# The Shadow Problem of Nanite Mesh Using WPO Materials

**URL:** <https://forums.unrealengine.com/t/the-shadow-problem-of-nanite-mesh-using-wpo-materials/1326765>\
**Category:** Rendering\
**Tags:** world-position-offse, unreal-engine, Nanite, question\
**Created:** [October 9, 2023, 3:28am UTC](https://forums.unrealengine.com/t/the-shadow-problem-of-nanite-mesh-using-wpo-materials/1326765 "2023-10-09T03:28:59Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Anonymous\_33fa8cc5ffe4885a94ac8481b4179e36](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Anonymous\_33fa8cc5ffe4885a94ac8481b4179e36](https://forums.unrealengine.com/u/Anonymous_33fa8cc5ffe4885a94ac8481b4179e36)\
**Post date:** [October 9, 2023, 3:28am UTC](https://forums.unrealengine.com/t/the-shadow-problem-of-nanite-mesh-using-wpo-materials/1326765/1 "2023-10-09T03:28:59Z")

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The following are the effects of the two solutions I have tried  
Option A: Use nanite mesh+lumen+hardware light tracing  
As shown in the figure : The shadow calculated by hardware light tracing is based on Nanite fallback mesh

 ![微信截图_20231009111424](https://d3kjluh73b9h9o.cloudfront.net/original/4X/f/a/6/fa68079a10fba058ee7f1666d6124c2010554944.jpeg)  
Option B: Use nanite mesh+lumen+distance field of mesh  
As shown in the figure: The red box shows the shadow before the wpo of some triangular faces, while the blue box shows the shadow after the wpo of some triangular faces  
 ![微信截图_20231009112038](https://d3kjluh73b9h9o.cloudfront.net/original/4X/1/d/4/1d4c02e8a28eb7f3ef876abad6ec10b684157b6b.jpeg)  
I want the shadow to match the mesh after the WPO, so I hope everyone can help me. Thanks

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**Author:** ![ZacD](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@ZacD](https://forums.unrealengine.com/u/ZacD)\
**Post date:** [October 9, 2023, 11:26am UTC](https://forums.unrealengine.com/t/the-shadow-problem-of-nanite-mesh-using-wpo-materials/1326765/2 "2023-10-09T11:26:07Z")

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If you’re using VSM, you need the bounds of the static mesh to extend to contain anywhere the mesh can move to using WPO

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**Author:** ![Anonymous\_33fa8cc5ffe4885a94ac8481b4179e36](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Anonymous\_33fa8cc5ffe4885a94ac8481b4179e36](https://forums.unrealengine.com/u/Anonymous_33fa8cc5ffe4885a94ac8481b4179e36)\
**Post date:** [October 10, 2023, 1:17am UTC](https://forums.unrealengine.com/t/the-shadow-problem-of-nanite-mesh-using-wpo-materials/1326765/3 "2023-10-10T01:17:09Z")

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Yes, I used VSM, and I also expanded the bound of the static mesh, but the problem did not disappear. Below is my VSM cache page and bound

 ![微信截图_20231010091004](https://d3kjluh73b9h9o.cloudfront.net/original/4X/3/a/7/3a7f80ed62f94cfa20e9b0462402738b0d5d7295.jpeg)  
 ![微信截图_20231010091456](https://d3kjluh73b9h9o.cloudfront.net/original/4X/1/d/6/1d6790e1d1719e780ec5e9f60af56600c97b7c1c.jpeg)