Round Edges Shading tutorial

Important:

You should use the round_corners shader instead.



_{Rounded edges using the curvature shader (convex and concave)}	_{without curvature}

This short tutorial shows how to create a rounded corner shading effect on the corner edges of objects. This can be useful for creating tiny bevels on your objects without having to model them manually.

The scene file with shader can be downloaded here.

Note:

This is a fake 'hack' shading effect and has many limitations. For example, the effect breaks down if the curvature.radius is too high. Also, the camera should not be placed too close to the beveled object, otherwise the illusion will be broken.

Start off by assigning a standard_surface shader to the object(s).
Create a bump2d and connect it to the normal parameter of the standard_surface shader. We will effectively be using the bump2d shader to push the normals on the edges of the object.

Convex Edges



_{convex curvature only}	_{without convex curvature}

Connect a composite shader to the bump_map parameter of the bump2d shader and make sure that the operation is set to multiply.
Connect a complement map to the B input of the composite shader.
Connect a curvature shader to the input of the Complement shader and set its output to convex. Increase the radius to a small amount like 0.3 (increase it too much and the bevel effect will look unconvincing).

_{Convex edges curvature shading network}

Concave Edges



_{concave curvature only}	_{without concave curvature}

Now we need to add the inverse effect to the cavities using the convex output of another curvature shader and 'screen' it on top of the current shading network.

To have both concave and convex edges work, the A input on the first composite (multiply) is set to 50% grey (with invert edges ( complement ). The white cavities (Convex) is then 'screened' on top of that so that the normals are pushed on the edges and pulled up on the cavities.

Create another composite map and connect it in between the bump2d and the composite (multiply). Set its operation to screen. We will use this to screen another curvature map onto the convex shading network.
Duplicate the curvature shader and set its output to convex. Connect it to the B input of the composite (screen).

The final shader network should look like the following.

_{Final shader network. Convex curvature shader screened onto concave curvature shader}