TilePartial

A TilePartial is used to render at least a portion of a missing tile at the closest available level-of-detail. There are three cases of instantiation:

1. Closest available level-of-detail is an ancestor of a tile.

• The target tile is completely covered by a portion of the found tile.

• There is no positional offset nor scaling of the found tile, it will cover the target tile in its entirety.

• There is a UV offset to render the relevant portion of the found tile.

2. Closest available level-of-detail is a descendant tile.

• The target tile is partially covered by the found tile.

• There is a positional offset and scale of the found tile relative to the target tile.

• Thre is no UV offset, the found tile is rendered in its entirety.

3. Closest available level-of-detail is an ancestor of the target, but is used to cover a missing descedant. This occurs when one or more descendant tiles cover a portion of the target tile, but an ancestor is required to fill in a missing descendant.

• The target tile is partially covered by the found tile.

• There is a positional offset and scale of the found tile relative to the descendant the tile is covering.

• There is a UV offset to render the relevant portion of the found tile which covers descendant.