Rasterization

Scanline Polygon Fill

Solid filling of convex and concave polygon boundaries using edge tables and parity checks.

Edge Tables (ET & AET)

The Edge Table (ET) lists all polygon edges sorted by their minimum Y coordinate. The Active Edge Table (AET) contains only the edges intersecting the current scanline row, sorted by their active X coordinates.

Parity Rule

For each scanline row:

  1. Find all intersection points with edges in the AET.
  2. Sort intersections in increasing X order.
  3. Fill pixels between odd and even index intersection pairs (e.g. between 1st & 2nd, 3rd & 4th points).

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