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.

Description

The Noise Material Expression is rendering values well outside the Min and Max Range set in the Expression node.

Also Reproduced in Main Promotable-CL-2469752

Alerted the user to suspicions and suggestions as discussed in email (see below for reference) and user is reporting that the using the same high value position in a Custom node with an input called EvalPos and with the code

 return SimplexNoise3D_TEX(EvalPos); 

you will get results that are correctly between -1 and 1 (Tested and confirmed in Main)

===from email conversation, for reference only===
"I wasn't aware of this but it might be because of multiple floating point operations result in a very low precision result. e.g.
1000000.2 - 1000000.1 in float is not exactly 0.1.

Some methods use texture interpolation hardware which is even less precise.

I suggest to try the different nose methods, reduce the input number range (frac, relative to object center, scale down, ...)
or clamp the result.

There might be a bug but I wouldn't be surprised if large numbers can cause issues.

The methods have different properties but none is perfect - maybe we can improve on that issue.

I assume the min and max in the noise expression are set to the defaults.

Martin"

Steps to Reproduce
  1. Open QAGame Editor
  2. Create a New Material
  3. Add a Noise Node (leave with default settings)
  4. Add a Vector3 (362,23343,4325) connected into Position
  5. Pass the Noise through a Debug Scalar Values Material Function
  6. Pull the Result of the Debug node into Emissive Color

RESULTS: value of 3.## showing

EXPECTED: a value between 1 and -1

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Won't Fix
ComponentUE - Rendering
Affects Versions4.7.34.84.14
CreatedMar 31, 2015
ResolvedFeb 21, 2017
UpdatedApr 27, 2018