Unreal Engine Issues

UE-16704

Scalar Parameter versus Constant placed in Alpha of LERP produces inconsistent results in Blendable

Scalar Parameter versus Constant placed in Alpha of LERP produces inconsistent results in Blendable

Developer Notes

This issue has been closed as 'Won't Fix' due to an extended period of time without updates. If this issue is important to you please let us know by posting on the AnswerHub or UDN, and Epic will re-open the ticket for further review.

Questions & Answers
Description

When placing a Scalar Parameter into the Alpha position of a LERP you will not get the same results as placing a Constant Value when used in a Post Process Material.

Constant Value of 0:
[Image Removed]

Constant Value of 1:
[Image Removed]

Scalar Value of 0:
[Image Removed]

Scalar Value of 1:
[Image Removed]

Also Reproduced in Main Promotable-CL-2579896 & Releases/4.8/Promoted-CL-2573784

Steps to Reproduce
  1. Open QAGame Editor
  2. Recreate Post Process Material Pictured Above
  3. Assign Material to Unbound Post Process Volume in Level
  4. Plug in a Constant 1 into Alpha of LERP in Post Process Material.
  5. Plug in a Scalar Parameter 1 into Alpha of LERP in Post Process Material.

RESULTS: Blendable Material does not look the same when using a Scalar and a Constant

EXPECTED: The Blendable should produce the same results no matter a Scalar or a Constant.

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Won't Fix
ComponentUE - Graphics Features
Affects Versions4.7.6, 4.8, 4.9, 4.14
CreatedJun 8, 2015
ResolvedMar 1, 2017
UpdatedApr 27, 2018
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