At present the only way to do this solely with RailClone would be to control the material IDs on the source objects. This quicktips tutorial shows how this could be done to create a tiles gradient.
Alternatively I have had some success using Crossmap. I've attached a sample file to illustrate but the basic workflow is:
- Use UV channel 1 for the normal tile's mapping
- Use UV channel 2 for the pattern's mapping
- In RailClone use the automatic box mapping feature to set the size and scale of the pattern. Note that it is set to map channel 2.
- In Crossmap, set Image Selection
to Use Input Map
- Set Image Distribution
to Rail Clone
- Add your coloured tile maps to Crossmap in the usual way. Remember that Crossmap automatically derives an averaged colour for these that's used to match the pattern, but these can be edited manually for different effects.
- Add your pattern image to the Input Map > Source slot
. The bitmaps will be selected based on the colours of this map.
- Enable Nearest Color Match
Hopefully that works for you. I would also like to mention that RailClone 3 will include a new colour map that will allow you to tint tiles based on a bitmap applied to a surface which could be useful for situations like this.