Decorating your models is an important part of Folding, so I need to be able to add overlay textures in a way that doesn't destroy the lovely papery look of the thing. The trouble is, you can get very close to your model, particularly if it's intricately folded, and there is a limit to how high a resolution the textures can be. If you zoom in and are faced with jagged edges and bilinear filtering artefacts, the game stops saying 'I'm a piece of paper' and starts saying 'I'm just an app'.

There's a trick for rendering decals in games, where the blurry filtered texture is thresholded to give a sharp outline (a version of this technique is described here). I use a variation of this which handles coloured decals: I first saturate the colours in the source texture, and store the intensity in the alpha channel so that I can reconstruct the original colour. When I come to render it on the paper, I use the paper's detail heightmap to threshold the decal's alpha value. This means that from a distance the decal averages out to its original colour, but close up you see solid ink which has stuck to paper fibres and is missing from some of the hollows. And instead of blurry jagged edges, you get papery fibrous ink blotches.

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I've exchanged one low resolution artefact for a different low resolution artefact - but it is now, at least, one which is consistent with the world it's in.