[UE4]Performance Guidelines for Mobile Devices

keywords: [UE4]Performance Guidelines for Mobile Devices

keywords: Mobile Performance Optimization, Official Documents

Materials

Use Full Precision
The Material Editor contains a section called Mobile, which has two properties: Use Full Precision and Use Lightmap Directionality. These are intended for mobile devices and to save performance. By default, Unreal will use less-precise math in order to save on memory and computation time. When enabled, the Use Full Precision property will use the highest precision available on a mobile device. This will solve certain rendering issues at the cost of being more expensive to use. Generally, you’ll leave this property disabled unless you notice issues with how the material looks.
Use Lightmap Directionality
Use Lightmap Directionality, has an effect that is very apparent when using a normal map. Basically, it will use the lightmap to show the light at the top of the normal map and shadows at the bottom. You’ll need to Build the project in order to see the lightmap information being used. If disabled, lighting from lightmaps will be flat but cheaper.
Fully Rough
The Material section contains the Fully Rough property that, when enabled, will ignore the Roughness channel and instead force the material to be completely rough. This will save a number of instructions for optimization’s sake and reduce one texture sampler.
High Quality Reflections
The Forward Shading section contains the High Quality Reflections property which, when disabled, can increase the number of texture samples you can use by two. Turning this off will remove them to instead be used for cubemaps to display reflections.

While some of these properties will have less quality than the traditional fully-formed material, the settings can reduce the number of instructions on the vertex shader and the Texture samplers used, which you can see from the Stats toolbar from the Material Editor.

Quoted from [Unreal Engine 4 Shaders and Effects Cookbook] Chapter 8 Mobile Shaders and Material Optimization
https://www.packtpub.com/game-development/unreal-engine-4-shaders-and-effects-cookbook

LOD

1, Dithered LOD Transitions support on Mobile, but it would increase rendering overhead.

Rendering

1, Disable HDR on mobile if frame rate is low, otherwise image would be blur when camera transforming. But Lighting effect would lose violently if HRD disabled.

Reference

如何改善虚幻引擎中的游戏线程CPU性能表现
https://www.unrealengine.com/zh-CN/blog/how-to-improve-game-thread-cpu-performance

UE4 性能优化方法(工具篇)
https://www.cnblogs.com/ghl_carmack/p/5481763.html

Bringing AAA graphics to mobile platforms
https://twvideo01.ubm-us.net/o1/vault/gdc2012/slides/Programming%20Track/Smedberg_Niklas_Bringing_AAA_Graphics.pdf

Offical Docs

人生中有些事是不得不做的，于不得不做中勉强去做，是毁灭；于不得不做中做的好，是勇敢。——叶弥《成长如蜕》

[UE4]Performance Guidelines for Mobile Devices

Materials

LOD

Rendering

Reference

Offical Docs

Mobile Game Development

Materials on Mobile

Performance on Mobile

Wang Aiguo