[Goblin]

From IL2 Setup at M4T : "..."Polygon Stipple" is a way of emulating or faking translucent shadows when the stencil buffer is turned off. It does this by creating a "dotted" effect that looks translucent (not unlike the stubble of incoming facial hair). Turn this off for a small performance boost. If stencil buffer and polygon stipple are both turned off, you'll get completely black shadows which isn't much of a drawback...".