One byte per pixel, row-major: 0 = transparent (air), non-zero =
solid. Distinct from AlphaSource (RGBA-shaped, 4 bytes per
pixel) — the mask is what PixelPerfectSprite keeps in memory
once the source has been thresholded, so per-pixel checks read one
byte instead of indexing into the alpha channel of an RGBA buffer.
One byte per pixel, row-major:
0= transparent (air), non-zero = solid. Distinct from AlphaSource (RGBA-shaped, 4 bytes per pixel) — the mask is what PixelPerfectSprite keeps in memory once the source has been thresholded, so per-pixel checks read one byte instead of indexing into the alpha channel of an RGBA buffer.