added linear interpolation in image to use it at the terrain generation
[demo] / data / cubemap /
drwxr-xr-x   ..
-rw-r--r-- 11237370 cubemap_nx.hdr
-rw-r--r-- 14880503 cubemap_ny.hdr
-rw-r--r-- 11451458 cubemap_nz.hdr
-rw-r--r-- 12483034 cubemap_px.hdr
-rw-r--r-- 8006843 cubemap_py.hdr
-rw-r--r-- 12369084 cubemap_pz.hdr