Description

Incorrect collision of merged actor that was merged from a Spline Mesh Component

Licensee description:

We often use spline mesh blueprints to generate organic art for us, like roots, trees, and rope bridges. To reduce the rendering costs of these blueprints, we run merge actors against groups of them. When we These BP's get merged with the Merge Physics Data open enabled, we have notice that the collision is not correctly distributed along the spline mesh. Each render mesh segment is in its correct location and correct start and end spline point tangent locations. However each collision sits at the pivot of the spline mesh BP in its default orientation.

This has left us using the complex render mesh as collision, which is obviously not desirable.

When merging actors we are using the default options Pivot Point at Zero = true Merge Physics Data = true Bake Vertex Data to Mesh = true LODSelection = All

Attached we have to images to show the before and after results. In the over results we have by hand moved two of the collision surfaces to verify that there were multiple collision prims stacked on top of each other.

Steps to Reproduce

1. Open the attached test project
2. In the Viewport > Show > Make sure Show Collision is enabled
3. Select the spline mesh actor in the level
4. Window > Developer Tools > Merge Actors
5. Make sure 'Merge Physics Data' is enabled > Press 'Merge Actors' > Save
6. Back in the editor, place the new static mesh into the level

Results: All of the separate collisions have been stacked at the 0,0,0 on the merged actor

Expected: For all of the spline mesh components to keep their collisions in place in the new merged actor

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There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-43837 in the post.

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Fixed
ComponentUE - Simulation - Physics
Affects Versions4.14.34.15.14.16
Target Fix4.17
Fix Commit3489235
Main Commit3502661
CreatedApr 10, 2017
ResolvedJun 14, 2017
UpdatedApr 27, 2018
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