Coverage for src/meshpy/core/node.py: 98%

1# The MIT License (MIT) 

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3# Copyright (c) 2018-2025 MeshPy Authors 

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12# The above copyright notice and this permission notice shall be included in 

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21# THE SOFTWARE. 

22"""This module implements the class that represents one node in the Mesh.""" 

23 

24import numpy as _np 

25 

26from meshpy.core.base_mesh_item import BaseMeshItem as _BaseMeshItem 

27 

28 

29class Node(_BaseMeshItem): 

30 """This object represents one node in the mesh.""" 

31 

32 def __init__(self, coordinates, *, is_middle_node=False, **kwargs): 

33 super().__init__(**kwargs) 

34 

35 # Coordinates of this node. 

36 self.coordinates = _np.array(coordinates) 

37 

38 # If this node is at the end of a line or curve (by default only those 

39 # nodes are checked for overlapping nodes). 

40 self.is_end_node = False 

41 

42 # If the node is in the middle of a beam element. 

43 self.is_middle_node = is_middle_node 

44 

45 # Lists with the objects that this node is linked to. 

46 self.element_link = [] 

47 self.node_sets_link = [] 

48 self.element_partner_index = None 

49 self.mesh = None 

50 

51 # If this node is replaced, store a link to the remaining node. 

52 self.master_node = None 

53 

54 def get_master_node(self): 

55 """Return the master node of this node. 

56 

57 If the node has not been replaced, this object is returned. 

58 """ 

59 

60 if self.master_node is None: 

61 return self 

62 else: 

63 return self.master_node.get_master_node() 

64 

65 def replace_with(self, master_node): 

66 """Replace this node with another node object.""" 

67 

68 # Check that the two nodes have the same type. 

69 if not isinstance(self, type(master_node)): 

70 raise TypeError( 

71 "A node can only be replaced by a node with the same type. " 

72 + f"Got {type(self)} and {type(master_node)}" 

73 ) 

74 

75 # Replace the links to this node in the referenced objects. 

76 self.mesh.replace_node(self, master_node) 

77 for element in self.element_link: 

78 element.replace_node(self, master_node) 

79 for node_set in self.node_sets_link: 

80 node_set.replace_node(self, master_node) 

81 

82 # Set link to master node. 

83 self.master_node = master_node.get_master_node() 

84 

85 def unlink(self): 

86 """Reset the links to elements, node sets and global indices.""" 

87 self.element_link = [] 

88 self.node_sets_link = [] 

89 self.mesh = None 

90 self.i_global = None 

91 

92 def rotate(self, *args, **kwargs): 

93 """Don't do anything for a standard node, as this node can not be 

94 rotated.""" 

95 

96 def dump_to_list(self): 

97 """Return a list with the legacy string representing this node.""" 

98 

99 return { 

100 "id": self.i_global, 

101 "COORD": self.coordinates, 

102 "data": {"type": "NODE"}, 

103 } 

104 

105 

106class NodeCosserat(Node): 

107 """This object represents a Cosserat node in the mesh, i.e., it contains 

108 three positions and three rotations.""" 

109 

110 def __init__(self, coordinates, rotation, *, arc_length=None, **kwargs): 

111 super().__init__(coordinates, **kwargs) 

112 

113 # Rotation of this node. 

114 self.rotation = rotation.copy() 

115 

116 # Arc length along the filament that this beam is a part of 

117 self.arc_length = arc_length 

118 

119 def rotate(self, rotation, *, origin=None, only_rotate_triads=False): 

120 """Rotate this node. 

121 

122 By default the node is rotated around the origin (0,0,0), if the 

123 keyword argument origin is given, it is rotated around that 

124 point. If only_rotate_triads is True, then only the rotation is 

125 affected, the position of the node stays the same. 

126 """ 

127 

128 self.rotation = rotation * self.rotation 

129 

130 # Rotate the positions (around origin). 

131 if not only_rotate_triads: 

132 if origin is not None: 

133 self.coordinates = self.coordinates - origin 

134 self.coordinates = rotation * self.coordinates 

135 if origin is not None: 

136 self.coordinates = self.coordinates + origin 

137 

138 

139class ControlPoint(Node): 

140 """This object represents a control point with a weight in the mesh.""" 

141 

142 def __init__(self, coordinates, weight, **kwargs): 

143 super().__init__(coordinates, **kwargs) 

144 

145 # Weight of this node 

146 self.weight = weight 

147 

148 def dump_to_list(self): 

149 """Return a list with the legacy string representing this control 

150 point.""" 

151 

152 return { 

153 "id": self.i_global, 

154 "COORD": self.coordinates, 

155 "data": {"type": "CP", "weight": self.weight}, 

156 }