Tile index shifting

[Jule-]

Following #6 issue, I am trying to generate and use terrain in Cesium.

When I try to generate terrain for N24E032.hgt SRTM 3 file:

ctb-tile --output-dir test N24E032.hgt
0...10...20...30...40...50...60...70...80...90...100 - done.

I can find in generated directory tree th

e terrain tile test\0\2\1.terrain which must be test\0\1\0.terrain accordingly to heightmap-1.0 terrain format.

After some investigation it seems that there is a mistake in Grid.hpp file:

inline TilePoint
  pixelsToTile(const PixelPoint &pixel) const {
    i_tile tx = (i_tile) ceil(pixel.x / mTileSize),
      ty = (i_tile) ceil(pixel.y / mTileSize);

    return TilePoint(tx, ty);
  }

should be:

inline TilePoint
  pixelsToTile(const PixelPoint &pixel) const {
    i_tile tx = (i_tile) pixel.x / mTileSize,
      ty = (i_tile) pixel.y / mTileSize;

    return TilePoint(tx, ty);
  }

It seems to solve my issue.

[Jule-]

Thank you!
I think I can explain this issue. On linux the method prototype ceil(int) must exist and logically it has to compile to no op while on Windows it doesn't exist so I have to force cast in float so I no longer have integer division but float division.
Well mystery solved!

[homme]

Ah yes, that would explain it, thanks!