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Can anyone explain what post process inputs 1-6 do?

Can anyone explain what post process inputs 1-6 do? Input 0 is obvious but the others are not. Can anyone shed light on this or provide a link? I cant seem to find what I’m looking for in the UE4 documentation. The closest thing i can find is https://docs.unrealengine.com/en-US/Engine/Rendering/PostProcessEffects/PostProcessMaterials which talks a bit about 1 and 2.

Based on the UE source code: https://github.com/EpicGames/UnrealE…Material.h#L20 (Accurate as of 4.24)


/** Named post process material slots. Inputs are aliased and have different semantics
* based on the post process material blend point, which is documented with the input.
*/
enum class EPostProcessMaterialInput : uint32
{
// Always Active. Color from the previous stage of the post process chain.
SceneColor = 0,

// Always Active.
SeparateTranslucency = 1,

// Replace Tonemap Only. Half resolution combined bloom input.
CombinedBloom = 2,

// Buffer Visualization Only.
PreTonemapHDRColor = 2,
PostTonemapHDRColor = 3,

// Active if separate velocity pass is used--i.e. not part of base pass; Not active during Replace Tonemap.
Velocity = 4
};

You can see that the Input Buffers are used differently based on which PP chain in https://github.com/EpicGames/UnrealE…Processing.cpp