Abstract: We present a stable shading method and a procedural shading model that enables real-time rendering of sub-pixel glints and anisotropic microdetails resulting from irregular microscopic surface structure to simulate a rich spectrum of appearances ranging from sparkling to brushed materials. We introduce a biscale Normal Distribution Function (NDF) for microdetails to provide a convenient artistic control over both the global appearance as well as over the appearance of the individual microdetail shapes, while efficiently generating procedural details. Our stable rendering approach simulates a hierarchy of scales and accurately estimates pixel footprint at multiple levels of detail to achieve good temporal stability and antialiasing, making it feasible for real-time rendering applications.