Custom mesh normals cause glowing/shining artifacts from certain angles

Reproduction Steps

Import mesh that has custom normals that face away from their original plane normal significantly.

look at the mesh at an angle such the mesh is between the camera and the sun

System Information:
AMD Ryzen 3 2200G, 16GB, Radeon RX 570

Expected Behavior

I expect my mesh to have rounded normals and respond to light correctly

Actual Behavior

the normals that are facing towards the sun start to glow from what i assume is an “unclamped” shining effect
this is further amplified using pbr materials that have higher roughness (which should be doing the opposite effect of dampening the gloss on the object)

demonstration:

tree normals viewed in blender, represented by the purple vectors

blender file of mesh:
tree custom normals.blend (3.5 MB)

imported model:
tree custom normals imported.rbxm (4.3 KB)

this issue happens to most tree meshes that use a similar normal transfer technique in other live games as well
another model i noticed this issue on was the forest pack officially released by roblox

Issue Area: Engine
Issue Type: Display
Impact: High
Frequency: Constantlyi

16 Likes

+1

I’ve seen this same effect for objects with their normals all set to one direction, as well. eg: Vector3(0,1,0)

4 Likes

image

This is also happening to me.

1 Like

Thanks for the report! We’ll follow up when we have an update for you.

3 Likes

Could we get an update for this request? It’s almost been a year now and It’s still affecting every single game that uses foliage with modified normals, even the big front page ones, It’s been a major roadblock for my environments and I’m sure many other artists as well

1 Like

Happens with editable meshes too!

3 Likes

As a different pov, some UGC accessories appear to use this bug to create cool lighting effects on their accessories, so fixing this issue without a toggle of some form (or legacy support) would unfortunately break such UGC accessories.

1 Like

oh, I’m curious which accessories use it and in what way, mind linking me some? I can’t imagine any cool effects that could be achieved with this