ramps and fold colour change

hello, im trying to build a material (node network probably) that simulates aged metal such as a bronze statue… where the concave folds are blueish and the convex folds are brown/orange. a polish on particuraly flat areas would be ideal…

so far i’ve been able to build only things that rely on simple normal manipulation, but for this, I think i need to calculate and use the angle between normals, to account for the convex/concave issue.

does anyone have a few clues how to make this?

apologies if this as been discussed before, im not really sure what to search for here

It’s probably more work than you want to do, but a good effect can be achieved by UV unwrapping your model, then baking Ambient Occlusion into a texture map. In this image file, then, you’ll have “fold” areas dark, with “non-fold” areas light. You can use this map as either a mask for different textures within a material, a way of blending between two node materials, or the basis for a fully painted color image map.

thats a cool idea hankyman, the only issue is i want this shader as a sculpting tool - so i want to build a glsl shader, but i do definitely like your idea - very cool…

hmmm…again some excellent tips to have in my knowledge. thanks for sharing your knowledge.