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author | Craig Robbins <kde.psych@gmail.com> | 2015-02-23 16:25:14 +1000 |
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committer | Craig Robbins <kde.psych@gmail.com> | 2015-02-23 22:50:32 +1000 |
commit | 3b6480c5b0c968ad9f5a7cfb7ca494989be03629 (patch) | |
tree | 1d8acc30b33c652a2d7897ed5f89b3825888bd43 /src/util | |
parent | 51057a56f540f4e74b424e22c94357e5cb5268b2 (diff) | |
download | minetest-3b6480c5b0c968ad9f5a7cfb7ca494989be03629.tar.gz minetest-3b6480c5b0c968ad9f5a7cfb7ca494989be03629.tar.bz2 minetest-3b6480c5b0c968ad9f5a7cfb7ca494989be03629.zip |
Fix wrapDegrees family of functions
wrapDegrees() (renamed to modulo360f)
wrapDegrees_0_360
wrapDegrees_180
Minor errors were present in previous versions; see issue #2328
Diffstat (limited to 'src/util')
-rw-r--r-- | src/util/numeric.h | 83 |
1 files changed, 41 insertions, 42 deletions
diff --git a/src/util/numeric.h b/src/util/numeric.h index 7fc3d2167..42d9a87a9 100644 --- a/src/util/numeric.h +++ b/src/util/numeric.h @@ -184,57 +184,56 @@ inline void sortBoxVerticies(v3s16 &p1, v3s16 &p2) { } -/* - See test.cpp for example cases. - wraps degrees to the range of -360...360 - NOTE: Wrapping to 0...360 is not used because pitch needs negative values. -*/ -inline float wrapDegrees(float f) +/** Returns \p f wrapped to the range [-360, 360] + * + * See test.cpp for example cases. + * + * \note This is also used in cases where degrees wrapped to the range [0, 360] + * is innapropriate (e.g. pitch needs negative values) + * + * \internal functionally equivalent -- although precision may vary slightly -- + * to fmodf((f), 360.0f) however empirical tests indicate that this approach is + * faster. + */ +inline float modulo360f(float f) { - // Take examples of f=10, f=720.5, f=-0.5, f=-360.5 - // This results in - // 10, 720, -1, -361 - int i = floor(f); - // 0, 2, 0, -1 - int l = i / 360; - // NOTE: This would be used for wrapping to 0...360 - // 0, 2, -1, -2 - /*if(i < 0) - l -= 1;*/ - // 0, 720, 0, -360 - int k = l * 360; - // 10, 0.5, -0.5, -0.5 - f -= float(k); - return f; + int sign; + int whole; + float fraction; + + if (f < 0) { + f = -f; + sign = -1; + } else { + sign = 1; + } + + whole = f; + + fraction = f - whole; + whole %= 360; + + return sign * (whole + fraction); } -/* Wrap to 0...360 */ + +/** Returns \p f wrapped to the range [0, 360] + */ inline float wrapDegrees_0_360(float f) { - // Take examples of f=10, f=720.5, f=-0.5, f=-360.5 - // This results in - // 10, 720, -1, -361 - int i = floor(f); - // 0, 2, 0, -1 - int l = i / 360; - // Wrap to 0...360 - // 0, 2, -1, -2 - if(i < 0) - l -= 1; - // 0, 720, 0, -360 - int k = l * 360; - // 10, 0.5, -0.5, -0.5 - f -= float(k); - return f; + float value = modulo360f(f); + return value < 0 ? value + 360 : value; } -/* Wrap to -180...180 */ + +/** Returns \p f wrapped to the range [-180, 180] + */ inline float wrapDegrees_180(float f) { - f += 180; - f = wrapDegrees_0_360(f); - f -= 180; - return f; + float value = modulo360f(f + 180); + if (value < 0) + value += 360; + return value - 180; } /* |