Causes Null Reference in KSP API when model is shared between parts

[Electrocutor]

Example: USI's ORE_DRILL MODEL { model = Squad/Parts/Resources/RadialDrill/TriBitDrill texture = TriBitDrill, UmbraSpaceIndustries/KarbonitePlus/Assets/TriBitDrill_GY scale = 2,2,2 }

The place the exception is being thrown is the KSP API: PartLoader.ReplaceTextures.

Suspect TU cfg: model = Squad/Parts/Resources/RadialDrill/TriBitDrill TEXTURE { shader = SSTU/PBR/Metallic

    texture = _MetallicGlossMap,TexturesUnlimited_Stock/Textures/silver

    excludeMesh = flagTransform
    excludeMesh = Flag
}

[shadowmage45]

Thanks for the report; will be putting this one on the 'priority fix' list as it interferes with stock code in some fashion.

No idea how it could be interfering, but I'll dig into it and find out.

Edit:

• First preliminary idea -- current texture is null for some slots, so when stock tries to replace it, it null-refs from the empty slot (as it tries to use the existing textures name, regardless of if there is actually a texture in that slot).
  • Probably emissive -- could try assigning a black emissive texture to all parts
  • Other channels need to be handled as well
  • Stock code specifically checks '_MainTex', '_BumpMap', and '_Emissive' channels, if any of these are empty/null, it will null-ref.
  • Solution would be to ensure a texture is assigned to these channels, even if it is a tiny placeholder.
  • Code-side solution would be to procedurally create a new placeholder texture for unused channels
  • But then every shader needs a channel map, along with what its default texture color(s) should be

[Electrocutor]

If that is the case, you can use the builtin textures for white and black instead of generating them each time: Texture2D.whiteTexture Texture2D.blackTexture

I also see that Texture2D is where the texture tiling modes are set.

[shadowmage45]

Have a preliminary fix in place that assigns textures to any empty texture slot on any model/mesh that is adjusted through the 'default shader assignments' method.

It has removed the errors from the log when loading stock parts with replaced textures, and am investigating to make sure it hasn't introduced any other problems.

Still had to dynamically create a default Normal Map texture (64x64, flat normals), as Unity doesn't offer a default value for those. Used Texture2D.blackTexture for the placeholder for both DIFF and GLOW slots.