Material painting (PBR)
A painted texture can carry more than colour. Turn on material channels and the Paint brush paints how rough, how metallic, how bumpy and how bright the surface is, all in one stroke, the way game engines and renderers describe materials (physically based rendering, PBR). Every channel lives on the same UVs and paint layers as the colour from Texture painting, and goes out to Unreal, Unity, Godot, Blender, glTF and USD with Export presets.
The channels#
| Channel | What it holds | Stored as |
|---|---|---|
| Base Color | The surface colour. Always there. | 8-bit sRGB (the texture you already paint) |
| Roughness | 0 is mirror-like, 1 fully matte. Starts at 0.65. | 8-bit |
| Metallic | 0 for paint, stone, skin, plastic; 1 for bare metal. Starts at 0. | 8-bit |
| Normal | Fine surface direction, a tangent-space normal map (OpenGL, green up). Starts flat. | 8-bit RGB |
| Height | Painted relief, 0.5 = none. Also adds to the normal ("height to normal"). | 16-bit |
| Ambient Occlusion | How much light reaches crevices, 1 = open. | 8-bit |
| Emissive | Light the surface gives off, black = none. | 8-bit sRGB |
| Opacity | 1 = opaque. Exported in the base colour's alpha. | 8-bit |
A channel you turn on costs no memory until you paint it: channels are stored as 64 x 64 tiles, and a tile nobody painted is not stored at all (a tile of one value is stored as that one value). Turning a channel off discards what was painted in it; Undo brings it back.
Turn channels on#
- Give the SubTool a texture (Texture painting).
- Open Tool > Texture Map. Under Material Channels, tick the channels you want (for a typical game asset: Roughness, Metallic and Normal; add Height to paint relief, Ambient Occlusion to paint dirt into crevices).
- Channel memory below the ticks shows what the painted tiles use; the same number, for every SubTool, is in Preferences > Performance under Memory.
Paint a material#
Open the Color palette. With a material texture, a Material section appears under the swatches:
- Material swatches set the colour, roughness and metallic at once (bare metal, gold, copper, rust, gloss paint, rubber, stone, clay) and make the brush paint those channels.
- One row per channel: the tick says whether the brush paints that channel; the five grey squares pick 0, 25, 50, 75 or 100%; the slider sets any value. Normal has two tilt sliders (0, 0 paints a flat normal). Emissive has a colour.
Untick Base Color to paint only roughness (a wet patch, a polished edge) without touching the colour. Every stroke is one undo step for all the channels it painted. The brush's falloff, alpha, pen pressure, symmetry and mask apply to every channel alike; erasing (Alt) paints Base back to each channel's default and makes layers transparent.
C over the model picks the whole material: the colour and every channel under the cursor become the brush material, and the brush then paints all of the texture's channels.
Layers and channels#
Paint layers (Texture painting) hold every channel. In Tool > Paint Layers, each layer row gets a row of channel chips (BC, R, M, N, H, AO, E, Op):
- Click a chip to turn that channel of the layer on or off. A rust layer can carry colour and roughness but leave metallic alone; a scratches layer can affect only the normal.
-
Right-click a chip for the channel's blend mode and opacity. The ten paint-layer blend modes work per channel (Multiply on roughness halves it where you paint, Screen brightens AO...). The Normal channel adds Normal Combine, which lays the layer's normal detail onto the normals below instead of replacing them. A chip with a
*uses a blend mode other than Normal or less than full opacity. - The layer's own opacity, visibility and lock apply to all its channels.
Merge down and Flatten keep the look of every channel. Duplicate copies a layer with its channels.
See one channel on its own#
Tool > Texture Map > Normal view opens a list: pick Solo Roughness (or any enabled channel) and the model shows just that channel, in grey for roughness, metallic, height, AO and opacity, as colours for the normal (with the height's normal in it) and in colour for emissive. Painting updates it live. Pick Normal view to go back. The viewport doesn't yet render the channels together as a lit PBR material; the solo view is how you check them for now.
Height and normals#
Height is stored with 16 bits, so slow ramps don't band. Its slope becomes a normal that is combined onto the Normal channel (Normal Combine) wherever a normal is shown or exported, so painting height also gives the shading detail. texture_channels height_normal_strength=4 sets how steep that normal is (0: height adds no normal).
Carrying channels through geometry changes#
Auto UV, Voxel Remesh, QRemesh and merging SubTools move every channel and every layer's channels onto the new UVs, as they do the colour. A part without a channel takes that channel's default when SubTools merge.
Projects#
Projects with material channels are saved as format 7 (SculptForge 0.10 and later opens them). A project without material channels is still saved as format 6, so older versions keep opening it. Older projects open as they did.
Commands#
| Command | What it does |
|---|---|
texture_channels enable=roughness,metallic,normal | Turn channels on (disable=... off; no arguments lists them) |
paint_material roughness=0.2 metallic=1 color=c0c0c8 | Set the brush material; channels=all / channels=roughness say exactly what it paints |
texture_layer_channel channel=normal blend=normal_combine | A layer's channel settings (enabled, blend, opacity; layer or index) |
channel_view channel=roughness | Solo a channel in the viewport (off to go back) |
export_maps preset=unreal folder=... | Write the maps (Export presets) |
Limitations#
- The viewport shows one channel at a time (solo view); a lit PBR preview with environment lighting is planned.
- Fill layers, generators (edge wear, dirt), mesh-map bakes as layer inputs, filters and material recipes are planned; today the stack is paint layers.
- One texture per SubTool (no UDIM tiles yet).
- Memory: colour, roughness, metallic, height and AO on Base plus three layers, each with a few big strokes, take about 370 MB at 4K and 1.5 GB at 8K (most of it the colour layers); a layer painted everywhere adds about 200 MB of channels at 4K and 800 MB at 8K. Preferences > Performance shows the numbers for your scene. Paint at 4K unless you need 8K.
- Export Maps takes a few seconds at 4K and about ten at 8K (PNG compression).