XR Building Blocks

The building blocks system is an overlay window in the scene view that can help you quickly access commonly used items in your project. To open the building blocks overlay click on the hamburger menu on the scene view > Overlay menu Or move the mouse over the scene view and press the "tilde" key. Afterwards just enable the Building Blocks overlay

A Building block is essentially a button that executes a script; be this to instantiate a prefab, create a scripted object or execute an action.

Building Blocks and Building Block Sections

Building blocks can be arranged by sections, or can belong to no section at all. Building blocks that do not belong to any section are considered Unsectioned building blocks -- and are not recommended due to their lack of organization. A building block section contains a set of building blocks that can belong to the same package, workflow, or topic.

To create a building block section, your class must implement the IBuildingBlockSection interface. In order to add a building block, your class must implement the IBuildingBlock interface.

Both sections and blocks have a name and an icon path so that they can be distinguished in the UI, either when they are docked, or when displayed as a UI overlay.

Building block sections are responsible for providing the building blocks they contain. They do this by returning a collection of the building block instances through the IEnumerable<IBuildingBlock> GetBuildingBlocks() method.

The BuildingBlockItem Attribute

In order for the building block system to recognize your sections, those building block section implementations must have a [BuildingBlockItem(Priority = k_SectionPriority)] attribute. The BuildingBlockManager discovers those sections through that attribute.

Individual building block implementations may also have the attribute. In this case, the building block will be treated as an unsectioned building block by the BuildingBlockManager, and will be displayed outside of any section. For organizational purposes, this is not recommended.

The Priority member in this attribute is used to define the order in which sections appear in the building blocks overlay. A smaller value (int) assigned to the Priority member will result in the building block section appearing higher within the overlay window compared to other building block sections.

Unsectioned building blocks are presented before sections, regardless of priority, and the priorities specified for those individual building block items also affect their display order within other unsectioned blocks.

Prefab creator building block.

The PrefabCreatorBuildingBlock is a special type of building block that can be used in any building block section to simply instantiate a prefab. With this you don't need to create a building block for the sole purpose of instantiating prefabs.

Prefab creator building blocks are created inside the BuildingBlockSection implementations and added in the GetBuildingBlocks() method as mentioned above.

Example of a Building Block implementation

The example below creates two building blocks (Scripted Building Block and Prefab Creator Block) under a section called My Block Section.

The scripted building block (when pressed) will create an empty game object called "Empty Object" and the Prefab Creator Block building block shows how to use the PrefabCreatorBuildingBlock block mentioned above; you will need to set the m_PrefabAssetPath variable accordingly to point to a prefab for it to instantiate correctly.

using System.Collections.Generic;
using System.Linq;
using Unity.XR.CoreUtils.Editor.BuildingBlocks;
using UnityEditor;
using UnityEngine;

class ScriptedBuildingBlockSample : IBuildingBlock
{
    const string k_Id = "Scripted Building Block";
    const string k_BuildingBlockPath = "GameObject/MySection/" + k_Id;
    const string k_IconPath = "buildingblockIcon";
    const string k_Tooltip = "My Scripted Building Block tooltip";
    const int k_SectionPriority = 10;

    public string Id => k_Id;
    public string IconPath => k_IconPath;
    public bool IsEnabled => true;
    public string Tooltip => k_Tooltip;

    static void DoInterestingStuff()
    {
        var createdInstance = new GameObject("Empty Object");
        // Do more interesting stuff her
    }

    public void ExecuteBuildingBlock() => DoInterestingStuff();

    // Each building block should have an accompanying MenuItem as a good practice, we add them here.
    [MenuItem(k_BuildingBlockPath, false, k_SectionPriority)]
    public static void ExecuteMenuItem(MenuCommand command) => DoInterestingStuff();
}

[BuildingBlockItem(Priority = k_SectionPriority)]
class BuildingBlockSection1 : IBuildingBlockSection
{
    const string k_SectionId = "My Block Section";
    public string SectionId => k_SectionId;

    const string k_SectionIconPath = "Building/Block/Section/Icon/Path";
    public string SectionIconPath => k_SectionIconPath;
    const int k_SectionPriority = 1;


    string m_PrefabAssetPath = "Assets/Prefabs/SmallCube.prefab";
    GameObject m_Prefab1;

    static PrefabCreatorBuildingBlock s_Prefab1BuildingBlock;
    const int k_Prefab1BuildingBlockPriority = 10;
    const string k_Prefab1BuildingBlockPath = "GameObject/MySection/" + k_SectionId;

    // We add this Menu Item to the prefab building block here.
    [MenuItem(k_Prefab1BuildingBlockPath, false, k_Prefab1BuildingBlockPriority)]
    public static void ExecuteMenuItem(MenuCommand command) => s_Prefab1BuildingBlock.ExecuteBuildingBlock();

    readonly IBuildingBlock[] m_BBlocksElementIds = new IBuildingBlock[]
    {
        new ScriptedBuildingBlockSample()
    };

    public IEnumerable<IBuildingBlock> GetBuildingBlocks()
    {
        if (string.IsNullOrEmpty(m_PrefabAssetPath))
            return m_BBlocksElementIds;

        //Using the already defined Building Block `PrefabCreatorBuildingBlock` and creating an instance of it with a prefab
        s_Prefab1BuildingBlock = new PrefabCreatorBuildingBlock(m_PrefabAssetPath, "Prefab Creator Block", "an/Icon/Path");

        var elements = m_BBlocksElementIds.ToList();
        elements.Add(s_Prefab1BuildingBlock);
        return elements;
    }
}