Curves are special objects in blender, which allow you to create smooth mesh deformations, can be used to animate objects along a path and are even used in blenders hair and particle systems. They play an essential role in 3D modeling and animation and can be challenging to master. But once you've used them a couple of times, you'll find yourself using them in almost every project. In Blender, you can create curves just like you create meshes. Different curves serve the same purpose: to create a path using control points. The only difference are the handles you use to deform the path. Your choice of curve depends on personal preference; you can achieve the same results with any curve. When you enter edit mode for a curve, you'll see the different control points. By moving these points, like you move vertices, you can influence the path. You can add more control points by subdividing when you select two control points, right-click, and choose subdivide. Alternatively, you can select a control point and press E to extrude You can also delete control points as usual by pressing X. Each control point has handles that allow you to manipulate the shape of the curve. There are four handle types in Blender: Automatic, Vector, Aligned, and Free. You can switch between handle types by selecting a control point and pressing the V key or by using the toolbar options in the Control Points menu. Automatic handles adjust themselves based on surrounding points, Vector handles create sharp corners, Aligned handles maintain smooth curves, and Free handles allow you to manipulate each side of the handle independently. Another useful function is Smooth, which you can find under Control-Points -> Smooth. Each Curve has a direction. You can view the direction by activating "Draw Normals" in the overlays panel while in edit mode for the curve. To invert the direction, select at least one control point and click on segments - switch direction. The main use cases for a curve are to deform a mesh along a curve, create a mesh along a curve, or use the curve as a path for objects to move along in animation. Let’s start with the curve modifier: The curve modifier is used to deform a mesh along a curve. Using the curve modifier in Blender can be tricky, as there are many potential mistakes to make. Both objects must share the same origin, have the correct axis chosen, and be properly aligned. However, there's a simple recipe to make it work every time. First, ensure your object is located at the world origin, pointing upwards, and that you have applied the rotation by pressing Ctrl+A. Then, create a curve and enter edit mode. Move the control points to match your mesh. Add the curve modifier to your mesh, select the previously created curve, and choose the Z-Axis. If the direction is wrong, simply invert it as shown before. You can now play around with the curve to deform your mesh. If you want to move your mesh to another position, select both objects and move them, or select all control points in edit mode of the curve and move them. Moving only one object will cause problems. There are 2 additional useful features you need to know. You can tilt control points in the transform window or by pressing Ctrl+T And you can increase the radius of a control point, thus increasing the geometry with Alt+S Let's continue with creating a mesh along a curve. Every curve can be given a profile to create geometry. To do so, go to the Object Data Properties, Geometry, and adjust the depth in the Bevel dropdown. You can adjust the resolution of the geometry in both directions. The first is located here and adjusts the number of vertices for the cross-section. The second is located here and defines the resolution between two control points. You can adjust the profile of your geometry here playing around with this curve. You can also use another curve to define the bevel of your geometry. Sometimes, you may want to convert a curve into a mesh for further editing or texturing. To do so, first select the curve object, and in Object mode go to Object > Convert and choose Mesh. This will convert the curve into a mesh object that you can edit just like any other mesh in Blender. The next use case is guiding an object along a path in animation. For this, let's create a new curve and adjust it to make a little twist. Then, create a mesh Go to "Object Constraint Properties," select "Follow Path," choose your curve as the target, select "Follow Curve" to make your object tilt along the curve, click on "Animate Path," and hit play! When you go to the Object Data Properties of the curve and expand the "Path Animation" tab, you can adjust the length of the animation. and expand the "Path Animation" tab, you can adjust the length of the animation. Let's create an example configuration. I want my animation to start at 100 frames, so I have to set the offset of the constraint to 100. And to prevent my object from leaving the curve, I can turn on "Clamp" in the path animation. Using this concept, you can create impressive camera tracking shots, make characters run along a path, and much more! If you want to practice using curves, especially in combination with other modifiers, feel free to check out my braided leather wrapping tutorial. This exercise will help you familiarize yourself with curves and their potential applications in Blender.
