pub fn preprocess(&self, src: &str) -> String {
        let reg = r#"\#include\("(.+.wgsl)"\);"#;
        let re = Regex::new(reg).unwrap();

        let processed = re.replace_all(src, |caps: &Captures| {
            let filename = caps[1].to_owned();
            let file_path = self.root.join(filename);

            let contents = fs::read_to_string(file_path).unwrap();
            contents
        });
        processed.to_string()
    }