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PreparePerturbNormalHQ Usage

Greetings,

In lieu of having Derivative map support I’ve been trying to use the following documentation to get single-channel bump maps working:

https://docs.unrealengine.com/latest/INT/Engine/Rendering/LightingAndShadows/BumpMappingWithoutTangentSpace/index.html

(I have a use case that really needs to be able to pack at least 2 input maps providing bump data into a single sampler)

That said I really don’t understand the PreparePerturbNormalHQ function. Using the right/down/center texel cross as input to PerturbNormalHQ makes sense, but the example shows PreparePerturbNormalHQ taking Actor Position as a V3 input.

The docs describe the input as “The scalar bump value (grayscale) at the current position.”

What is intended to be used for this input? Does anyone have any use-cases they could share?

Thanks!

In search of the same exact question I found this solution:
https://answers.unrealengine.com/questions/198047/generate-normal-from-noise-imposible.html