This paper introduces novel GPU-based rendering techniques for digital painting and animation to bridge the gap between raster and vector stroke representations. We propose efficient rendering methods for vanilla, stamp, and airbrush strokes that integrate the expressiveness of raster-based textures with the ease of real-time editing. Based on our stroke representation, we implement an open-source prototype drawing system with a vector fill feature, demonstrating that our techniques can enhance the expressiveness, efficiency, and edibility of digital drawing. Our work can serve as a foundation for future research on vector-based and GPU-accelerated rendering techniques in industrial-level brush engines.