Abstract: We present a method for rendering 3D paintings by compositing brush strokes embedded in space. The challenge in compositing 3D brush strokes is reconciling conflicts between their z-order in 3D and the order in which the strokes were painted, while maintaining temporal and spatial coherence. Our algorithm smoothly transitions between compositing closer strokes over those farther away and compositing strokes painted later over those painted earlier. It is efficient, running in O(n log n) time, and simple to implement. We demonstrate its effectiveness on a variety of 3D paintings.