The video below shows Skeletal Mesh components representing the individual states and additionally instances used for blending between states. It also shows the crowd, which are all individual actors for which an Animation State is determined. According to the Animation State the Skeletal Mesh Components are connected to the Master Components for driving their Animation. In the video only the Poses for the Animation States are evaluated, the Crowd Actors only copy the resulting bone transforms.

New: Support for long filenames (Experimental)

We added support for long file paths for users with Windows 10 Anniversary Update! Historically, paths in windows have been limited to 260 characters, which can cause problems for projects with complex naming conventions and deep hierarchies of assets. The Windows 10 Anniversary Update adds support for much longer filenames, on the condition that the user and each application opt-in to it. To enable long file paths in Windows 10:

• Ensure you're running Windows 10 version 1607 or later
• Enable support for long paths via the group policy setting or registry (see https://docs.microsoft.com/en-us/windows/desktop/FileIO/naming-a-file#maxpath[/url])
• In the Unreal Editor, check the "Enable Long Paths Support" in the experimental settings dialog.

Note: Support for long paths is not universal, and third party tools - even parts of the operating system, like Windows Explorer - may not support them correctly.

New: Blueprint Indexing Optimizations

Changes to how we index Blueprint search data have significantly improved Editor and Play-In-Editor startup times. We now defer search data updates until a Find-in-Blueprint tab is opened, perform updates asynchronously, and separate Blueprint re-indexing from the Asset loading process.

New: Improved Steamworks support

Using UE4 with Steam has never been easier! We've made several improvements to usability and quality of life for developers of multiplayer games on Steam.

• Dedicated Servers on Steam can now receive custom names (up to 63 characters) with the new "-SteamServerName" launch argument.
• Projects can now override the Steam network layer by deactivating the "bUseSteamNetworking" configuration value and setting their NetDriver configurations to the preferred underlying network layer.
• We have greatly improved the usability of Steam NetDrivers with UE4 Beacons in addition to standard game networking.
• You can now set certain required Steam values, such as dedicated server names, or the application ID, in your project's Target.cs file. Making changes to these values will no longer require recompiling the engine.

New: Preview Scene Settings Improvements

We added functionality to Preview Scene Settings that enables you to hide Environment Cubemap (Show Environment]) without disabling lighting. See the Use Sky Lighting property in the Preview Scene Settings panel. 

New: Skeletal Mesh LOD Reduction

Use the Skeletal Mesh Reduction Tool to generate versions of a Skeletal Mesh with reduced complexity for use as levels of detail (LODs) all within Unreal Editor! You no longer need to rely on external Digital Content Creation (DCC) programs or third party tools that can be very time consuming and error prone. Create accurate, high-quality levels of detail and see the results immediately in the viewport.

For additional information, see Skeletal Mesh Reduction Tool.

New: Per Platform Properties Improvements

Per Platform Properties have been extended to allow for setting values based on Target Platform in addition to the Platform Groups.

New: Gauntlet Automation Framework Improvements

The Gauntlet automation framework received several improvements focusing on usability, documentation, and examples to learn from.

Expanded documentation & samples

• Documentation about Gauntlet architecture and getting started
• Additional ActionRPG and Profile Guided Optimization examples
• Example of tracking editor load and PIE times

iOS Support

Gauntlet now supports installing and running IPA files on iOS (requires Mac host). This takes our device support to PC, Mac, PS4, XB1, Switch, Android, and iOS.

Profile Guided Optimization

An example script for automation of  Profile Guided Optimization (PGO) file generation on PS4, XboxOne, and Switch for your project. 

Report Creation

Added HTML and Markdown builders for creating custom reports as part of automation scripts.

New: Visual Studio 2019 Support

Support for Visual Studio 2019 has been added. To use Visual Studio 2019 by default, select "Visual Studio 2019" as the IDE from the editor's source control settings.

We've also added support for switching to newer C++ standard versions. To change the version of the C++ standard that your project supports, set the CppStandard property to one of the following values from your .target.cs file.

Version	Value
C++14	CppStandardVersion.Cpp14
C++17	CppStandardVersion.Cpp17
Latest	CppStandardVersion.Latest

At the same time, we've deprecated support for Visual Studio 2015. If you want to force your project to compile with the Visual Studio 2015 compiler, you can set WindowsPlatform.Compiler = WindowsCompiler.VisualStudio2015 from your project's .target.cs file. Note that the version of the engine downloaded from the Epic Games Launcher does not support Visual Studio 2015, and we no longer test it internally. 

New: Subsystems

Subsystems are automatically instanced classes with managed lifetimes which provide easy to use extension points without the complexity of modifying or overriding engine classes, while simultaneously getting Blueprint and Python exposure out of the box.

Currently Supported Subsystem Lifetimes

Engine

class UMyEngineSubsystem : public UEngineSubsystem { ... };

When the Engine Subsystem's module loads, the subsystem will Initialize() after the module's Startup() function has returned. The subsystem will Deinitialize() after the module's Shutdown() function has returned.

These subsystems are accessed through GEngine:

UMyEngineSubsystem MySubsystem = GEngine->GetEngineSubsystem();

Editor

class UMyEditorSubsystem : public UEditorSubsystem { ... };

When the Editor Subsystem's module loads, the subsystem will Initialize() after the module's Startup() function has returned. The subsystem will Deinitialize() after the module's Shutdown() function has returned.

These subsystems are accessed through GEditor:

UMyEditorSubsystem MySubsystem = GEditor->GetEditorSubsystem();

Note: These Editor Only subsystems are not accessible to regular Blueprints, they are only accessible to Editor Utility Widgets and Blutility Classes.

GameInstance

class UMyGameSubsystem : public UGameInstanceSubsystem { ... };M

This can be accessed through UGameInstance:

UGameInstance* GameInstance = ...;
UMyGameSubsystem* MySubsystem = GameInstance->GetSubsystem();

LocalPlayer

class UMyPlayerSubsystem : public ULocalPlayerSubsystem { ... };

This can be accessed through ULocalPlayer:

ULocalPlayer* LocalPlayer = ...;
UMyPlayerSubsystem * MySubsystem = LocalPlayer->GetSubsystem();

Accessing Subsystems from Blueprints
Subsystems are automatically exposed to Blueprints, with smart nodes that understand context and don't require casting.

You're in control of what API is available to Blueprints with the standard UFUNCTION() markup and rules. Subsystems from Python
If you are using Python to script the editor, you can use built-in accessors to get at subsystems:

my_engine_subsystem = unreal.get_engine_subsystem(unreal.MyEngineSubsystem)
my_editor_subsystem = unreal.get_editor_subsystem(unreal.MyEditorSubsystem)

Note: Python is currently an experimental feature.

New: Editor Utility Widgets

Editor Utility Widgets enable you to extend the functionality of Unreal Editor with new user interfaces created entirely using the UMG UI Editor and Blueprint Visual Scripting logic! These are Editor-only UI panels that can be selected from the Windows menu like other Unreal Editor panels. To create an Editor Utility Widget, right-click in the Content Browser and select Editor Utilities > Editor Widget.

To edit the Blueprint, double-click on the Editor Widget Asset. Once you've edited the Blueprint for your Editor Widget Asset, right-click the Editor Widget and select Run Editor Utility Widget to open the UI in a tab. The tab is only dockable with Level Editor tabs. It appears in the Level Editor's Windows dropdown, under the Editor Utility Widgets category. This is an experimental feature. 

New: Material Analyzer

The Material Analyzer enables you to get a holistic view of parameter usage in Materials and Material Instances so you can quickly find opportunities to consolidate and optimize your Material Instances to minimize switching render state and save memory. The Material Analyzer can be found under Window > Developer Tools. Materials are listed in a tree with a list of suggestions which show groups of material instances with the same set of static overrides so you can make optimizations. You can also place all the related instances into a local collection, so you can easily find and update them.  

New: Select Child and Descendant Actors

You can now extend your selection to all the immediate children or all the descendants of your selected Actor using the context menu in the World Outliner and the Level Viewport, making it easier to work with large, complex scene hierarchies.

New: Scaled Camera Zoom and Pan

When you have one or more objects selected in the Level Viewport, the sensitivity of camera zoom and pan operations now scales automatically with the distance between the objects and the camera. This makes your camera movements feel more natural, especially when you're working with objects at extreme sizes, such as tiny mechanical parts or large landscapes.

You can return to the previous behavior by disabling the new Use distance-scaled camera speed setting in the Level Editor > Viewports section of the Editor Preferences window. 

New: Orbit Around Selection

You can now make the camera orbit around the pivot of the selected objects - as opposed to orbiting around the center of the screen - when one or more objects are selected in the Level Viewport. To activate this mode, enable the new Orbit camera around selection setting in the Level Editor > Viewports section of the Editor Preferences window. 

New: Toggle Multiple Layer Visibility

You can now toggle the visibility of multiple Layers at the same time. Hold CTRL and click each Layer to build your selection. Then click the eye icon next to any of those selected Layers to toggle visibility of all selected Layers.