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Diffstat (limited to 'maketiles/README')
| -rw-r--r-- | maketiles/README | 28 |
1 files changed, 0 insertions, 28 deletions
diff --git a/maketiles/README b/maketiles/README deleted file mode 100644 index 64c6bb380..000000000 --- a/maketiles/README +++ /dev/null @@ -1,28 +0,0 @@ -File formats and structures - -Tiles are generated as PNG files. At the moment these are full-colour PNGs but -in due course we will probably want to use dithered images with a limited -palette. Generated tiles are named for their own SHA1 checksums, so that we -can eliminate duplicate tiles. The first-stage output of these scripts, -therefore, consists of a set of PNG files named by SHA1 and a text index which -maps tile locations to SHA1s. These are arranged as: - - toplevel/index text index of tiles - toplevel/tiles/0/0/0 location for images with SHA1s beginning - 000 - toplevel/tiles/0/0/0/00000000000000000000.png - first possible image file - -This format is not really acceptable for final deployment because many of the -image files won't be much larger than a filesystem block, so a large amount of -disk space would be wasted in storing them. Nor is the text index from tile -location to SHA1 acceptable. So a second program packs the image files into -catenated files with an index from SHA1 to offset and length in each file. -Separately, the index from tile location to SHA1 is turned into another index. -Both indices use Bernstein-style CDB files. - - toplevel/index.cdb binary index from tile location to SHA1 - toplevel/tiles/0/0/0/packed catenated file of images with SHA1s - beginning 000 - toplevel/tiles/0/0/0/index.cdb index of images in packed - |