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Unreal Engine 4.14 Is an Awesome Update for VR

31st December 2016 - By 
Unreal Engine 4.14 Released! - Luxxlabs

This release includes hundreds of updates from Epic and 71 improvements submitted by the incredible community of Unreal Engine developers on GitHub!

What’s New

Unreal Engine 4.14 introduces a new forward shading renderer optimized for VR, enabling crisp multi-sampled anti-aliasing in your games. The new Contact Shadows feature renders beautifully detailed shadows for intricate objects. We’ve also introduced a new automatic LOD generation feature for static meshes that does not require a third-party library.

We’ve streamlined the animation tools to help you be more productive, and added many new features to Sequencer (UE4’s non-linear cinematic tool), as well as improvements to vehicles, clothing and animation Blueprints.

For mobile developers, Vulkan support is ready to use on compatible Android devices! And, we’ve added various new mobile rendering features such as reading from scene color and depth, and the ability to draw 3D objects on top of your UI.

On the Windows platform, C++ programmers can now use Visual Studio “15” for development. Visual Studio 2015 is still supported.

Major Features

New: Forward Shading Renderer with MSAA

The new forward shading renderer combines high-quality UE4 lighting features with Multisample Anti-Aliasing (MSAA) support! MSAA and the option to enable per-material optimizations make the forward renderer well suited for VR.

Unreal Engine 4.14 Released! - Luxxlabs

The forward renderer works by culling lights and reflection captures to a frustum-space grid. Each pixel in the forward pass then iterates over the lights and reflection captures affecting it, shading the material with them. Dynamic shadows for stationary lights are computed beforehand and packed into channels of a screen-space shadow mask allowing multiple shadowing features to be used efficiently. Enable ‘Forward Shading’ in the Rendering Project settings and restart the editor to use the forward renderer.

Supported forward rendering features include:

  • Full support for stationary lights, including dynamic shadows from movable objects which blend together with precomputed environment shadows
  • Multiple reflection captures blended together with parallax correction
  • Planar reflections of a partial scene, composited into reflection captures
  • D-Buffer decals
  • Precomputed lighting and skylights
  • Unshadowed movable lights
  • Capsule shadows
  • Instanced stereo compatible

Some features are not yet supported with Forward Shading:

  • Screen space techniques (SSR, SSAO, Contact Shadows)
  • Shadow casting Movable Lights
  • Dynamically shadowed translucency
  • Translucency receiving environment shadows from a stationary light
  • Light functions and IES profiles
  • Alpha to Coverage
  • MSAA on D-Buffer decals, motion blur, dynamic shadows and capsule shadows

Unreal Engine 4.14 Released! - Luxxlabs

The forward renderer supports both multi sample anti-aliasing (MSAA) and temporal anti-aliasing (TAA). In most cases TAA is preferable because it removes both geometric aliasing and specular aliasing. In VR, the constant sub-pixel movement introduced by head tracking introduces unwanted blurriness, making MSAA a better choice.

Projects that choose to use MSAA will want to build content to mitigate specular aliasing. The ‘Normal to Roughness’ feature can help reduce specular aliasing from detailed normal maps. Automatic LOD generation for static meshes can flatten features on distant meshes and help reduce aliasing from small triangles.

In our tests, using MSAA instead of TAA increases GPU frame time by about 25%. Actual cost will depend on your content.

To use MSAA, set the default Anti-Aliasing Method in the Rendering project settings:

The console variable ‘r.MSAACount’ controls how many MSAA samples are computed for every pixel. ‘r.MSAACount 1’ has special meaning and falls back to Temporal AA, which allows for convenient toggling between anti-aliasing methods.

Performance

The forward renderer can be faster than the deferred renderer for some content. Most of the performance improvement comes from features that can be disabled per material. By default, only the nearest reflection capture will be applied without parallax correction unless the material opts-in to High Quality Reflections, height fog is computed per-vertex, and planar reflections are only applied to materials that enable it.

Leveraging these options in Epic’s new VR game, Robo Recall, the forward renderer is about 22% faster than the deferred renderer on an NVIDIA 970 GTX.

New: Contact Shadows

Contact shadows allow for highly detailed dynamic shadows on objects.

The ivy below is only a few flat cards but is able to self-shadow in a very convincing way due to outputting Pixel Depth Offset in the material.

The Contact Shadows feature adds a short ray cast in screen space against the depth buffer to know whether a pixel is occluded from a given light or not. This helps provide sharp detailed shadows at the contact point of geometry. There are a number of reasons why shadows through other algorithms may have missing or blurry contacts. Typically it is due to lack of resolution or a depth bias. Regardless of the reason, the new Contact Shadows feature can fill in the gap very well for a small cost.

Contact shadows can be used by setting the Contact Shadow Length property on your light. This controls the length of the ray cast in screen space where 1 is all the way across the screen. Large values can degrade quality and performance so try and keep the length to the minimum that achieves your desired look.

Another use case of contact shadows is to get self-shadowing from the parallax occlusion mapping from arbitrary lights. This requires outputting pixel depth offset in the material. This animation shows a parallax occlusion mapped surface with contact shadow length set to 0.1.

Further Reading

There is much, much more in this update, so definitely dig into the full release information below.

Unreal Engine 4.14 Released!
As always, Epic provides a solid overview, a detailed breakdown, and comprehensive release notes of all the changes in 4.14.

NVIDIA Ansel Technology Page
NVIDIA overview of the Ansel features and capabilities.

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