forked from MTSR/mapserver
47 lines
1.2 KiB
Go
47 lines
1.2 KiB
Go
package coords
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import "mapserver/types"
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// https://bitbucket.org/s_l_teichmann/mtsatellite/src/e1bf980a2b278c570b3f44f9452c9c087558acb3/common/coords.go?at=default&fileviewer=file-view-default
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const (
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numBitsPerComponent = 12
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modulo = 1 << numBitsPerComponent
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maxPositive = modulo / 2
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minValue = -1 << (numBitsPerComponent - 1)
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maxValue = 1<<(numBitsPerComponent-1) - 1
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MinPlainCoord = -34351347711
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)
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func CoordToPlain(c *types.MapBlockCoords) int64 {
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return int64(c.Z)<<(2*numBitsPerComponent) +
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int64(c.Y)<<numBitsPerComponent +
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int64(c.X)
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}
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func unsignedToSigned(i int16) int {
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if i < maxPositive {
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return int(i)
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}
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return int(i - maxPositive*2)
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}
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// To match C++ code.
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func pythonModulo(i int16) int16 {
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const mask = modulo - 1
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if i >= 0 {
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return i & mask
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}
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return modulo - -i&mask
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}
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func PlainToCoord(i int64) *types.MapBlockCoords {
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c := types.MapBlockCoords{}
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c.X = unsignedToSigned(pythonModulo(int16(i)))
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i = (i - int64(c.X)) >> numBitsPerComponent
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c.Y = unsignedToSigned(pythonModulo(int16(i)))
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i = (i - int64(c.Y)) >> numBitsPerComponent
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c.Z = unsignedToSigned(pythonModulo(int16(i)))
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return &c
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}
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