We use the noise texture to vary the color of the object, with a sharp transition between the base color and the paint color. We'll use either the base color or paint color as the diffuse reflectivity of the shading model. If the noise value is above a certain threshold, we'll use the paint color; otherwise, we'll use the base color of the object.
There are a couple of uniform variables that define the parameters of the paint spatters:
PaintColor: The color of the paint spatters
Threshold: The minimum noise value where a spatter will appear
Create a noise texture with high-frequency noise.
Make your noise texture available to the...