37 if (!(prec >= 0 && prec <= maxprec_))
41 if (isnan(x) || isnan(y)) {
45 char grid[2 + 2 * maxprec_];
47 xh = int(floor(x / tile_)),
48 yh = int(floor(y / tile_));
55 grid[z++] = letters_[(tilegrid_ - (yh / tilegrid_) - 1)
56 * tilegrid_ + (xh / tilegrid_)];
57 grid[z++] = letters_[(tilegrid_ - (yh % tilegrid_) - 1)
58 * tilegrid_ + (xh % tilegrid_)];
60 real mult = real(pow(real(base_), max(tilelevel_ - prec, 0)));
62 ix = int(floor(xf / mult)),
63 iy = int(floor(yf / mult));
64 for (
int c = min(prec,
int(tilelevel_)); c--;) {
65 grid[z + c] = digits_[ ix % base_ ];
67 grid[z + c + prec] = digits_[ iy % base_ ];
70 if (prec > tilelevel_) {
71 xf -= floor(xf / mult);
72 yf -= floor(yf / mult);
73 mult = real(pow(real(base_), prec - tilelevel_));
74 ix = int(floor(xf * mult));
75 iy = int(floor(yf * mult));
76 for (
int c = prec - tilelevel_; c--;) {
77 grid[z + c + tilelevel_] = digits_[ ix % base_ ];
79 grid[z + c + tilelevel_ + prec] = digits_[ iy % base_ ];
83 int mlen = z + 2 * prec;
85 copy(grid, grid + mlen, gridref.begin());