Surface Sculpt

Overview

The node for hand-correcting generated volume. It layers brush edits — raise / carve / smooth / always-dark — on top of the height and AO that layers_to_surface (or any Surface source) estimated. Corrections are stored in the cause space (height and AO), not in the shading result, so they keep following correctly when the light moves or the art animates.

Usage tips

• The standard chain: layers_to_surface → surface_sculpt → surface_light_preview. Insert it right after shape generation, upstream of any move / deform / animation. Downstream path_deform carries the maps along, so sculpted height travels with the part.
• Double-click the node (or use the inspector's "Sculpt Surface" button) to open the editor. The preview always shows the lit, stepped result, so you sculpt while watching how the shading actually changes.
• Six brushes: Raise (build up), Carve (dig in), Smooth (average out noise — slopes are preserved), Level (pull heights to where the stroke started — use this, not Smooth, to actually flatten), Always dark (paint light-independent darkness into AO — grooves, contact, the inside of a mouth), and Region raise (click to outline a region, close it, then click the summit: builds a whole mound rising from the border to the summit, with a Round / Sharp / Flat cross-section. Place summit points and re-click the same point to confirm: 1 point = a pointed peak, 2 = a ridge line, 3+ closed via the first point = a plateau - sword ridges and mesa-like hills in one go. A hint following the cursor guides each step).
• Alt+click locks sculpting to one part (face id): locked strokes only affect that layer's pixels, so you can paint near part borders without bleeding onto neighbours.
• Bake flattens the strokes so far into delta maps, keeping evaluation fast no matter how many strokes pile up. Baked edits can't be undone individually (confirmed first); later strokes stack on top.
• The angle / elevation knobs in the toolbar are a working light only. They never affect the node's output; the final light belongs to the downstream surface_light_preview.
• Switch to 3D to check the actual relief: drag to orbit, and toggle the texture between stepped preview and albedo. Sculpt in 2D, verify the form in 3D.
• Strokes are stored on the node, so .ppl distribution, copy-paste, and variant capture all work. Redrawing the upstream art re-applies the same strokes at the same coordinates.

Common pitfalls

• The editor stays on "waiting for evaluation": the upstream surface has not been evaluated yet. Select the node, let evaluation finish, and reopen.
• Sculpted but the downstream look does not change: the editor's light knobs are the working light, separate from the downstream surface_light_preview settings. Tiny height differences can also be quantized into the same shading step — raise the strength or stroke the same spot again.
• Corrections drift during animation: the sculpt node sits downstream of a deformer. Move it back to right after shape generation (rest pose).

Related nodes

• layers_to_surface — assembles the surface the sculpt starts from
• surface_light_preview — lights and steps the sculpted result
• quick_shade — quick single-image surface (its output can be sculpted too)
• surface_id_mask — extract per-layer masks from face ids