Offsetting The Rotation Pivot For Circular Arrays In Blender
Centering Objects for Circular Array Duplicates
When creating circular arrays of duplicated objects in Blender, it is often desirable to offset the copies radially around a central pivot point. This allows precise positioning of the copies in a circular formation. To effectively utilize offsets with circular arrays, the rotation origin must first be properly established.
The most reliable method is to explicitly set the 3D cursor as the rotation pivot before adding the array modifier. The cursor can be snapped to the exact geometry origin of an object using shortcut keys. This centers the rotation for optimum control when offsetting the arrayed copies.
Defining the Rotation Pivot Point
Blender allows flexibility in defining the pivot point for rotations and scaling. By default, the median point of an object’s geometry becomes the central origin. However, the cursor can be used to take precise control of this origin for arrays.
When adding an array modifier, Blender rotates copies around the set pivot point. Without adjusting this point, copies may not generate evenly around the center. Setting the 3D cursor as the pivot is therefore essential for circular arrays with offset.
Snapping the Cursor to the Geometry Origin
The 3D cursor can be quickly snapped to the exact geometry origin of an object using shortcut keys. With the object selected, press Shift + S and choose “Selected to Cursor” from the menu. Alternatively, choose “Cursor to Selected” to snap the object itself to the cursor location.
This method accurately centers the rotation pivot for optimum control. The origin now matches the median geometry center rather than the object’s displaced center. Offsetting the array around this point keeps copies evenly spaced.
Setting the Cursor as the Rotation Origin
With the cursor snapped to the geometry origin, it must be explicitly set as the rotation pivot point. The Transform Orientation in the 3D viewport controls the pivot used for transformations.
By default, this matches the median point of the selection. Change it to “Cursor” so all rotations occur precisely around the cursor instead. Now arrayed copies will generate evenly around the central point.
Creating the Circular Array Modifier
Once the appropriate pivot point is set with the 3D cursor, the Circular Array modifier can be added. This dynamically generates rotated instances of the base object in a circular formation.
Add a Circular Array modifier in the Object Modifiers properties. Adjustments can then be made to parameters like Count, Radial Offset, and Spin Angle to control the duplication.
Arraying Objects Around the Cursor
The cursor now marks the central point for arraying duplicate copies. With “Cursor” set as the Transform Orientation, all rotations occur around this fixed pivot when Blender generates the copies.
Spacing of individual elements will rotate evenly around the cursor when adding circular arrays this way. Offset and spin adjustments to the array can fine-tune the placement as needed.
Offset Options for Circular Array Duplicates
The Circular Array modifier includes options for radially offsetting copies relative to each other. An Offset value slides duplicates apart or together tangentially around the spin angle specified.
Positive values offset adjacent duplicates moving counterclockwise. Negative values offset copies moving clockwise instead. An offset of zero generates copies evenly spaced and touching.
Radial Rotating Copies for Precise Positioning
The rotational angle that Blender uses when spinning arrayed duplicates can also be adjusted. The Spin value rotates copies in degrees around the set pivot point through each instance in the array.
Combined with offsetting settings, the spin angle provides further control over radial positioning of copies. Spins rotated 180 degrees generate mirroring patterns to each side of the object for example.
Animating the Offset Factor Over Time
The circular array modifier includes options for animating the offset over time. This causes copies to dynamically adjust positions in a spinning motion relative to each other.
By keyframing different Offset values, instances can shift to precise spots at certain times. Animated arrays build complex spinning structures, machines, and gear systems.
Example Code for Circular Arrays with Offset
The following Python code demonstrates creating a circular array with options for offsetting individual copies in the radial rotation:
import bpy
from math import radians
# Set cursor as pivot point
bpy.ops.view3d.snap_cursor_to_selected()
bpy.context.space_data.transform_orientation = 'CURSOR'
# Add cube and apply circular array modifier
bpy.ops.mesh.primitive_cube_add()
myCube = bpy.context.object
myArray = myCube.modifiers.new("MyArray", 'ARRAY')
myArray.fit_type = 'FIXED_COUNT'
myArray.count = 8
# Set circular array parameters
myArray.curve = None
myArray.relative_offset_displace = (0, 0, 0)
myArray.use_constant_offset = True
myArray.use_relative_offset = False
myArray.start_cap = None
myArray.end_cap = None
# Rotate copies in circle
myArray.start_angle = 0
myArray.angle = radians(45)
# Offset individual copies
myArray.constant_offset_displace = (0, 1, 0)
bpy.ops.object.select_all(action='DESELECT')
This script snaps the cursor to the selected object, sets it as the rotation pivot point, adds a cube with 8 array duplicates, rotates copies in a 45 degree circular formation, and offsets them by +1 unit on the Y axis for even radial spacing.
