feat(渲染): 新增线稿渲染功能

添加线稿渲染功能，用于生成 ControlNet Canny 所需的黑白线稿图。实现通过 Freestyle 渲染引擎，在白色背景上生成黑色线条，并临时替换材质与世界设置以确保输出符合要求。同时更新了清理函数以移除新增的临时白色材质。

utils.py

@@ -321,6 +321,145 @@ def _render_normal(operator):
     return _render_with_material(operator, normal_mat, 'normal.png', '法向')
 
 
+def _create_white_material():
+    """Create a flat white emission material for line art background."""
+    mat_name = '__ComfyWhiteMat__'
+    if mat_name in bpy.data.materials:
+        return bpy.data.materials[mat_name]
+
+    mat = bpy.data.materials.new(name=mat_name)
+    mat.use_nodes = True
+    nodes = mat.node_tree.nodes
+    links = mat.node_tree.links
+    nodes.clear()
+
+    emission = nodes.new('ShaderNodeEmission')
+    emission.location = (0, 0)
+    emission.inputs['Color'].default_value = (1, 1, 1, 1)
+    emission.inputs['Strength'].default_value = 1.0
+
+    output = nodes.new('ShaderNodeOutputMaterial')
+    output.location = (200, 0)
+
+    links.new(emission.outputs['Emission'], output.inputs['Surface'])
+    return mat
+
+
+def _render_lineart(operator):
+    """Render line art using Freestyle (black lines on white) for ControlNet Canny."""
+    scene = bpy.context.scene
+    output_dir = _ensure_output_dir()
+
+    converted_obj = _get_converted_obj(scene, operator)
+    if converted_obj is None:
+        return False
+
+    # Save original state
+    vl = scene.view_layers["ViewLayer"]
+    orig_materials = [slot.material for slot in converted_obj.material_slots]
+    orig_use_freestyle = scene.render.use_freestyle
+    orig_vl_use_freestyle = vl.use_freestyle
+    orig_line_thickness = scene.render.line_thickness
+    orig_use_nodes = scene.use_nodes
+    orig_use_compositing = scene.render.use_compositing
+    orig_filepath = scene.render.filepath
+    orig_format = scene.render.image_settings.file_format
+    orig_color_mode = scene.render.image_settings.color_mode
+    orig_film_transparent = scene.render.film_transparent
+    orig_world = scene.world
+
+    # Apply white emission material to all slots
+    white_mat = _create_white_material()
+    if len(converted_obj.material_slots) == 0:
+        converted_obj.data.materials.append(white_mat)
+    else:
+        for i in range(len(converted_obj.material_slots)):
+            converted_obj.material_slots[i].material = white_mat
+
+    # Enable Freestyle
+    scene.render.use_freestyle = True
+    vl.use_freestyle = True
+    scene.render.line_thickness = 1.0
+
+    # Configure lineset: black lines, all relevant edge types
+    fs = vl.freestyle_settings
+    # Save original linesets state
+    orig_lineset_settings = []
+    for ls in fs.linesets:
+        orig_lineset_settings.append({
+            'color': tuple(ls.linestyle.color),
+            'thickness': ls.linestyle.thickness,
+        })
+
+    if len(fs.linesets) == 0:
+        ls = fs.linesets.new('LineSet')
+    else:
+        ls = fs.linesets[0]
+
+    ls.linestyle.color = (0, 0, 0)  # Black lines
+    ls.linestyle.thickness = 1.5
+    ls.select_silhouette = True
+    ls.select_border = True
+    ls.select_crease = True
+    ls.select_edge_mark = True
+
+    # White world background
+    white_world = bpy.data.worlds.new('__ComfyWhiteWorld__')
+    white_world.use_nodes = True
+    bg_node = white_world.node_tree.nodes.get('Background')
+    if bg_node:
+        bg_node.inputs['Color'].default_value = (1, 1, 1, 1)
+        bg_node.inputs['Strength'].default_value = 1.0
+    scene.world = white_world
+    scene.render.film_transparent = False
+
+    # Disable compositor
+    scene.use_nodes = False
+    scene.render.use_compositing = False
+
+    # Setup output
+    out_path = os.path.join(output_dir, 'lineart.png')
+    scene.render.filepath = out_path
+    scene.render.image_settings.file_format = 'PNG'
+    scene.render.image_settings.color_mode = 'RGB'
+
+    # Render
+    bpy.ops.render.render(write_still=True)
+
+    # Restore materials
+    if len(orig_materials) == 0:
+        converted_obj.data.materials.clear()
+    else:
+        for i, mat_orig in enumerate(orig_materials):
+            if i < len(converted_obj.material_slots):
+                converted_obj.material_slots[i].material = mat_orig
+
+    # Restore lineset settings
+    for i, ls_data in enumerate(orig_lineset_settings):
+        if i < len(fs.linesets):
+            fs.linesets[i].linestyle.color = ls_data['color']
+            fs.linesets[i].linestyle.thickness = ls_data['thickness']
+
+    # Restore all settings
+    scene.render.use_freestyle = orig_use_freestyle
+    vl.use_freestyle = orig_vl_use_freestyle
+    scene.render.line_thickness = orig_line_thickness
+    scene.use_nodes = orig_use_nodes
+    scene.render.use_compositing = orig_use_compositing
+    scene.render.filepath = orig_filepath
+    scene.render.image_settings.file_format = orig_format
+    scene.render.image_settings.color_mode = orig_color_mode
+    scene.render.film_transparent = orig_film_transparent
+    scene.world = orig_world
+
+    # Remove temporary world
+    if '__ComfyWhiteWorld__' in bpy.data.worlds:
+        bpy.data.worlds.remove(bpy.data.worlds['__ComfyWhiteWorld__'])
+
+    _add_rendered_image(scene, '线稿', out_path)
+    return True
+
+
 class Comfy_OT_Mvgen_B6229(bpy.types.Operator):
     bl_idname = "comfyui.mvgen_b6229"
     bl_label = "生成多视角视图"
@@ -384,6 +523,9 @@ class Comfy_OT_Mvgen_B6229(bpy.types.Operator):
                     # --- Render Normal Map ---
                     _render_normal(self)
 
+                    # --- Render Line Art ---
+                    _render_lineart(self)
+
             return {"FINISHED"}
 
     def invoke(self, context, _event):
@@ -466,9 +608,10 @@ class Comfy_OT_CleanupMvgen(bpy.types.Operator):
         pcoll = _get_preview_collection()
         pcoll.clear()
 
-        # Remove temp depth material
-        if '__ComfyDepthMat__' in bpy.data.materials:
-            bpy.data.materials.remove(bpy.data.materials['__ComfyDepthMat__'])
+        # Remove temp materials
+        for mat_name in ('__ComfyDepthMat__', '__ComfyWhiteMat__'):
+            if mat_name in bpy.data.materials:
+                bpy.data.materials.remove(bpy.data.materials[mat_name])
 
         # Clear converted name
         if '_comfy_converted_name' in scene: