initial code for follow curve

utils.py

@@ -956,3 +956,148 @@ def iterate_selector(zone, attr, state, info_attr = None, active_access='active'
                 info = getattr(active_item, info_attr)
 
         return info, bottom
+
+# -----------------
+### Curve handle
+# -----------------
+
+def create_curve(location=(0,0,0), direction=(1,0,0), name='curve_path', enter_edit=True, context=None):
+    '''Create curve at provided location and direction vector'''
+
+    ## option to create nurbs instaed of bezier ?
+
+    context = context or bpy.context
+    
+    ## using ops (dirty)
+    # bpy.ops.curve.primitive_bezier_curve_add(radius=1, enter_editmode=enter_edit, align='WORLD', location=location, scale=(1, 1, 1))
+    # curve = context.object
+    # curve.name = 'curve_path'
+    # # fast straighten
+    # bpy.ops.curve.handle_type_set(type='VECTOR')
+    # bpy.ops.curve.handle_type_set(type='ALIGNED')
+    # bpy.ops.transform.translate(value=(1, 0, 0), orient_type='LOCAL', 
+    # orient_matrix=((1, 0, 0), (0, 1, 0), (0, 0, 1)), orient_matrix_type='LOCAL', 
+    # constraint_axis=(True, False, False), mirror=True, use_proportional_edit=False)
+    
+    ## using data
+    curve_data = bpy.data.curves.new(name, 'CURVE') # ('CURVE', 'SURFACE', 'FONT')
+    curve_data.dimensions = '3D'
+    curve_data.use_path = True
+
+    curve = bpy.data.objects.new(name, curve_data)
+    spl = curve_data.splines.new('BEZIER') # ('POLY', 'BEZIER', 'NURBS')
+    spl.bezier_points.add(1) # One point already exists
+    for i in range(2):
+        spl.bezier_points[i].handle_left_type = 'VECTOR' # ('FREE', 'VECTOR', 'ALIGNED', 'AUTO')
+        spl.bezier_points[i].handle_right_type = 'VECTOR'
+    spl.bezier_points[1].co = direction
+    
+    # Back to aligned mode
+    for i in range(2):
+        spl.bezier_points[i].handle_right_type = spl.bezier_points[i].handle_left_type = 'ALIGNED'
+
+    # Select second point
+    spl.bezier_points[1].select_control_point = True
+    spl.bezier_points[1].select_left_handle = True
+    spl.bezier_points[1].select_right_handle = True
+
+    # link
+    context.scene.collection.objects.link(curve)
+
+    # curve object settings
+    curve.location = location
+    curve.show_in_front = True
+
+    # enter edit
+    if enter_edit and context.mode == 'OBJECT':
+        curve.select_set(True)
+        context.view_layer.objects.active = curve
+        bpy.ops.object.mode_set(mode='EDIT', toggle=False) # EDIT_CURVE
+
+    ## set viewport overlay visibility for better view
+    if context.space_data.type == 'VIEW_3D':
+        context.space_data.overlay.show_curve_normals = True
+        context.space_data.overlay.normals_length = 0.2
+
+    return curve
+
+def get_direction_vector_from_enum(string) -> Vector:
+    orient_vectors = {
+    'FORWARD_X' : Vector((1,0,0)),
+    'FORWARD_Y' : Vector((0,1,0)),
+    'FORWARD_Z' : Vector((0,0,1)),
+    'TRACK_NEGATIVE_X' : Vector((-1,0,0)),
+    'TRACK_NEGATIVE_Y' : Vector((0,-1,0)),
+    'TRACK_NEGATIVE_Z' : Vector((0,0,-1))
+    }
+    return orient_vectors[string]
+
+def orentation_track_from_vector(input_vector) -> str:
+    '''return closest world track orientation name from passed vector direction'''
+    orient_vectors = {
+    'FORWARD_X' : Vector((1,0,0)),
+    'FORWARD_Y' : Vector((0,1,0)),
+    'FORWARD_Z' : Vector((0,0,1)),
+    'TRACK_NEGATIVE_X' : Vector((-1,0,0)),
+    'TRACK_NEGATIVE_Y' : Vector((0,-1,0)),
+    'TRACK_NEGATIVE_Z' : Vector((0,0,-1))
+    }
+
+    orient = None
+    min_angle = 10000
+    for track, v in orient_vectors.items():
+        angle = input_vector.angle(v)
+        if angle < min_angle:
+            min_angle = angle 
+            orient = track
+
+    return orient
+
+def create_follow_path_constraint(ob, curve, follow_curve=False):
+    '''return create constraint'''
+    # # Clear bone follow path constraint 
+    exiting_fp_constraints = [c for c in ob.constraints if c.type == 'FOLLOW_PATH']
+    for c in exiting_fp_constraints:
+        ob.constraints.remove(c)
+
+    # loc = ob.matrix_world @ ob.matrix.to_translation()
+    if ob.location != (0,0,0):
+        old_loc = ob.location
+        ob.location = (0,0,0)
+        print(f'ob moved from {old_loc} to (0,0,0) to counter follow curve offset')
+
+    const = ob.constraints.new('FOLLOW_PATH')
+    const.target = curve
+    if follow_curve:
+        const.use_curve_follow = True
+    return const
+
+    ## on_bones:
+    # prefs = get_addon_prefs()
+    # root_name = prefs.tgt_bone
+    # root = ob.pose.bones.get(root_name)
+
+    # if not root:
+    #     return ('ERROR', f'posebone {root_name} not found in armature {ob.name} check addon preferences to change name')
+
+    # # Clear bone follow path constraint 
+    # exiting_fp_constraints = [c for c in root.constraints if c.type == 'FOLLOW_PATH']
+    # for c in exiting_fp_constraints:
+    #     root.constraints.remove(c)
+
+    # # loc = ob.matrix_world @ root.matrix.to_translation()
+    # if root.name == ('world', 'root') and root.location != (0,0,0):
+    #     old_loc = root.location
+    #     root.location = (0,0,0)
+    #     print(f'root moved from {old_loc} to (0,0,0) to counter follow curve offset')
+
+    # const = root.constraints.new('FOLLOW_PATH')
+    # const.target = curve
+    # # axis only in this case, should be in addon to prefs
+
+    # ## determine which axis to use... maybe found orientation in world space from matrix_basis ?
+    # root_world_base_direction = root.bone.matrix_local @ get_direction_vector_from_enum(bpy.context.scene.anim_cycle_settings.forward_axis)
+    # const.forward_axis = orentation_track_from_vector(root_world_base_direction) # 'TRACK_NEGATIVE_Y' # bpy.context.scene.anim_cycle_settings.forward_axis # 'FORWARD_X'
+    # print('const.forward_axis: ', const.forward_axis)
+    # const.use_curve_follow = True
+    # return curve, const