Developer Notes

This is part of a deliberate change that will be called out in the Major Release Notes for 4.15 with more information.

We now use the default value of 1 for r.TonemapperFilm instead of 0. To get the old color emissive back you'll need to change the CVar back to 0.


When multiplying vector 3 (R,G,B) values by a scalar value of increasing quantity the emissive output will begin to change colors. The most unexpected is the blue color that will turn purple while the bloom remains blue.

The color turning white while being multiplied by larger values seems intentional however, there is no documentation to be found even in our internal 4.15 release notes regarding this behavior.


Worked: Binary 4.14.3 CL 3249277
Broken: Binary 4.15 Preview 1 CL 3258144

Steps to Reproduce
  1. Create a new blank project
  2. Create material and add a vector 3 node with the values (0,0,1)
  3. Multiply the vector 3 by a scalar parameter (plug into emissive)
  4. Compile and apply the material to a mesh in the scene
  5. Start increasing the scalar param to about a value of 10

The mesh will start blue then fade to purple if you continue it will turn white.

The mesh stays blue with increased bloom as the emissive gets multiplied by larger values.

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By Design
ComponentUE - Rendering
Affects Versions4.15
Target Fix4.15
CreatedJan 24, 2017
ResolvedJan 30, 2017
UpdatedApr 27, 2018