Viewing & Rendering

Polygon-Filling Algorithm

Find intersection of scan line with all edges of polygon by solving simultaneous equations.
Sort the intersection by increasing x-coordinates.
Fill in all pixels between pairs of intersections that lie interior to the polygon, using the odd-parity rule to determine if a point is inside a region. Each vertex encountered flips the parity bit. The rule is: draw when parity is odd, don't draw when parity is even. Parity always starts out even.
Special cases: vertices, horizontal lines, very thin slivers.

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