difference between seed fill and scan line algos for area filling

 Scan Line and Seed Fill are two different algorithms used for polygon filling in computer graphics. Here are the main differences between the two:

1. Approach:

   • Scan Line Algorithm: The scan line algorithm works by scanning each horizontal line of the polygon and determining the intersections of that line with the edges of the polygon. It then fills the region between those intersections.
   • Seed Fill Algorithm: The seed fill algorithm works by selecting a seed point (a point inside the polygon) and recursively filling neighboring pixels until it encounters a boundary.

2. Filling Strategy:

   • Scan Line Algorithm: The scan line algorithm fills a polygon row by row. It scans each row of the polygon from the minimum y-coordinate to the maximum y-coordinate. For each row, it determines the intersections of the scan line with the edges of the polygon and fills the region between those intersections.
   • Seed Fill Algorithm: The seed fill algorithm starts with a seed point and fills all adjacent pixels of the same color until it reaches a boundary or a pixel of a different color. It recursively fills the neighboring pixels using a stack or a queue data structure.

3. Complexity:

   • Scan Line Algorithm: The scan line algorithm is generally more efficient for polygons with a large number of edges. It avoids the need for recursive operations and scans each row of the polygon only once.
   • Seed Fill Algorithm: The seed fill algorithm can be less efficient for complex polygons with a large number of pixels to fill. It requires recursive operations and may process some pixels multiple times.

4. Handling Complex Shapes:

   • Scan Line Algorithm: The scan line algorithm is well-suited for handling complex shapes with concave regions, holes, and self-intersections. It can handle these cases by dividing the polygon into smaller regions and filling them individually.
   • Seed Fill Algorithm: The seed fill algorithm may encounter difficulties in handling complex shapes with concave regions, holes, or self-intersections. It might not be able to fill such regions correctly without additional modifications.

In summary, the scan line algorithm is suitable for handling complex shapes and is more efficient for polygons with a large number of edges. On the other hand, the seed fill algorithm is simpler to implement and can handle simple polygons efficiently but may encounter difficulties with complex shapes.