problem getting double-sided normals to display

Unity Engine
1

We’re having trouble with some Maya character models: Certain polygons (collars and bonnets) need to have double-sided normals so both sides are visible in the game. The 3D artist (who doesn’t have Unity) has those faces set properly in Maya, but after import to Unity, they are one-sided; the backside is transparent. Is there a trick in Maya or Unity to assigning double-sided normals to certain faces (we don’t want to make the entire mesh double-sided, obviously).

The 3D artist also noted, looking at the Unity build, that smooth groups are not properly exported to Unity as well as they are set up in Maya (in case that’s a related issue).

thanks
Dave

2

you need to create a 2 sided face, flip the back one then import to unity

I think,

Ray

3

The 3D-artist should just make a copy of the relevant faces, and then flip the normals, so you got two triangles for each triangle, in those areas. Pointing opposite direction…
You can also make special shaders which renders both sides of a triangle, but the first solution would be the easiest. I’m not sure which one is the best, memory wise… :sweat_smile:
As for you other problem with normals not importing properly, just check the settings dialog in the project view, and make sure to uncheck the “Automatically calculate normals”… This has to be done per object, it’s NOT a global setting.

4

To render 2-sided materials, add “Cull Off” to the Category block of the shader file of your choice (I used Transparent/Diffuse).

Ideally only assign this to objects inside your model that needs 2-sided rendering and not the whole 3d model

5

Cull off for shaders is one solution. Just be aware though that this breaks lighting rather badly due to the normals still only really pointing in one direction.