Developer Notes

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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 - Graphics Features
Affects Versions4.7.34.84.14
CreatedMar 31, 2015
ResolvedFeb 21, 2017
UpdatedApr 27, 2018
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