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Lumberyard
User Guide (Version 1.13)

Order-Independent Transparency

Order-independent transparency (OIT) corrects the display of transparent objects that are drawn out of order.

OIT is useful when creating the following:

  • Concave geometry – When you create concave geometry, such as a glass, wine glass, or glass sculpture, some triangles may cover the same pixels and are drawn on top of each other. OIT solves the out-of-order issues that appear from certain angles.

  • Intersecting geometry – When you create intersecting geometry, such as hair planes, some triangles may intersect in separate draws. OIT properly orders the triangles for each pixel.

  • Transparent objects inside transparent objects – This includes liquids inside of glasses, holograms, or x-ray style effects.

To further demonstrate, see the following images.

OIT is not needed in the following example. Drawing object 1, then object 2, and finally object 3 works. OIT is needed in the following example. Drawing object 1 and then object 2 will not work because certain pixels from object 1 must be in front of pixels from object 2 (and vice versa). OIT is needed in the following example. Object 2 is long and its center point is in front of object 1, but it must draw behind object 1. OIT is needed in the following example. Certain parts of object 1 draw behind other parts of the object, and you cannot control which draws first.

Configuring Order-Independent Transparency for Lumberyard

You can configure OIT with the console or create a level configuration file with this setting.

Specify the value for r_AlphaBlendLayerCount to the number of transparency layers that OIT can solve. A value of 1 is sufficient to solve most out-of-order transparency issues.

Valid values: 0 – 4

0 = Disables OIT

  • Specify the value for the r_AlphaBlendLayerCount console variable

  • Specify the value for the level.cfg file in the lumberyard_version\dev\project_name\Levels\level_name directory.

For more information, see Configuring Console Variables.

Note

OIT requires the following:

  • Hardware requirements: DirectX 12_1 feature level compatible graphics card (Nvidia Maxwell & Pascal, 4th generation Intel core processors)

  • Software requirements: DirectX 11.3 and 12 runtime on Windows 10 compiled with Windows 10 SDK