### External dependencies

The dyna3 program depends on some externally-maintained JavaScript
libraries/modules. The package uses npm to track these external dependencies.
A module externals.js is automatically generated from the package_lock.json file
created by npm to load the necessary modules at runtime.

The generation is performed by pkglock_to_externals.litcoffee, which also
records the main importable file within the library, as there does not seem
to be a systematic way to generate that filename from the module name.
```javascript

    importable = { three: 'build/three.module.js' }

```
Currently, dyna3 makes use of the following external libraries:
```javascript

    if process.argv.length < 3
        header =
        """
        /* External module loader for dyna3
         * Generated automatically from package-lock.json by
         * helpers/pkglock_to_externals.litcoffee
         */

        """
        process.stdout.write header
    fs = require 'fs'
    pl = fs.readFileSync 'package-lock.json'
    pdata = JSON.parse pl
    for dep in Object.keys pdata.dependencies
        if process.argv.length > 2
            process.stdout.write "* #{dep}\n"
        else
            block =
            """
            export var #{dep};
            export var #{dep}Loaded = new Promise(async function(resolve, reject) {
                var success = false;
                try {
                    #{dep} = await import('https://cdn.jsdelivr.net/npm/#{dep}@#{pdata.dependencies[dep].version}/#{importable[dep]}');
                    console.log('CDN import of #{dep} module OK');
                    success = true;
                } catch(err) {
                    try {
                        #{dep} = await import('./node_modules/#{dep}/#{importable[dep]}');
                        success = true;
                    } catch(err) {
                    }
                    console.log('Used local fallback for #{dep} module');
                }
                if (success) { resolve(); } else { reject(); }
            });

            """
            process.stdout.write block

```