blender

# blender Blender runs here as a Python module (`bpy`, pinned): everything Blender does, no window. Scripts live in `scenes/`, run with `$BLENDER_PYTHON`, and `harness_blender` (on `PYTHONPATH`) gives you the scene, the camera, the export, the renders and the report in one import. ## Build, export, render, verdict ```bash "$BLENDER_PYTHON" scenes/hello.py # builds → out/model.glb, out/preview.png, out/turntable.mp4, out/report.json "$BLENDER_PYTHON" "$BLENDER_TOOLCHAIN/verdict.py" # judges out/ → the pane header, and which glTF the pane opens ``` ```python import bpy from harness_blender import fresh, frame_all, export_glb, render, turntable, export_stl, report fresh() # empty scene, millimetres, Workbench matcap bpy.ops.mesh.primitive_cylinder_add(vertices=96, radius=45, depth=100, location=(0, 0, 50)) body = bpy.context.active_object body.name = "Mug" # the name the pane's outliner shows frame_all() # camera + key light framing everything export_glb("out/model.glb") # FIRST: the 3D pane reloads now, in place render("out/preview.png") # a still, seconds (engine="CYCLES", samples=64 for a beauty shot) turntable("out/turntable.mp4", seconds=4) # the pane's Turntable tab; the scene is left as it was report() # what the verdict reads ``` ## What the pane shows, and how to feed it The pane is a 3D viewport of the glTF, not a video player. `export_glb` carries everything it needs: - **Names and hierarchy**: every renderable object under its Blender name, collections as the outliner's tree, parenting kept. Name objects, collections and materials for what they are. - **Facts per object** (as glTF `extras`): dimensions and location in mm, rotation, scale, vertex / face / triangle counts, modifiers, materials, collections. Your own custom properties (`obj["part_no"] = "A-12"`) appear in the properties panel too. - **Materials**: Principled BSDF base colour, metallic, roughness, textures; `diffuse_color` is what Solid shading uses — set it to match. - **The scene camera and lights** (KHR_lights_punctual): the user can look through the camera (numpad 0) and switch the lights on in Material / Rendered shading. - **Animation**: keyframed objects play on the pane's timeline (`obj.keyframe_insert(...)`, `scene.frame_end`, `scene.render.fps`). - **Units**: the scene's unit scale travels with the export, so millimetres read as millimetres. While a script runs, the helper writes `.harness/build.json` (step, turntable progress, failure) and the pane shows "Rebuilding · …" over the last good model. Exports are written to a hidden file and renamed into place, so the pane never reads half a file. Export after every meaningful change. ## Modelling, the parts that matter - **Primitives**: `primitive_cube_add(size)`, `primitive_cylinder_add(vertices, radius, depth)`, `primitive_uv_sphere_add(radius)`, `primitive_torus_add(major_radius, minor_radius)`, `primitive_plane_add`. Each becomes `bpy.context.active_object`; name it. - **Collections**: `c = bpy.data.collections.new("Lamp"); bpy.context.scene.collection.children.link(c)`, then move an object: `for u in list(o.users_collection): u.objects.unlink(o)` and `c.objects.link(o)`. - **Modifiers** (non-destructive, applied on export): `o.modifiers.new("Bevel", "BEVEL")` (width, segments, `limit_method="ANGLE"`), `"SUBSURF"` (levels), `"BOOLEAN"` (operation DIFFERENCE/UNION, object — hide the cutter with `hide_render = True`), `"ARRAY"`, `"MIRROR"`, `"SOLIDIFY"` (thickness — a clean way to give an open shape a wall), `"SCREW"`, `"DISPLACE"`. - **Smooth shading**: `bpy.ops.object.shade_smooth_by_angle(angle=math.radians(35))` on curved parts. - **Edit-mode ops** when a modifier will not do: `bmesh` for exact geometry (`bmesh.ops.extrude_face_region`, `inset`, `bevel`, `delete`), then back to the mesh. - **Curves and text**: `bpy.data.curves.new(type="FONT")` + `body` for lettering, `extrude` for depth. - **Materials**: `bpy.data.materials.new`, `use_nodes = True`, Principled BSDF inputs `Base Color`, `Roughness`, `Metallic`; set `diffuse_color` too so Workbench and the pane's Solid mode show it. - **Units**: `fresh()` puts the scene in millimetres. Model at real size; the report says the size. - **Cameras**: `frame_all(azimuth, elevation)` for the shot; `render(engine="CYCLES")` for light, shadow and glass (CPU: 64 samples at 1280×720 is under a minute for a small scene). - **Animation**: `obj.keyframe_insert("location", frame=n)`; `scene.frame_end`; it exports and plays on the pane's timeline. - **Geometry Nodes** exist (`modifiers.new(type="NODES")`) but hand-built node trees are long; prefer modifiers and bmesh unless the request is procedural by nature. ## Rules - Never write inside the package; `out/` holds everything produced, `scenes/` the scripts. - First a blocky version (primitives, no bevels), **export it**, then render; then refine and export again. The live 3D scene is the proof; the turntable is the deliverable. - Deliver `out/model.glb` (and `.stl` when it is for printing); say the size in mm.