’s movement in world space. Jumping uses Input.GetKeyDown (Space) connected to a Rigidbody.AddForce node. When Space is pressed, AddForce applies an upward force, causing the jump.

Basic enemy AI: Start with a GameObject.FindWithTag node to locate the player. Then use a Vector3.Distance node to calculate the distance between the enemy and the player. Feed these into a Branch node. If the distance is less than a certain value, use Transform.LookAt to make the enemy face the player, followed by Transform.Translate to move it forward.

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Interactive objects: Use a Collider.OnTriggerEnter event to detect when the player enters a trigger zone. Connect this to a Set Variable node to change a boolean variable (e.g., “isOpen”). Finally, use a Branch node to check the value of “isOpen” and activate or deactivate a GameObject (e.g., a door) using the SetActive node.

These mechanics serve as a foundation for building more complex and engaging gameplay experiences. However, if you need assets to complete your game after you’ve completed the game logic, consider using Strafekit. Imagine building a game with a Low Poly Fantasy Village made entirely with visual scripting!

Debugging and Troubleshooting Visual Scripts

Use Bolt’s debugging tools (breakpoints, step-by-step execution, variable inspection) to identify and resolve errors. Breakpoints pause execution at specific nodes. This is useful not only when a variable isn’t changing as expected, but also when a particular branch of logic isn’t being reached. Step-by-step execution allows you to walk through the graph one node at a time. Variable inspection displays the values of variables during execution.

Common errors include incorrect variable types, missing connections, and infinite loops. A common variable error involves using a string where a float is expected; check your variable types and ensure they match. Missing connections result in logic not being executed; trace your graph to ensure all nodes are connected. Infinite loops will freeze the game; use breakpoints to identify the loop and add a condition to break it. Test and validate visual script logic by playing the game and observing the behavior. Optimize performance by reducing the number of nodes, caching frequently used variables, and avoiding unnecessary calculations. To further optimize performance, consider Implementing Object Pooling in Unity for Performance.

Advanced Techniques and Best Practices

Create custom nodes and macros for reusable logic. Custom nodes encapsulate complex logic into a single, reusable node, like a door opening sequence. Macros are reusable graphs that can be instantiated multiple times. Integrate visual scripts with C# scripts by calling C# methods from Bolt and vice versa.

Use Bolt for prototyping and rapid iteration to quickly test ideas and refine gameplay mechanics. Visual scripting bridges the gap between designers, artists, and programmers, fostering clearer communication and shared ownership of gameplay mechanics.

Resources and Further Learning

Official Bolt documentation.
Unity forums for visual scripting support.
Recommended books/courses on visual scripting.
Explore state machines.

Dive into Bolt and unleash your creative potential in Unity!