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| author | btzy <bernard.14916@gmail.com> | 2019-01-12 16:28:43 +0800 |
|---|---|---|
| committer | Charles Pigott <charlespigott@googlemail.com> | 2019-01-20 19:43:56 +0000 |
| commit | 9d75600ac0137907d5c5ec4f0ff475e2efa2f596 (patch) | |
| tree | 049f914029ac9a58510a37bfd1a50e8b587056f2 | |
| parent | 5ad73e402908fb80a7d6b99f8f4146ac204764dd (diff) | |
| download | openttd-9d75600ac0137907d5c5ec4f0ff475e2efa2f596.tar.xz | |
Fix: Round up deltas for smooth scrolling, so target will be reached
| -rw-r--r-- | src/core/math_func.hpp | 17 | ||||
| -rw-r--r-- | src/viewport.cpp | 4 |
2 files changed, 19 insertions, 2 deletions
diff --git a/src/core/math_func.hpp b/src/core/math_func.hpp index df9142462..4a19033f4 100644 --- a/src/core/math_func.hpp +++ b/src/core/math_func.hpp @@ -346,6 +346,23 @@ static inline int RoundDivSU(int a, uint b) } } +/** + * Computes (a / b) rounded away from zero. + * @param a Numerator + * @param b Denominator + * @return Quotient, rounded away from zero + */ +static inline int DivAwayFromZero(int a, uint b) +{ + const int _b = static_cast<int>(b); + if (a > 0) { + return (a + _b - 1) / _b; + } else { + /* Note: Behaviour of negative numerator division is truncation toward zero. */ + return (a - _b + 1) / _b; + } +} + uint32 IntSqrt(uint32 num); #endif /* MATH_FUNC_HPP */ diff --git a/src/viewport.cpp b/src/viewport.cpp index da4ed2660..5e72aaa23 100644 --- a/src/viewport.cpp +++ b/src/viewport.cpp @@ -1813,8 +1813,8 @@ void UpdateViewportPosition(Window *w) if (_settings_client.gui.smooth_scroll) { int max_scroll = ScaleByMapSize1D(512 * ZOOM_LVL_BASE); /* Not at our desired position yet... */ - w->viewport->scrollpos_x += Clamp(delta_x / 4, -max_scroll, max_scroll); - w->viewport->scrollpos_y += Clamp(delta_y / 4, -max_scroll, max_scroll); + w->viewport->scrollpos_x += Clamp(DivAwayFromZero(delta_x, 4), -max_scroll, max_scroll); + w->viewport->scrollpos_y += Clamp(DivAwayFromZero(delta_y, 4), -max_scroll, max_scroll); } else { w->viewport->scrollpos_x = w->viewport->dest_scrollpos_x; w->viewport->scrollpos_y = w->viewport->dest_scrollpos_y; |