Especially for old painted objects you would want some edges to be worn out and show the metal below the paint layer.
In order to get a realistic result you would have to paint it by hand or use some third party software, like substance painter.
In this tutorial i will show you how to get worn edges using only Cinema 4D components.
Step 1: creatig basic mask
By adding an ambient occlusion shader to the luminance channel of a material and setting it to Invert Direction, will make the the edges of the Model ocluded. Already we see all the edges selected. If you invert the colors and tweak them a bit, you can create a high contrast render from the AO.
Step 2: add realism using Scratchmaps
So to make things look more realistic we want to apply a scratch map to thhe AO layer. A scratchmap is a black and white image of sctraches. Such images can be found online. I have mine from a site called Poliigon.com
After adding the image, your edges should have actual straches on them.
Step 3: using the mask
To actually use our mask simply drop it into an alpha channel of your metal material and you should be good to go. Then Aplly the painted and metal meterial to your desired object.
It really is A simple and great way to get worn edges procedurally without painting anything.
To make our object even more realistic looking we can add some more dirt, hand smudges or stains. Whatever suits our object. Learn more about this here
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