Scan Converting Polygons by Hand:

Sample Point Algorithm

The algorithm demonstrated here assigns a pixel to a polygon if the lower left corner of the pixel is inside the polygon. This corner is considered the sample point. Great care is taken at sample points which lie on an edge or vertex of a polygon to ensure that no two non-overlapping polygons share a pixel.

For this demo, polygons can be drawn one vertex at a time, the most recent can be deleted, or all polygons can be deleted, but no other editing operations are supported. With snapping mode on (the default), we can draw polygons with shared vertices and observe that (hopefully) none of the pixels overlap.

Viewing commands:

Clicking the mouse in the applet window adds a vertex to the current polygon.

The pseudo-code for this algorithm is also available.