Description

When using PerInstanceRandom in a material that is applied to a Hierarchical or normal Instanced Static Mesh component, there are issues of the value resetting when certain transform operations are performed.

For Hierarchical Instanced Static Meshes, if the component itself is rotated, the PerInstanceRandom of each instance is reset (Seen in the reproduction project via the bottom row of cubes)

For Hierarchical and normal Instanced Static Meshes, if the individual instances have their transform modified, their PerInstanceRandom values will be reset. (Seen in the reproduction project via the top row of cubes)

Regression?: No
This does not occur in 4.16, but that is likely due to the base functionality being broken and fixed here: [Link Removed]

Steps to Reproduce
  1. Download the attached project
  2. Press play
    Result: The cubes on the bottom (Hierarchical Instanced Static Mesh) have their PerInstanceRandom reset when the component is rotated. The cube on the right of the set on the top (Instanced Static Mesh) has its PerInstanceRandom reset when its individual transform is changed
    Expected: None of the PerInstanceRandom values are reset during these transform operations

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Fixed
ComponentUE - Graphics Features
Affects Versions4.17.24.184.19
Target Fix4.19
Fix Commit3744860
Main Commit3807911
Release Commit3858364
CreatedNov 6, 2017
ResolvedNov 8, 2017
UpdatedMay 4, 2018