public DReal Height(DVector3 position)
{
var ix = (int)position.x;
var iz = (int)position.z;
// Corner heights.
var ha = RawHeight(ix, iz);
var hb = RawHeight(ix + 1, iz);
var hc = RawHeight(ix, iz + 1);
var hd = RawHeight(ix + 1, iz + 1);
// Interpolation offsets.
var tx = position.x - ix;
var tz = position.z - iz;
return(DReal.BilinearLerp(ha, hb, hc, hd, tx, tz));
}