Painter's Algorithm

CORE DEFINITION

The Painter's Algorithm, also known as priority fill, is a method for solving the visibility problem in 3D computer graphics. When projecting a 3D scene onto a 2D plane, it is necessary to determine which polygons are visible and which are not. The Painter's Algorithm represents a simple-minded painter who first paints the distant parts of the scene, then covers them with nearer parts. The algorithm first sorts the polygons in the scene by depth, then draws them in order. This method typically covers the invisible parts, thus solving the visibility problem. In some cases, the Painter's Algorithm may fail to solve the visibility problem. In this example, polygons A, B, and C overlap each other, and we cannot determine which polygon is on top and which is below, nor can we determine when two polygons intersect in 3D space. In such cases, methods must be used to split and sort these polygons. The Newell algorithm proposed in 1972 is one such method for splitting similar polygons, and many solutions have been proposed in the field of computational geometry.