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Optimally utilize tile hash key bits

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This commit is contained in:
Erik Broberg
2016-10-07 16:31:22 +02:00
parent dc410c213e
commit 0056c64b35
1 changed files with 12 additions and 8 deletions
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20
modules/globebrowsing/tile/tileindex.cpp
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@@ -97,18 +97,22 @@ namespace openspace {
/**
Creates a hash which can be used as key in hash maps
BITS | USAGE
0-6 | level
6-26 | x
26-46 | y
46-64 | reserved for future use, e.g. time key
Creates a hash which can be used as key in hash maps.
+-------+------------+-------+------------+
| USAGE | BIT RANGE | #BITS | MAX VALUE |
+-------+------------+-------+------------+
| level | 0 - 5 | 5 | 31 |
| x | 6 - 34 | 30 | 1073741824 |
| y | 35 - 63 | 29 | 536870912 |
+-------+------------+-------+------------+
*/
TileHashKey TileIndex::hashKey() const {
TileHashKey key = 0LL;
key |= level;
key |= x << 6;
key |= ((TileHashKey)y) << 26;
key |= x << 5;
key |= ((TileHashKey)y) << 35;
return key;
}