initial migration, not vetted

blender/render_stl_variants.py

@@ -0,0 +1,222 @@
+#!/usr/bin/env python3
+# 20260228 ChatGPT
+# $Header$
+# $Id$
+#
+# Usage:
+#   blender -b -P render_stl_variants.py -- /path/to/part.stl /path/to/out_prefix
+#
+# Output:
+#   <out_prefix>_solid.png
+#   <out_prefix>_solid_edges.png
+#   <out_prefix>_wire.png
+#   <out_prefix>_matcap.png
+#   <out_prefix>_freestyle.png
+#
+# Notes:
+# - Uses orthographic camera + fit-to-bounds framing (consistent prints).
+# - Workbench engine for fast technical-looking renders.
+# - Freestyle enabled only for the freestyle variant.
+
+import bpy
+import sys
+import math
+from mathutils import Vector
+
+def die(msg):
+    print(msg, file=sys.stderr)
+    raise SystemExit(1)
+
+def argv_after_double_dash():
+    if "--" not in sys.argv:
+        return []
+    return sys.argv[sys.argv.index("--") + 1:]
+
+def reset_scene():
+    bpy.ops.wm.read_factory_settings(use_empty=True)
+    scene = bpy.context.scene
+    scene.unit_settings.system = 'NONE'
+    scene.render.resolution_x = 1200
+    scene.render.resolution_y = 1200
+    scene.render.film_transparent = False
+    scene.render.image_settings.file_format = 'PNG'
+    return scene
+
+def import_stl(path):
+    bpy.ops.import_mesh.stl(filepath=path)
+    objs = [o for o in bpy.context.selected_objects if o.type == 'MESH']
+    if not objs:
+        die(f"Failed to import STL: {path}")
+    # join into one object for consistent bounds
+    bpy.context.view_layer.objects.active = objs[0]
+    for o in objs:
+        o.select_set(True)
+    bpy.ops.object.join()
+    obj = bpy.context.view_layer.objects.active
+    obj.name = "PART"
+    return obj
+
+def center_origin_and_location(obj):
+    bpy.context.view_layer.objects.active = obj
+    obj.select_set(True)
+    bpy.ops.object.origin_set(type='ORIGIN_GEOMETRY', center='BOUNDS')
+    obj.location = (0, 0, 0)
+
+def bounds_world(obj):
+    # bounding box corners in world coordinates
+    mw = obj.matrix_world
+    corners = [mw @ Vector(c) for c in obj.bound_box]
+    xs = [c.x for c in corners]; ys = [c.y for c in corners]; zs = [c.z for c in corners]
+    min_v = Vector((min(xs), min(ys), min(zs)))
+    max_v = Vector((max(xs), max(ys), max(zs)))
+    size = max_v - min_v
+    center = (min_v + max_v) / 2.0
+    return center, size
+
+def ensure_camera(scene):
+    cam_data = bpy.data.cameras.new("OrthoCam")
+    cam_data.type = 'ORTHO'
+    cam = bpy.data.objects.new("OrthoCam", cam_data)
+    scene.collection.objects.link(cam)
+    scene.camera = cam
+    return cam
+
+def ensure_light_rig(scene):
+    # For workbench it barely matters, but keep a light for non-workbench fallback
+    ld = bpy.data.lights.new("Key", type='AREA')
+    lo = bpy.data.objects.new("Key", ld)
+    lo.location = (3, -3, 3)
+    scene.collection.objects.link(lo)
+
+def set_isometric_camera(cam, target=(0,0,0), ortho_scale=2.0):
+    cam.data.ortho_scale = ortho_scale
+    cam.location = (3.0, -3.0, 3.0)
+    cam.rotation_euler = (math.radians(55), 0, math.radians(45))
+
+def fit_camera_to_object(cam, obj, margin=1.15):
+    center, size = bounds_world(obj)
+    max_dim = max(size.x, size.y, size.z)
+    # ortho_scale roughly maps to view width; margin gives padding
+    cam.data.ortho_scale = max_dim * margin
+
+def set_world_background(scene, gray=1.0):
+    # Simple white/gray background via World color
+    if scene.world is None:
+        scene.world = bpy.data.worlds.new("World")
+    scene.world.use_nodes = False
+    scene.world.color = (gray, gray, gray)
+
+def workbench_common(scene):
+    scene.render.engine = 'BLENDER_WORKBENCH'
+    scene.display.shading.light = 'STUDIO'
+    scene.display.shading.color_type = 'SINGLE'
+    scene.display.shading.single_color = (0.82, 0.82, 0.82)  # light gray “clay”
+    scene.display.shading.show_backface_culling = False
+    scene.display.shading.show_xray = False
+
+def variant_solid(scene):
+    workbench_common(scene)
+    scene.display.shading.show_wireframes = False
+
+def variant_wire(scene):
+    workbench_common(scene)
+    scene.display.shading.show_wireframes = True
+    scene.display.shading.wireframe_color_type = 'SINGLE'
+    scene.display.shading.wireframe_color = (0.0, 0.0, 0.0)
+    scene.display.shading.wireframe_opacity = 1.0
+    scene.display.shading.wireframe_thickness = 1
+
+def variant_solid_edges(scene):
+    # Workbench wire overlay on top of solid
+    workbench_common(scene)
+    scene.display.shading.show_wireframes = True
+    scene.display.shading.wireframe_color_type = 'SINGLE'
+    scene.display.shading.wireframe_color = (0.0, 0.0, 0.0)
+    scene.display.shading.wireframe_opacity = 1.0
+    scene.display.shading.wireframe_thickness = 1
+
+def variant_matcap(scene):
+    # Workbench “Matcap-like” studio + cavity (helps valleys/holes read on paper)
+    workbench_common(scene)
+    scene.display.shading.show_wireframes = False
+    scene.display.shading.show_cavity = True
+    scene.display.shading.cavity_type = 'WORLD'
+    scene.display.shading.cavity_ridge_factor = 1.0
+    scene.display.shading.cavity_valley_factor = 1.0
+
+def variant_freestyle(scene):
+    # Freestyle line drawing + light solid base
+    # Works with Workbench in many cases, but Freestyle is historically tied to Eevee/Cycles.
+    # Here we switch to Eevee for reliability.
+    scene.render.engine = 'BLENDER_EEVEE'
+    scene.eevee.use_gtao = True
+    scene.render.film_transparent = False
+
+    # Setup simple material
+    mat = bpy.data.materials.new("Clay")
+    mat.use_nodes = True
+    bsdf = mat.node_tree.nodes.get("Principled BSDF")
+    bsdf.inputs["Base Color"].default_value = (0.85, 0.85, 0.85, 1.0)
+    bsdf.inputs["Roughness"].default_value = 1.0
+
+    obj = bpy.data.objects.get("PART")
+    if obj and obj.data.materials:
+        obj.data.materials[0] = mat
+    elif obj:
+        obj.data.materials.append(mat)
+
+    # Enable Freestyle
+    scene.render.use_freestyle = True
+    # Default freestyle line set is OK; keep lines black and modest thickness
+    if scene.view_layers:
+        vl = scene.view_layers[0]
+        vl.freestyle_settings.linesets.new("LineSet") if not vl.freestyle_settings.linesets else None
+    # Render Properties -> Freestyle settings are somewhat verbose to tune; default is acceptable for v1.
+
+def render(scene, outpath):
+    scene.render.filepath = outpath
+    bpy.ops.render.render(write_still=True)
+
+def main():
+    args = argv_after_double_dash()
+    if len(args) != 2:
+        die("Expected: <input.stl> <out_prefix>")
+
+    in_stl, out_prefix = args
+    scene = reset_scene()
+    obj = import_stl(in_stl)
+    center_origin_and_location(obj)
+    ensure_light_rig(scene)
+    cam = ensure_camera(scene)
+    set_isometric_camera(cam)
+    fit_camera_to_object(cam, obj, margin=1.20)
+    set_world_background(scene, gray=1.0)
+
+    # SOLID
+    variant_solid(scene)
+    scene.render.use_freestyle = False
+    render(scene, f"{out_prefix}_solid.png")
+
+    # SOLID + EDGES
+    variant_solid_edges(scene)
+    scene.render.use_freestyle = False
+    render(scene, f"{out_prefix}_solid_edges.png")
+
+    # WIRE
+    variant_wire(scene)
+    scene.render.use_freestyle = False
+    render(scene, f"{out_prefix}_wire.png")
+
+    # MATCAP-ish (cavity)
+    variant_matcap(scene)
+    scene.render.use_freestyle = False
+    render(scene, f"{out_prefix}_matcap.png")
+
+    # FREESTYLE
+    variant_freestyle(scene)
+    render(scene, f"{out_prefix}_freestyle.png")
+
+    print("Done.")
+
+if __name__ == "__main__":
+    main()