You need to be able to touch the color in your material:
- in your material make the color an exposed parameter. make a material instance and access one of it’s properties in a blueprint
- If you make a material parameter collection (MPC) and point your material to the collection, you can change the MPC value directly and it will flow into the material automagically
- you can do the same thing as a custom primitive data, it’s like the MPC but the values are stored on the mesh directly
Once you have one of these set up, you can do whatever processes/maths on your material parameters and it should just-flow back in to the material.