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: cube.rs
    path of file: ./repos/ggez/examples
    
    the code of the file until where you have to start completion: //! How to draw a 3D cube in ggez.
//!
//! ggez doesn't provide any 3D drawing itself, but it exposes
//! the underlying `gfx-rs` data types, so you can bypass ggez's
//! drawing code entirely and write your own.

use crevice::std140::AsStd140;
use ggez::event;
use ggez::glam::*;
use ggez::graphics;
use ggez::{Context, GameResult};
use std::env;
use std::f32;
use std::path;
use wgpu::util::DeviceExt;

type Isometry3 = Mat4;
type Point3 = Vec3;
type Vector3 = Vec3;

#[derive(Clone, Copy, bytemuck::Zeroable, bytemuck::Pod)]
#[repr(C)]
struct Vertex {
    pos: [f32; 4],
    tex_coord: [f32; 2],
}

impl Vertex {
    fn new(p: [i8; 3], t: [i8; 2]) -> Vertex {
        Vertex {
            pos: [f32::from(p[0]), f32::from(p[1]), f32::from(p[2]), 1.0],
            tex_coord: [f32::from(t[0]), f32::from(t[1])],
        }
    }
}

#[derive(AsStd140)]
struct Locals {
    transform: mint::ColumnMatrix4<f32>,
    rotation: mint::ColumnMatrix4<f32>,
}

fn default_view() -> Isometry3 {
    // Eye location, target location, up-vector
    Mat4::look_at_rh(
        Point3::new(1.5f32, -5.0, 3.0),
        Point3::new(0f32, 0.0, 0.0),
        Vector3::Z,
    )
}

struct MainState {
    frames: usize,
    transform: mint::ColumnMatrix4<f32>,
    rotation: f32,

    verts: wgpu::Buffer,
    inds: wgpu::Buffer,
    pipeline: wgpu::RenderPipeline,
    locals: wgpu::Buffer,
    bind_group: wgpu::BindGroup,
    depth: graphics::ScreenImage,
}

impl MainState {
    fn new(ctx: &mut Context) -> Self {
        // Shaders.
        let shader = ctx
            .gfx
            .wgpu()
            .device
            .create_shader_module(wgpu::include_wgsl!("../resources/cube.wgsl"));

        // Cube geometry
        let vertex_data = [
            // top (0, 0, 1)
            Vertex::new([-1, -1, 1], [0, 0]),
          
    
    fn draw(&mut self, ctx: &mut Context) -> GameResult {
        {
            let locals = Locals {
                transform: self.transform,
                rotation: Mat4::from_rotation_z(self.rotation).into(),
            };
            ctx.gfx
                .wgpu()
                .queue
                .write_buffer(&self.locals, 0, locals.as_std140().as_bytes());

            let depth = self.depth.image(ctx);

            let frame = ctx.gfx.frame().clone();
            let cmd = ctx.gfx.commands().unwrap();
            let mut pass = cmd.begin_render_pass(&wgpu::RenderPassDescriptor {
                label: None,
                color_attachments: &[Some(wgpu::RenderPassColorAttachment {
                    view: frame.wgpu().1,
                    resolve_target: None,
                    ops: wgpu::Operations {
                        load: wgpu::LoadOp::Clear(
                            graphics::LinearColor::from(graphics::Color::new(0.1, 0.1, 0.1, 1.0))
                                .into(),
                        ),
                        store: true,
                    },
                })],
                depth_stencil_attachment: Some(wgpu::RenderPassDepthStencilAttachment {
                    view: depth.wgpu().1,
                    depth_ops: Some(wgpu::Operations {
                        load: wgpu::LoadOp::Clear(0.),
                        store: false,
                    }),
                    stencil_ops: None,
                }),
            });

            pass.set_pipeline(&self.pipeline);
            pass.set_bind_group(0, &self.bind_group, &[]);
            pass.set_vertex_buffer(0, self.verts.slice(..));
            pass.set_index_buffer(self.inds.slice(..), wgpu::IndexFormat::Uint32);
            pass.draw_indexed(0..36, 0, 0..1);
        }

        let mut canvas = graphics::Canvas::from_frame(ctx, None);

        // Do ggez drawing
        let dest_point1 = Vec2::new(10.0, 210.0);
        let dest_point2 = Vec2::new(10.0, 250.0);
        canvas.draw(
            &graphics::Text::new("You can mix ggez and wgpu drawing;"),
            dest_point1,
        );
        canvas.draw(
            &graphics::Text::new("it basically draws wgpu stuff first, then ggez"),
            dest_point2,
        );

        canvas.finish(ctx)?;

        self.frames += 1;
        if (self.frames % 10) == 0 {
            println!("FPS: {}", ctx.time.fps());
        }

        Ok(())
    }