Open-Harbor/osrm-backend
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Fix fromTop and fromLeft calculation

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This commit is contained in:
Patrick Niklaus 2016-06-21 16:50:06 +02:00
parent f6746d88b7
commit 93b6438cea
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GPG Key ID: E426891B5F978B1B
1 changed files with 5 additions and 3 deletions
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8
src/extractor/raster_source.cpp
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@ -54,7 +54,9 @@ RasterDatum RasterSource::GetRasterInterpolate(const int lon, const int lat) con
} }
const auto xthP = (lon - xmin) / xstep; const auto xthP = (lon - xmin) / xstep;
const auto ythP = (ymax - lat) / ystep; const auto ythP =
(ymax - lat) /
ystep; // the raster texture uses a different coordinate system with y pointing downwards
const std::size_t top = static_cast<std::size_t>(fmax(floor(ythP), 0)); const std::size_t top = static_cast<std::size_t>(fmax(floor(ythP), 0));
const std::size_t bottom = static_cast<std::size_t>(fmin(ceil(ythP), height - 1)); const std::size_t bottom = static_cast<std::size_t>(fmin(ceil(ythP), height - 1));
@ -62,8 +64,8 @@ RasterDatum RasterSource::GetRasterInterpolate(const int lon, const int lat) con
const std::size_t right = static_cast<std::size_t>(fmin(ceil(xthP), width - 1)); const std::size_t right = static_cast<std::size_t>(fmin(ceil(xthP), width - 1));
// Calculate distances from corners for bilinear interpolation // Calculate distances from corners for bilinear interpolation
const float fromLeft = (lon - left * xstep + xmin) / xstep; const float fromLeft = xthP - left; // this is the fraction part of xthP
const float fromTop = (ymax - top * ystep - lat) / ystep; const float fromTop = ythP - top; // this is the fraction part of ythP
const float fromRight = 1 - fromLeft; const float fromRight = 1 - fromLeft;
const float fromBottom = 1 - fromTop; const float fromBottom = 1 - fromTop;