Catenary curves are used in Blender to add hanging wires, cables, ropes or other curves in a scene. The catenary curve will hang, or “droop” between the origin points of two objects. This is how to add a hanging curve in Blender with catenary curves.
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What is a Catenary Curve in Blender?
A catenary curve is a curve that follows a mathematical formula to hang or “droop” between two points. In Blender, we can add catenary curves if we’ve enabled the Extra Curve Objects add-on in the User Preferences.
A catenary curve will hang between the origin points of two objects. These can be used to create hanging wires or cables in a scene. The drooping curve can be adjusted to hang lower or be tighter in the curve’s settings.
How to Add a Hanging Curve in Blender
To make a hanging (catenary) curve, we must first activate the Extra Curve Objects add-on which comes pre-installed in Blender. It is not activated by default.
Step 1: Activate the Extra Curve Objects Add-On
Go to the User Preferences and in the add-on tab, find the add-on labeled “Add Curve: Extra Objects.” Check the box to the left to activate it.
Step 2: Select Two Objects
Select exactly two objects from which you want the curve to hang. If you have more than two objects selected, the curve will be hung from the last two selected. The origin points of these objects will be the end points of the curve.
Once we create the hanging curve, it will not (by default) be connected to these objects. Moving the objects in the future will not affect the shape or location of the curve.
Step 3: Add the Catenary Curve
With two objects selected, hover in the 3D viewport and press “Shift + A” to add a new object. Choose “Curve” and go toward the bottom of the available options to find “Knots.” From the knots category, choose “Catenary.”
The catenary curve will be added and will hang between the origin points of the two selected objects.
Step 4: Adjust the Catenary Curve
After adding the catenary curve, we adjust its settings in the operator panel which appears at the bottom left corner of the 3D viewport.
These adjustments can only be made after we add the curve and before we conduct another operation. They will be locked into place once we do another action in Blender (although some can still be adjusted in the curve properties panel).
The steps setting controls how many bezier curve points the catenary curve will have.
The “A” Setting
The “A” setting controls how far the catenary curve will hang. Lowering the value will cause the hanging curve to droop lower (along the z axis). Increasing this value will tighten the curve and remove slack from our hanging cable, wire or rope.
The bevel radius setting adds thickness to the curve to make it three dimensional. By default, it will have a perfectly round profile. Increasing the bevel radius will increase the thickness of the curve.
The bevel resolution is how many segments the beveled profile will have. Increasing this makes the cable more smooth but will add additional geometry to the object.
Additional settings are available to add extrusion, tilt and twisting to the curve. These you’ll just have to play around with. In general, I’ve found they work better with a lower step count.
Hanging Curves and Cables with Cablerator
Using the catenary curve in Blender is completely free. For a lot more functionality and to add multiple cables and wires in a scene at the same time, I prefer using the paid add-on Cablerator. It’s pretty affordable and provides a lot of functionality.
Take a look at Cablerator on Blender Market. The creator has some pretty impressive videos showing what it can do.
Adding hanging curves, wires, ropes and cables in a scene can provide a lot of detail fairly easily. Catenary curves are a way to droop a hanging curve between two objects. We can then adjust how the curve hangs as well as its thickness and how it twists.
The paid add-on Cablerator gives us a lot of additional functionality to easily add cables and wires to a scene.
I hope this was helpful. Play around with catenary curves in your renders. Have a look around the site and on my YouTube channel for more Blender tutorials. Stay creative!
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