7. Sublayer kinds¶
Every sublayer is either on the image bus (it paints cargo) or the mask bus (it decides where cargo shows), and there are three families of them:
7.1 Image-bus kinds¶
Color¶
A solid colour for the channels it targets. The simplest palette. Combine with any mask below it.
Image¶
An image texture. Drag one from Blender's File Browser onto the stack. One sublayer can carry a different image per channel (colour, roughness, normal etc.).
Open Inspector to swap images or change their mapping. Mapping moves them together, Custom Mapping moves one image alone. For placing stuff by hand use the 2D mapping gizmo (chapter 10).
Material¶
Drag a Blender material from Library or the Asset Browser onto the Overpaint panel. It becomes a layer with a Material sublayer, so your compatible material libraries can become painting content too.
- Image textures only: OP uses the textures as channel images.
- Procedural or mixed nodes: OP follows the material's Principled BSDF and uses its channel results (baked when needed).
- Unsupported setup: OP tells you what it could not use. If the material has usable image textures, it can fall back to image mode.
The source material in your library stays as it is. Open the wrench in the inspector to edit the imported node group. Bake to Image turns a procedural into image slots (the group stays available for switching back within the session).
Some limits matter: camera or lighting dependent nodes cannot become a painted texture layer, and not every Principled input is mapped. Read the drop's message for skipped channels. Share an existing Overpaint stack with Create Setup Asset instead of dropping it as a material.
7.2 Mask-bus kinds¶
Fill¶
A constant mask value. A layer with only a Fill below its content shows the content uniformly at the fill's strength; useful as a base for filters or as a global opacity you can animate through the inspector. same usage as Color subayer but in black and white for Mask bus, you can also switch to texture in inspector.
Paint¶
A hand-painted greyscale mask. Painting a Paint sublayer is regular Blender texture painting on a canvas Overpaint creates and manages for you (size, format, colour space and UDIM handling come from OP Settings). White shows the layer's stuff, black hides it.
Procedural¶
A mask produced by a generator node group instead of by hand. The shipped library carries 29:
| Generators | What they give you |
|---|---|
| Dirt, DirtV2 | grime settling into occluded areas, with a floor/wall split; V2 keeps it off convex edges |
| Rust, RustV2 | corrosion creeping out of the crevices; V2 as specks and patches |
| Grunge, GrungeSplotch, GrungeSmudge, GrungeSpeckle, GrungeStreak, GrungeCracked, GrungeConcrete | broken, uneven surface noise in seven flavours; the six variants are tileless 3D noises |
| Gradient, GradientV2 | a directional falloff across the object; V2 adds radial and bottom-up |
| WornEdges, EdgesCavities | worn convex edges protected by AO, with chips; raw edges and cavities |
| Occlusion | the inverted AO, or the inverted thickness |
| Dust | dust settling toward a chosen direction, kept in sheltered spots |
| Scratches | hashed strokes |
| Facing | how strongly the surface faces a chosen direction; needs no bake |
| MaskMix2, MaskMix3 | mixers of edges, cavities and grunge with blend modes |
| P_WornMetal, P_DirtyCrevices, P_DustyTop, P_MossyTop, P_Rusty, P_Scratched, P_OldPaint, P_WetStreaks | ready-made looks: Amount, Scale, Seed and two look controls each |
Generators use helper maps: AO (crevices), Curvature (edges and cavities), Thickness and Edge Detection. In the inspector, use Assign Global for a shared map or Create Local when one layer needs its own (for example, more detail). Position inputs need no bake.
Generators come from the OP Generators asset shelf; click one with a Procedural sublayer selected, or pick it in Paint View. Any node group named generator_… or gen_… in your library appears there too; to write your own, copy a shipped group and change its nodes (chapter 19).
A Procedural sublayer can run live (evaluated by the shader) or be switched to a baked image. Baking runs on the GPU baker and re-runs automatically when you change a generator setting; on a typical 1024² canvas an edit re-bakes in a fraction of a second.