Blender: 3D rotation arrow

blender_create_3d_rotation_arrow.py

import bpy
import math

def create_3d_rotation_arrow():
    # Parameters to tweak the look of your arrow
    radius = 2.0             # Radius of the overall circle
    thickness = 0.2          # Thickness of the curved pipe
    arrow_radius = 0.5       # Width of the arrowhead
    arrow_length = 1.0       # Length of the arrowhead
    start_angle = 0.0
    end_angle = math.radians(280) # 280-degree sweep leaves a nice gap
    segments = 32

    # 1. Create the curved body (NURBS path)
    curve_data = bpy.data.curves.new(name='RotationCurveData', type='CURVE')
    curve_data.dimensions = '3D'
    curve_data.bevel_depth = thickness
    curve_data.bevel_resolution = 6
    curve_data.fill_mode = 'FULL'

    spline = curve_data.splines.new(type='NURBS')
    spline.points.add(segments - 1)
    
    for i in range(segments):
        factor = i / (segments - 1)
        angle = start_angle + (end_angle - start_angle) * factor
        
        # Calculate X/Y along a circle
        x = radius * math.cos(angle)
        y = radius * math.sin(angle)
        
        # Set point coordinates (x, y, z, weight)
        spline.points[i].co = (x, y, 0, 1.0)
        
    spline.use_endpoint_u = True

    # Link curve to the scene
    curve_obj = bpy.data.objects.new('RotationArrow_Body', curve_data)
    bpy.context.collection.objects.link(curve_obj)

    # 2. Create the Arrowhead (Cone)
    bpy.ops.mesh.primitive_cone_add(
        vertices=32, 
        radius1=arrow_radius, 
        depth=arrow_length, 
        location=(0, 0, 0)
    )
    arrowhead = bpy.context.active_object
    arrowhead.name = 'RotationArrow_Head'

    # 3. Position and Rotate the Arrowhead
    # Calculate tangent vector at the end of the curve
    tangent_angle = end_angle + math.pi / 2
    
    # Calculate exactly where the curve ends
    end_x = radius * math.cos(end_angle)
    end_y = radius * math.sin(end_angle)
    
    # Offset the cone so its flat base sits flush against the end of the curve
    # (Since a cone's origin is at its center, we move it forward by half its length)
    offset_x = (arrow_length / 2.0) * math.cos(tangent_angle)
    offset_y = (arrow_length / 2.0) * math.sin(tangent_angle)
    
    arrowhead.location = (end_x + offset_x, end_y + offset_y, 0)
    
    # Rotate cone to follow tangent. 
    # Default cone points Z UP. We rotate Y by 90 to lay it flat, then Z by the tangent angle.
    arrowhead.rotation_euler = (0, math.pi / 2, tangent_angle)

    # 4. Create and Apply the Blue Material
    mat = bpy.data.materials.new(name="RotationBlue")
    mat.use_nodes = True
    bsdf = mat.node_tree.nodes.get("Principled BSDF")
    if bsdf:
        # Hex translation of the bright blue UI color
        bsdf.inputs['Base Color'].default_value = (0.05, 0.45, 1.0, 1.0) 
        bsdf.inputs['Roughness'].default_value = 0.3
        
    curve_obj.data.materials.append(mat)
    arrowhead.data.materials.append(mat)

    # Smooth out the arrowhead's shading
    bpy.ops.object.shade_smooth()

    # Parent the arrowhead to the curve so you only have to move one object around
    arrowhead.parent = curve_obj
    
    # Make the final group active and selected
    bpy.context.view_layer.objects.active = curve_obj
    curve_obj.select_set(True)

# Run the function
create_3d_rotation_arrow()