hexagon_grid_state()

static HexagonGridState* hexagon_grid_state ( double  size, const GBOX *  gbox, int32_t  srid  )

static

Definition at line 108 of file lwgeom_generate_grid.c.

{
        HexagonGridState *state = palloc0(sizeof(HexagonGridState));
        double col_width = 1.5 * size;
        double row_height = size * 2 * H;
 
        /* fill in state */
        state->cell_shape = SHAPE_HEXAGON;
        state->size = size;
        state->srid = srid;
        state->done = false;
        state->bounds = *gbox;
 
        /* Column address is just width / column width, with an */
        /* adjustment to account for partial overlaps */
        state->column_min = floor(gbox->xmin / col_width);
        if(gbox->xmin - state->column_min * col_width > size)
                state->column_min++;
 
        state->column_max = ceil(gbox->xmax / col_width);
        if(state->column_max * col_width - gbox->xmax > size)
                state->column_max--;
 
        /* Row address range depends on the odd/even column we're on */
        state->row_min_even = floor(gbox->ymin/row_height + 0.5);
        state->row_max_even = floor(gbox->ymax/row_height + 0.5);
        state->row_min_odd  = floor(gbox->ymin/row_height);
        state->row_max_odd  = floor(gbox->ymax/row_height);
 
        /* Set initial state */
        state->i = state->column_min;
        state->j = (state->i % 2) ? state->row_min_odd : state->row_min_even;
 
        return state;
}

References HexagonGridState::bounds, HexagonGridState::cell_shape, HexagonGridState::column_max, HexagonGridState::column_min, HexagonGridState::done, H, HexagonGridState::i, HexagonGridState::j, HexagonGridState::row_max_even, HexagonGridState::row_max_odd, HexagonGridState::row_min_even, HexagonGridState::row_min_odd, SHAPE_HEXAGON, HexagonGridState::size, HexagonGridState::srid, GBOX::xmax, GBOX::xmin, GBOX::ymax, and GBOX::ymin.

Referenced by ST_ShapeGrid().

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