# Lab 3: Stencil-Based Grid Subdivision

Author: Zhe Yuan

## How to Build

### Windows

Use Visual Studio (Developer Command Prompt) to compile the code.

```bat
.\make.bat
```

> **Note:** `cl` is only available in the Developer Command Prompt, change the path of `VsDevCmd.bat` in `make.bat` first.

### Linux / macOS — GCC via Makefile

```
make
```

This compiles all targets including `subdivide_grid`.

## How to Run

### Windows

```bat
subdivide_grid.exe {num_iter} {input_file}
```

### Linux / macOS

```bash
./subdivide_grid {num_iter} {input_file}
```

- `{num_iter}`: integer number of subdivision iterations (>= 0)
- `{input_file}`: a `.grid2D` file

The output file is written to the same directory as the input, with the suffix
`-subdiv.grid2D` appended (replacing the `.grid2D` extension).

### Optional `-off` flag

```bash
./subdivide_grid -off {num_iter} {input_file}
```

With `-off`, the program additionally writes a Geomview `.off` file named
`{basename}-subdiv.off`.

### Examples

```bash
./subdivide_grid 1 "Lab3 simple grids/grid2D-2x3-A.grid2D"
./subdivide_grid 3 "Lab3 grids/wave-A.grid2D"
./subdivide_grid -off 3 "Lab3 grids/sphere-A.grid2D"
```

## Visualization

Convert a `.grid2D` file to Geomview `.off` format:

```bash
./grid2off {input.grid2D}
```

## AI Tools Used

**GitHub Copilot** (via VS Code) was used for:

- Auto generating `Makefile` and this `README.md`.
- Auto completing during writing code.