feat: initial commit

2026-03-05 22:12:38 +01:00
commit bce762a783
380 changed files with 51955 additions and 0 deletions
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+"""Blender Python script: turntable animation render for Flamenco.
+
+Usage (from Blender):
+  blender --background --python turntable_render.py -- \
+    <stl_path> <frames_dir> <frame_count> <degrees> <width> <height> \
+    <engine> <samples> <part_colors_json> \
+    [template_path] [target_collection] [material_library_path] [material_map_json]
+"""
+import bpy
+import sys
+import os
+import json
+import math
+from mathutils import Vector, Matrix
+
+# ── Colour palette (matches blender_render.py / Three.js renderer) ───────────
+PALETTE_HEX = [
+    "#4C9BE8", "#E85B4C", "#4CBE72", "#E8A84C", "#A04CE8",
+    "#4CD4E8", "#E84CA8", "#7EC850", "#E86B30", "#5088C8",
+]
+
+def _srgb_to_linear(c: int) -> float:
+    v = c / 255.0
+    return v / 12.92 if v <= 0.04045 else ((v + 0.055) / 1.055) ** 2.4
+
+def _hex_to_linear(hex_color: str) -> tuple:
+    h = hex_color.lstrip('#')
+    return (
+        _srgb_to_linear(int(h[0:2], 16)),
+        _srgb_to_linear(int(h[2:4], 16)),
+        _srgb_to_linear(int(h[4:6], 16)),
+        1.0,
+    )
+
+PALETTE_LINEAR = [_hex_to_linear(h) for h in PALETTE_HEX]
+
+SMOOTH_ANGLE = 30  # degrees
+
+
+# ── Helper functions ─────────────────────────────────────────────────────────
+
+def _ensure_collection(name: str):
+    """Return a collection by name, creating it if needed."""
+    if name in bpy.data.collections:
+        return bpy.data.collections[name]
+    col = bpy.data.collections.new(name)
+    bpy.context.scene.collection.children.link(col)
+    return col
+
+
+def _assign_palette_material(part_obj, index):
+    """Assign a palette colour material to a mesh part."""
+    color = PALETTE_LINEAR[index % len(PALETTE_LINEAR)]
+    mat = bpy.data.materials.new(name=f"Part_{index}")
+    mat.use_nodes = True
+    bsdf = mat.node_tree.nodes.get("Principled BSDF")
+    if bsdf:
+        bsdf.inputs["Base Color"].default_value = color
+        bsdf.inputs["Metallic"].default_value = 0.35
+        bsdf.inputs["Roughness"].default_value = 0.40
+        try:
+            bsdf.inputs["Specular IOR Level"].default_value = 0.5
+        except KeyError:
+            pass
+    part_obj.data.materials.clear()
+    part_obj.data.materials.append(mat)
+
+
+def _apply_smooth(part_obj, angle_deg):
+    """Apply smooth or flat shading to a mesh object."""
+    bpy.context.view_layer.objects.active = part_obj
+    part_obj.select_set(True)
+    if angle_deg > 0:
+        try:
+            bpy.ops.object.shade_smooth_by_angle(angle=math.radians(angle_deg))
+        except AttributeError:
+            bpy.ops.object.shade_smooth()
+            part_obj.data.use_auto_smooth = True
+            part_obj.data.auto_smooth_angle = math.radians(angle_deg)
+    else:
+        bpy.ops.object.shade_flat()
+
+
+import re as _re
+
+
+def _apply_rotation(parts, rx, ry, rz):
+    """Apply Euler XYZ rotation (degrees) to all parts by modifying matrix_world.
+
+    Rotates around world origin, which equals the assembly centre because
+    _import_stl already centres parts there.  Applied before material assignment
+    and camera/bbox calculations so everything downstream sees the final pose.
+    """
+    if not parts or (rx == 0.0 and ry == 0.0 and rz == 0.0):
+        return
+    from mathutils import Euler
+    rot_mat = Euler((math.radians(rx), math.radians(ry), math.radians(rz)), 'XYZ').to_matrix().to_4x4()
+    for p in parts:
+        p.matrix_world = rot_mat @ p.matrix_world
+    bpy.ops.object.select_all(action='DESELECT')
+    for p in parts:
+        p.select_set(True)
+    bpy.context.view_layer.objects.active = parts[0]
+    bpy.ops.object.transform_apply(location=False, rotation=True, scale=False)
+    print(f"[turntable_render] applied rotation ({rx}°, {ry}°, {rz}°) to {len(parts)} parts")
+
+
+def _axis_rotation(axis: str, degrees: float) -> tuple:
+    """Map turntable axis name to Euler (x, y, z) rotation in radians."""
+    rad = math.radians(degrees)
+    if axis == "world_x":
+        return (rad, 0.0, 0.0)
+    elif axis == "world_y":
+        return (0.0, rad, 0.0)
+    else:  # "world_z" default
+        return (0.0, 0.0, rad)
+
+
+def _set_fcurves_linear(action):
+    """Set LINEAR interpolation on all fcurves.
+
+    Handles both the legacy Blender < 4.4 API (action.fcurves) and the new
+    Baklava layered-action API introduced in Blender 4.4 / 5.x
+    (action.layers[*].strips[*].channelbags[*].fcurves).
+    """
+    try:
+        # New layered-action API (Blender 4.4+ / 5.x)
+        for layer in action.layers:
+            for strip in layer.strips:
+                for channelbag in strip.channelbags:
+                    for fc in channelbag.fcurves:
+                        for kp in fc.keyframe_points:
+                            kp.interpolation = 'LINEAR'
+    except AttributeError:
+        # Legacy API (Blender < 4.4)
+        for fc in action.fcurves:
+            for kp in fc.keyframe_points:
+                kp.interpolation = 'LINEAR'
+
+
+def _scale_mm_to_m(parts):
+    """Scale imported STL objects from mm to Blender metres (×0.001).
+
+    STEP/STL coordinates are in mm; Blender's default unit is metres.
+    Without scaling a 50 mm part appears as 50 m inside Blender — way too large
+    relative to any template environment designed in metric units.
+    """
+    if not parts:
+        return
+    bpy.ops.object.select_all(action='DESELECT')
+    for p in parts:
+        p.scale = (0.001, 0.001, 0.001)
+        p.location *= 0.001
+        p.select_set(True)
+    bpy.context.view_layer.objects.active = parts[0]
+    bpy.ops.object.transform_apply(scale=True, location=False, rotation=False)
+    print(f"[turntable_render] scaled {len(parts)} parts mm→m (×0.001)")
+
+
+def _import_stl(stl_file):
+    """Import STL into Blender, using per-part STLs if available.
+
+    Checks for {stl_stem}_parts/manifest.json next to the STL file.
+    - Per-part mode: imports each part STL, names Blender object after STEP part name.
+    - Fallback: imports combined STL and splits by loose geometry.
+
+    Returns list of Blender mesh objects, centred at origin.
+    """
+    stl_dir = os.path.dirname(stl_file)
+    stl_stem = os.path.splitext(os.path.basename(stl_file))[0]
+    parts_dir = os.path.join(stl_dir, stl_stem + "_parts")
+    manifest_path = os.path.join(parts_dir, "manifest.json")
+
+    parts = []
+
+    if os.path.isfile(manifest_path):
+        # ── Per-part mode ────────────────────────────────────────────────
+        try:
+            with open(manifest_path, "r") as f:
+                manifest = json.loads(f.read())
+            part_entries = manifest.get("parts", [])
+        except Exception as e:
+            print(f"[turntable_render] WARNING: failed to read manifest: {e}")
+            part_entries = []
+
+        if part_entries:
+            for entry in part_entries:
+                part_file = os.path.join(parts_dir, entry["file"])
+                part_name = entry["name"]
+                if not os.path.isfile(part_file):
+                    print(f"[turntable_render] WARNING: part STL missing: {part_file}")
+                    continue
+
+                bpy.ops.object.select_all(action='DESELECT')
+                bpy.ops.wm.stl_import(filepath=part_file)
+                imported = bpy.context.selected_objects
+                if imported:
+                    obj = imported[0]
+                    obj.name = part_name
+                    if obj.data:
+                        obj.data.name = part_name
+                    parts.append(obj)
+
+            if parts:
+                print(f"[turntable_render] imported {len(parts)} named parts from per-part STLs")
+
+    # ── Fallback: combined STL + separate by loose ───────────────────────
+    if not parts:
+        bpy.ops.wm.stl_import(filepath=stl_file)
+        obj = bpy.context.selected_objects[0] if bpy.context.selected_objects else None
+        if obj is None:
+            print(f"ERROR: No objects imported from {stl_file}")
+            sys.exit(1)
+
+        bpy.context.view_layer.objects.active = obj
+        bpy.ops.object.origin_set(type='ORIGIN_GEOMETRY', center='BOUNDS')
+        obj.location = (0.0, 0.0, 0.0)
+
+        bpy.ops.object.mode_set(mode='EDIT')
+        bpy.ops.mesh.separate(type='LOOSE')
+        bpy.ops.object.mode_set(mode='OBJECT')
+
+        parts = list(bpy.context.selected_objects)
+        print(f"[turntable_render] fallback: separated into {len(parts)} part(s)")
+        return parts
+
+    # ── Centre per-part imports at origin (combined bbox) ────────────────
+    all_corners = []
+    for p in parts:
+        all_corners.extend(p.matrix_world @ Vector(c) for c in p.bound_box)
+
+    if all_corners:
+        mins = Vector((min(v.x for v in all_corners),
+                        min(v.y for v in all_corners),
+                        min(v.z for v in all_corners)))
+        maxs = Vector((max(v.x for v in all_corners),
+                        max(v.y for v in all_corners),
+                        max(v.z for v in all_corners)))
+        center = (mins + maxs) * 0.5
+        for p in parts:
+            p.location -= center
+
+    return parts
+
+
+def _resolve_part_name(index, part_obj, part_names_ordered):
+    """Get the STEP part name for a Blender part by index.
+
+    With per-part import, part_obj.name IS the STEP name (possibly with
+    Blender .NNN suffix). Falls back to part_names_ordered for combined-STL mode.
+    """
+    base_name = _re.sub(r'\.\d{3}$', '', part_obj.name)
+    if part_names_ordered and index < len(part_names_ordered):
+        return part_names_ordered[index]
+    return base_name
+
+
+def _apply_material_library(parts, mat_lib_path, mat_map, part_names_ordered=None):
+    """Append materials from library .blend and assign to parts via material_map.
+
+    With per-part STL import, Blender objects are named after STEP parts,
+    so matching is by name (stripping Blender .NNN suffix for duplicates).
+    Falls back to part_names_ordered index-based matching for combined-STL mode.
+
+    mat_map: {part_name_lower: material_name}
+    Parts without a match keep their current material.
+    """
+    if not mat_lib_path or not os.path.isfile(mat_lib_path):
+        print(f"[turntable_render] material library not found: {mat_lib_path}")
+        return
+
+    # Collect unique material names needed
+    needed = set(mat_map.values())
+    if not needed:
+        return
+
+    # Append materials from library
+    appended = {}
+    for mat_name in needed:
+        inner_path = f"{mat_lib_path}/Material/{mat_name}"
+        try:
+            bpy.ops.wm.append(
+                filepath=inner_path,
+                directory=f"{mat_lib_path}/Material/",
+                filename=mat_name,
+                link=False,
+            )
+            if mat_name in bpy.data.materials:
+                appended[mat_name] = bpy.data.materials[mat_name]
+                print(f"[turntable_render] appended material: {mat_name}")
+            else:
+                print(f"[turntable_render] WARNING: material '{mat_name}' not found after append")
+        except Exception as exc:
+            print(f"[turntable_render] WARNING: failed to append material '{mat_name}': {exc}")
+
+    if not appended:
+        return
+
+    # Assign materials to parts — primary: name-based (per-part STL mode),
+    # secondary: index-based via part_names_ordered (combined STL fallback)
+    assigned_count = 0
+    for i, part in enumerate(parts):
+        # Try name-based matching first (strip Blender .NNN suffix)
+        base_name = _re.sub(r'\.\d{3}$', '', part.name)
+        part_key = base_name.lower().strip()
+        mat_name = mat_map.get(part_key)
+
+        # Fall back to index-based matching via part_names_ordered
+        if not mat_name and part_names_ordered and i < len(part_names_ordered):
+            step_name = part_names_ordered[i]
+            part_key = step_name.lower().strip()
+            mat_name = mat_map.get(part_key)
+
+        if mat_name and mat_name in appended:
+            part.data.materials.clear()
+            part.data.materials.append(appended[mat_name])
+            assigned_count += 1
+            print(f"[turntable_render] assigned '{mat_name}' to part '{part.name}'")
+
+    print(f"[turntable_render] material assignment: {assigned_count}/{len(parts)} parts matched")
+
+
+def main():
+    argv = sys.argv
+    # Everything after "--" is our args
+    args = argv[argv.index("--") + 1:]
+
+    stl_path = args[0]
+    frames_dir = args[1]
+    frame_count = int(args[2])
+    degrees = int(args[3])
+    width = int(args[4])
+    height = int(args[5])
+    engine = args[6]
+    samples = int(args[7])
+    part_colors_json = args[8] if len(args) > 8 else "{}"
+
+    # Template + material library args (passed by schaeffler-turntable.js)
+    template_path = args[9] if len(args) > 9 and args[9] else ""
+    target_collection = args[10] if len(args) > 10 else "Product"
+    material_library_path = args[11] if len(args) > 11 and args[11] else ""
+    material_map_raw = args[12] if len(args) > 12 else "{}"
+    part_names_ordered_raw = args[13] if len(args) > 13 else "[]"
+    lighting_only = args[14] == "1" if len(args) > 14 else False
+    cycles_device = args[15].lower() if len(args) > 15 else "auto"  # "auto", "gpu", "cpu"
+    shadow_catcher = args[16] == "1" if len(args) > 16 else False
+    rotation_x = float(args[17]) if len(args) > 17 else 0.0
+    rotation_y = float(args[18]) if len(args) > 18 else 0.0
+    rotation_z = float(args[19]) if len(args) > 19 else 0.0
+    turntable_axis = args[20] if len(args) > 20 else "world_z"
+    bg_color = args[21] if len(args) > 21 else ""
+    transparent_bg = args[22] == "1" if len(args) > 22 else False
+
+    os.makedirs(frames_dir, exist_ok=True)
+
+    try:
+        part_colors = json.loads(part_colors_json)
+    except json.JSONDecodeError:
+        part_colors = {}
+
+    try:
+        material_map = json.loads(material_map_raw) if material_map_raw else {}
+    except json.JSONDecodeError:
+        material_map = {}
+
+    try:
+        part_names_ordered = json.loads(part_names_ordered_raw) if part_names_ordered_raw else []
+    except json.JSONDecodeError:
+        part_names_ordered = []
+
+    # Validate template path: if provided it MUST exist on disk.
+    if template_path and not os.path.isfile(template_path):
+        print(f"[turntable_render] ERROR: template_path was provided but file not found: {template_path}")
+        print("[turntable_render] Ensure the blend-templates directory is accessible on this worker.")
+        sys.exit(1)
+
+    use_template = bool(template_path)
+
+    print(f"[turntable_render] engine={engine}, samples={samples}, size={width}x{height}, "
+          f"frames={frame_count}, degrees={degrees}")
+    print(f"[turntable_render] part_names_ordered: {len(part_names_ordered)} entries")
+    if use_template:
+        print(f"[turntable_render] template={template_path}, collection={target_collection}, lighting_only={lighting_only}")
+    else:
+        print("[turntable_render] no template — using factory settings (Mode A)")
+    if material_library_path:
+        print(f"[turntable_render] material_library={material_library_path}, material_map keys={list(material_map.keys())}")
+
+    # ── SCENE SETUP ──────────────────────────────────────────────────────────
+
+    if use_template:
+        # ── MODE B: Template-based render ────────────────────────────────────
+        print(f"[turntable_render] Opening template: {template_path}")
+        bpy.ops.wm.open_mainfile(filepath=template_path)
+
+        # Find or create target collection
+        target_col = _ensure_collection(target_collection)
+
+        # Import and split STL
+        parts = _import_stl(stl_path)
+        # Scale mm→m: STEP coords are mm, Blender default unit is metres
+        _scale_mm_to_m(parts)
+        # Apply render position rotation before material/camera setup
+        _apply_rotation(parts, rotation_x, rotation_y, rotation_z)
+
+        # Move imported parts into target collection
+        for part in parts:
+            for col in list(part.users_collection):
+                col.objects.unlink(part)
+            target_col.objects.link(part)
+
+        # Apply smooth shading
+        for part in parts:
+            _apply_smooth(part, SMOOTH_ANGLE)
+
+        # Material assignment: library materials if available, otherwise palette
+        if material_library_path and material_map:
+            mat_map_lower = {k.lower(): v for k, v in material_map.items()}
+            _apply_material_library(parts, material_library_path, mat_map_lower, part_names_ordered)
+            # Parts not matched by library get palette fallback
+            for i, part in enumerate(parts):
+                if not part.data.materials or len(part.data.materials) == 0:
+                    _assign_palette_material(part, i)
+        else:
+            for i, part in enumerate(parts):
+                step_name = _resolve_part_name(i, part, part_names_ordered)
+                color_hex = part_colors.get(step_name)
+                if not color_hex:
+                    _assign_palette_material(part, i)
+
+        # ── Shadow catcher (Cycles only, template mode only) ─────────────────
+        if shadow_catcher:
+            sc_col_name = "Shadowcatcher"
+            sc_obj_name = "Shadowcatcher"
+            for vl in bpy.context.scene.view_layers:
+                def _enable_col_recursive(layer_col):
+                    if layer_col.collection.name == sc_col_name:
+                        layer_col.exclude = False
+                        layer_col.collection.hide_render = False
+                        layer_col.collection.hide_viewport = False
+                        return True
+                    for child in layer_col.children:
+                        if _enable_col_recursive(child):
+                            return True
+                    return False
+                _enable_col_recursive(vl.layer_collection)
+
+            sc_obj = bpy.data.objects.get(sc_obj_name)
+            if sc_obj:
+                all_world_z = []
+                for part in parts:
+                    for corner in part.bound_box:
+                        all_world_z.append((part.matrix_world @ Vector(corner)).z)
+                if all_world_z:
+                    sc_obj.location.z = min(all_world_z)
+                print(f"[turntable_render] shadow catcher enabled, plane Z={sc_obj.location.z:.4f}")
+            else:
+                print(f"[turntable_render] WARNING: shadow catcher object '{sc_obj_name}' not found in template")
+
+        # lighting_only: always use auto-framing; normal template: use camera if present
+        needs_auto_camera = (lighting_only and not shadow_catcher) or not bpy.context.scene.camera
+        if lighting_only and not shadow_catcher:
+            print("[turntable_render] lighting_only mode: using template World/HDRI, forcing auto-camera")
+        elif needs_auto_camera:
+            print("[turntable_render] WARNING: template has no camera — will create auto-camera")
+
+        # Set very close near clip on template camera for mm-scale parts (now in metres)
+        if not needs_auto_camera and bpy.context.scene.camera:
+            bpy.context.scene.camera.data.clip_start = 0.001
+
+        print(f"[turntable_render] template mode: {len(parts)} parts imported into collection '{target_collection}'")
+
+    else:
+        # ── MODE A: Factory settings ─────────────────────────────────────────
+        needs_auto_camera = True
+        bpy.ops.wm.read_factory_settings(use_empty=True)
+
+        parts = _import_stl(stl_path)
+        # Scale mm→m: STEP coords are mm, Blender default unit is metres
+        _scale_mm_to_m(parts)
+        # Apply render position rotation before material/camera setup
+        _apply_rotation(parts, rotation_x, rotation_y, rotation_z)
+
+        for i, part in enumerate(parts):
+            _apply_smooth(part, SMOOTH_ANGLE)
+
+        # Material assignment: library materials if available, else part_colors/palette
+        if material_library_path and material_map:
+            mat_map_lower = {k.lower(): v for k, v in material_map.items()}
+            _apply_material_library(parts, material_library_path, mat_map_lower, part_names_ordered)
+            # Palette fallback for unmatched parts
+            for i, part in enumerate(parts):
+                if not part.data.materials or len(part.data.materials) == 0:
+                    _assign_palette_material(part, i)
+        else:
+            # part_colors or palette — use index-based lookup via part_names_ordered
+            for i, part in enumerate(parts):
+                step_name = _resolve_part_name(i, part, part_names_ordered)
+                color_hex = part_colors.get(step_name)
+                if color_hex:
+                    mat = bpy.data.materials.new(name=f"mat_{part.name}")
+                    mat.use_nodes = True
+                    bsdf = mat.node_tree.nodes.get("Principled BSDF")
+                    if bsdf:
+                        color = _hex_to_linear(color_hex)
+                        bsdf.inputs["Base Color"].default_value = color
+                        bsdf.inputs["Metallic"].default_value = 0.35
+                        bsdf.inputs["Roughness"].default_value = 0.40
+                        try:
+                            bsdf.inputs["Specular IOR Level"].default_value = 0.5
+                        except KeyError:
+                            pass
+                    part.data.materials.clear()
+                    part.data.materials.append(mat)
+                else:
+                    _assign_palette_material(part, i)
+
+    if needs_auto_camera:
+        # ── Combined bounding box / bounding sphere ──────────────────────────
+        all_corners = []
+        for part in parts:
+            all_corners.extend(part.matrix_world @ Vector(c) for c in part.bound_box)
+
+        bbox_min = Vector((
+            min(v.x for v in all_corners),
+            min(v.y for v in all_corners),
+            min(v.z for v in all_corners),
+        ))
+        bbox_max = Vector((
+            max(v.x for v in all_corners),
+            max(v.y for v in all_corners),
+            max(v.z for v in all_corners),
+        ))
+
+        bbox_center = (bbox_min + bbox_max) * 0.5
+        bbox_dims = bbox_max - bbox_min
+        bsphere_radius = max(bbox_dims.length * 0.5, 0.001)
+
+        print(f"[turntable_render] bbox_dims={tuple(round(d, 4) for d in bbox_dims)}, "
+              f"bsphere_radius={bsphere_radius:.4f}")
+
+        # ── Lighting — only in Mode A (factory settings) ─────────────────────
+        # In template mode the .blend file provides its own World/HDRI lighting.
+        # Adding auto-lights would overpower the template's intended look.
+        if not use_template:
+            light_dist = bsphere_radius * 6.0
+
+            bpy.ops.object.light_add(type='SUN', location=(
+                bbox_center.x + light_dist * 0.5,
+                bbox_center.y - light_dist * 0.35,
+                bbox_center.z + light_dist,
+            ))
+            sun = bpy.context.active_object
+            sun.data.energy = 4.0
+            sun.rotation_euler = (math.radians(45), 0, math.radians(30))
+
+            bpy.ops.object.light_add(type='AREA', location=(
+                bbox_center.x - light_dist * 0.4,
+                bbox_center.y + light_dist * 0.4,
+                bbox_center.z + light_dist * 0.7,
+            ))
+            fill = bpy.context.active_object
+            fill.data.energy = max(800.0, bsphere_radius ** 2 * 2000.0)
+            fill.data.size = max(4.0, bsphere_radius * 4.0)
+
+        # ── Camera ───────────────────────────────────────────────────────────
+        cam_dist = bsphere_radius * 2.5
+        cam_location = Vector((
+            bbox_center.x + cam_dist,
+            bbox_center.y,
+            bbox_center.z + bsphere_radius * 0.5,
+        ))
+        bpy.ops.object.camera_add(location=cam_location)
+        camera = bpy.context.active_object
+        bpy.context.scene.camera = camera
+        camera.data.clip_start = max(cam_dist * 0.001, 0.0001)
+        camera.data.clip_end = cam_dist * 10.0
+
+        # Track-to constraint for look-at
+        empty = bpy.data.objects.new("target", None)
+        bpy.context.collection.objects.link(empty)
+        empty.location = bbox_center
+
+        track = camera.constraints.new(type='TRACK_TO')
+        track.target = empty
+        track.track_axis = 'TRACK_NEGATIVE_Z'
+        track.up_axis = 'UP_Y'
+
+        # ── World background — only in Mode A ───────────────────────────────
+        # In template mode the .blend file owns its World (HDRI, sky texture,
+        # studio lighting).  Overwriting it would destroy the HDR look.
+        if not use_template:
+            world = bpy.data.worlds.new("World")
+            bpy.context.scene.world = world
+            world.use_nodes = True
+            bg = world.node_tree.nodes["Background"]
+            bg.inputs["Color"].default_value = (0.96, 0.96, 0.97, 1.0)
+            bg.inputs["Strength"].default_value = 0.15
+
+        # ── Turntable pivot ──────────────────────────────────────────────────
+        pivot = bpy.data.objects.new("pivot", None)
+        bpy.context.collection.objects.link(pivot)
+        pivot.location = bbox_center
+
+        # Parent camera to pivot
+        camera.parent = pivot
+        camera.location = (cam_dist, 0, bsphere_radius * 0.5)
+
+        # Keyframe pivot rotation
+        scene = bpy.context.scene
+        scene.frame_start = 1
+        scene.frame_end = frame_count
+
+        pivot.rotation_euler = (0, 0, 0)
+        pivot.keyframe_insert(data_path="rotation_euler", frame=1)
+        pivot.rotation_euler = _axis_rotation(turntable_axis, degrees)
+        pivot.keyframe_insert(data_path="rotation_euler", frame=frame_count + 1)
+
+        # Linear interpolation — frame N+1 is never rendered, giving N uniform steps
+        _set_fcurves_linear(pivot.animation_data.action)
+
+    else:
+        # Template has camera — set up turntable on the model parts instead
+        scene = bpy.context.scene
+        scene.frame_start = 1
+        scene.frame_end = frame_count
+
+        # Calculate model center for pivot
+        all_corners = []
+        for part in parts:
+            all_corners.extend(part.matrix_world @ Vector(c) for c in part.bound_box)
+
+        bbox_center = Vector((
+            (min(v.x for v in all_corners) + max(v.x for v in all_corners)) * 0.5,
+            (min(v.y for v in all_corners) + max(v.y for v in all_corners)) * 0.5,
+            (min(v.z for v in all_corners) + max(v.z for v in all_corners)) * 0.5,
+        ))
+
+        # Create a pivot empty and parent all parts to it
+        pivot = bpy.data.objects.new("turntable_pivot", None)
+        bpy.context.collection.objects.link(pivot)
+        pivot.location = bbox_center
+
+        for part in parts:
+            part.parent = pivot
+
+        # Keyframe pivot rotation
+        pivot.rotation_euler = (0, 0, 0)
+        pivot.keyframe_insert(data_path="rotation_euler", frame=1)
+        pivot.rotation_euler = _axis_rotation(turntable_axis, degrees)
+        pivot.keyframe_insert(data_path="rotation_euler", frame=frame_count + 1)
+
+        # Linear interpolation — frame N+1 is never rendered, giving N uniform steps
+        _set_fcurves_linear(pivot.animation_data.action)
+
+    # ── Colour management ────────────────────────────────────────────────────
+    # In template mode the .blend file owns its colour management settings.
+    # Overwriting them would destroy the intended HDR/tonemapping look.
+    # In factory-settings mode force Standard to avoid the grey Filmic tint.
+    scene = bpy.context.scene
+    if not use_template:
+        scene.view_settings.view_transform = 'Standard'
+        scene.view_settings.exposure = 0.0
+        scene.view_settings.gamma = 1.0
+        try:
+            scene.view_settings.look = 'None'
+        except Exception:
+            pass
+
+    # ── Render engine ────────────────────────────────────────────────────────
+    if engine == "eevee":
+        eevee_ok = False
+        for eevee_id in ('BLENDER_EEVEE', 'BLENDER_EEVEE_NEXT'):
+            try:
+                scene.render.engine = eevee_id
+                eevee_ok = True
+                print(f"[turntable_render] EEVEE engine id: {eevee_id}")
+                break
+            except TypeError:
+                continue
+        if eevee_ok:
+            for attr in ('taa_render_samples', 'samples'):
+                try:
+                    setattr(scene.eevee, attr, samples)
+                    break
+                except AttributeError:
+                    continue
+        else:
+            print("[turntable_render] WARNING: EEVEE not available, falling back to Cycles")
+            engine = "cycles"
+
+    if engine != "eevee":
+        scene.render.engine = 'CYCLES'
+        scene.cycles.samples = samples
+        scene.cycles.use_denoising = True
+        scene.cycles.denoiser = 'OPENIMAGEDENOISE'  # GPU-accelerated when CUDA/OptiX active
+        # Device selection: "cpu" forces CPU, "gpu" forces GPU (warns if unavailable),
+        # "auto" (default) tries GPU first and falls back to CPU.
+        print(f"[turntable_render] cycles_device={cycles_device}")
+        gpu_found = False
+        if cycles_device != "cpu":
+            try:
+                cycles_prefs = bpy.context.preferences.addons['cycles'].preferences
+                for device_type in ('OPTIX', 'CUDA', 'HIP', 'ONEAPI'):
+                    try:
+                        cycles_prefs.compute_device_type = device_type
+                        cycles_prefs.get_devices()
+                        gpu_devs = [d for d in cycles_prefs.devices if d.type != 'CPU']
+                        if gpu_devs:
+                            for d in gpu_devs:
+                                d.use = True
+                            scene.cycles.device = 'GPU'
+                            gpu_found = True
+                            print(f"[turntable_render] Cycles GPU ({device_type})")
+                            break
+                    except Exception:
+                        continue
+            except Exception:
+                pass
+        if not gpu_found:
+            scene.cycles.device = 'CPU'
+            print("[turntable_render] WARNING: GPU not found — falling back to CPU")
+
+    # ── Render settings ──────────────────────────────────────────────────────
+    scene.render.resolution_x = width
+    scene.render.resolution_y = height
+    scene.render.resolution_percentage = 100
+    scene.render.image_settings.file_format = 'PNG'
+
+    # ── Transparent background ────────────────────────────────────────────────
+    # bg_color compositing is handled by FFmpeg in the compose-video task.
+    # Blender renders transparent PNG frames when bg_color is set.
+    if bg_color or transparent_bg:
+        scene.render.film_transparent = True
+        if bg_color:
+            print(f"[turntable_render] film_transparent=True for FFmpeg bg_color compositing ({bg_color})")
+        else:
+            print("[turntable_render] transparent_bg enabled (alpha PNG frames)")
+
+    # ── Render all frames ────────────────────────────────────────────────────
+    # Per-frame loop with write_still=True.  In a single Blender session,
+    # Cycles keeps the GPU scene (BVH, textures, material graph) loaded
+    # between frames — only the animated pivot transform is updated each step.
+    # bpy.ops.render.render(animation=True) does NOT work reliably in
+    # background mode after wm.open_mainfile() in Blender 5.x (silently
+    # writes no files), so we use the explicit per-frame approach.
+    import time as _time
+    _render_start = _time.time()
+    for frame in range(1, frame_count + 1):
+        scene.frame_set(frame)
+        scene.render.filepath = os.path.join(frames_dir, f"frame_{frame:04d}")
+        bpy.ops.render.render(write_still=True)
+        elapsed = _time.time() - _render_start
+        fps_so_far = frame / elapsed
+        print(f"[turntable_render] Frame {frame}/{frame_count} — {elapsed:.1f}s elapsed ({fps_so_far:.2f} fps)")
+
+    total = _time.time() - _render_start
+    print(f"[turntable_render] Turntable render complete: {frame_count} frames in {total:.1f}s ({frame_count/total:.2f} fps avg)")
+
+
+if __name__ == "__main__":
+    main()