To auto-smooth edges in Blender, you typically enable the Shade Auto Smooth option, which automatically sets the sharpness of mesh edges based on the angle between neighboring faces.
Understanding Auto Smooth
Auto Smooth in Blender is a convenient way to combine the appearance of smooth shading with sharp edges where needed, without manually marking edges as sharp.
Based on the reference: Shade Auto Smooth adds a Smooth By Angle Modifier to automatically set the sharpness of mesh edges based on the angle between the neighboring faces. Note, the modifier will be pinned to be the last modifier. If disabled, any Smooth By Angle Modifiers are removed.
Essentially, when you enable Auto Smooth, Blender adds a special modifier that analyzes your mesh's face angles. If the angle between two faces is greater than a specified threshold, the edge separating them is treated as sharp; otherwise, it's treated as smooth. This provides a visual effect similar to applying smooth shading to the whole object, but with crisp edges preserved where the surface changes direction sharply (like the corner of a cube).
Steps to Enable Auto Smooth
Here's how to apply auto-smooth to your object:
- Select the object you want to apply auto-smoothing to in the 3D Viewport.
- Go to the Object Data Properties tab in the Properties Editor (it looks like a green triangle).
- Under the Normals panel, expand it if collapsed.
- Check the box next to Auto Smooth.
That's it! Blender will now automatically smooth the shading based on the angle setting.
Adjusting the Angle Threshold
When you enable Auto Smooth, an Angle value appears below the checkbox. This is the crucial setting:
- Angle: This defines the maximum angle between two face normals for their shared edge to be shaded smoothly.
- A lower angle (e.g., 30 degrees) will result in more edges appearing sharp, as even slight changes in surface direction will exceed the threshold.
- A higher angle (e.g., 75 degrees) will result in fewer edges appearing sharp, only preserving sharpness for very dramatic changes in surface direction.
Experiment with this value to get the desired look for your specific model.
Why Use Auto Smooth?
- Efficiency: It saves you the effort of manually marking every sharp edge.
- Flexibility: You can easily adjust the sharpness globally by changing the angle value.
- Clean Workflow: It's part of the object's data, making it easy to manage.
Using Auto Smooth is a standard technique in 3D modeling to achieve a professional look for objects that contain both curved and sharp surfaces.
