You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: point_gen.rs
    path of file: ./repos/wgpu-rs/examples/water
    
    the code of the file until where you have to start completion: //!
//! This module covers generating points in a hexagonal fashion.
//!

use bytemuck::{Pod, Zeroable};
use cgmath::{InnerSpace, Point3, Vector3};
use std::collections::HashMap;

// The following constants are used in calculations.
// A and B are multiplication factors for x and y.

///
///
    
    pub fn generate(radius: f32) -> Self {
        let width = q_given_r(radius);
        let half_width = (width / 2) as isize;
        let mut map = HashMap::new();

        for i in -half_width..=half_width {
            let x_o = i as f32;
            for j in -half_width..=half_width {
                let y_o = j as f32;
                let x = A * (x_o * C45 - y_o * S45);
                let z = B * (x_o * S45 + y_o * C45);
                if x.hypot(z) < radius {
                    let x = (x * 2.0).round() as i16;
                    let z = ((z / B) * std::f32::consts::SQRT_2).round() as i16;
                    map.insert((i, j), [x, z]);
                }
            }
        }
        Self {
            vertices: map,
            half_size: half_width,
        }
    }