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This VOP computes the amount of surface curvature, with white in convex areas, black in concave areas and 50% gray in flat areas. This is useful for masking wear like scratches and dents, which often happen on raised edges.
Derivatives for polygonal meshes are not continuous, which results in a "faceted" look. To evaluate smooth curvature for meshes you should enable Smooth. However, Smooth is ignored and relies on fine dicing to generate smooth look, when rendering subdivision mesh. If you see faceting with subdivision mesh, increasing Shading Quality or reducing Dicing Flatness will help.
Input surface point. If not connected the global variable of the same name is used.
Input surface normal. If not connected the global variable of the same name is used.
Selects between various curvature properties. Gaussian is the product of the principal curvatures. Mean is half the sum of the principal curvatures.
Selects the output space of the curvature value.
-1 to 1 uses a mid-point of
0.0, with convex areas from
0.0 > 1.0 and concave areas from
-1.0 > 0.0.
0 to 1 uses a mid-point of
0.5, with convex areas from
0.5 > 1.0 and concave areas from
0.0 > 0.5.
Enables smooth evaluation of curvature for polygonal meshes. Smooth evaluation also ignores any displacement the material may have on it.
Determines how small a change in curvature is considered when shading the gradient.
Multiplies the output curvature value. If you are seeing any curvature shading you should increase this value until the gradient is visible.
This acts as a contrast control over the gradient, with values higher and lower than
0.5 resulting in more and less contrast.
Varies the bias by a pattern. This is useful for breaking up smooth areas of the gradient. It should be mapped with a greyscale pattern, in the /nodes/vop/0,1 range.
Output curvature value.
This example shows how the curvature vop can be added to a shader network to add a worn or distressed look to your material.
The following examples include this node.