Command Line Subcommands in OpenSCAD

Here’s the translation of the Go code to OpenSCAD, with explanations in Markdown format suitable for Hugo:

Our first program will demonstrate how to create a simple 3D object and use command-line arguments in OpenSCAD. Here’s the full source code:

// Define a module for our basic shape
module basic_shape(size) {
    cube(size);
}

// Main part of the script
function main() = 
    let(
        // Parse command line arguments
        args = $args,
        // Default size if no argument is provided
        default_size = 10,
        // Get the size from arguments or use default
        size = len(args) > 0 ? str(args[0]) : default_size
    )
    // Create and render the shape
    basic_shape(size);

// Call the main function
main();

In OpenSCAD, we don’t have the concept of subcommands like in the original Go example. Instead, we’ll focus on using command-line arguments to parameterize our script.

To run the script, save it as basic_shape.scad and use the OpenSCAD command-line interface:

$ openscad -o output.stl basic_shape.scad

This will create a default cube with size 10.

To specify a custom size:

$ openscad -o output.stl -D '$args=["20"]' basic_shape.scad

This will create a cube with size 20.

OpenSCAD doesn’t have built-in argument parsing like the flag package in the original example. Instead, we use the special $args variable to access command-line arguments.

In our script:

1. We define a basic_shape module that creates a cube of given size.
2. The main function parses arguments and calls basic_shape.
3. We use let() to create local variables for argument parsing.
4. If an argument is provided, we use it as the size; otherwise, we use a default value.
5. Finally, we call the main function to execute our script.

This example demonstrates how to create a simple parameterized 3D model in OpenSCAD and how to use command-line arguments to modify the output. While it doesn’t have the same level of command-line argument handling as the original Go example, it shows how to achieve similar functionality within the constraints of the OpenSCAD language.