wgsl include preprocessor; refactor pbr

src/shaders/preprocessor.rs

@@ -0,0 +1,24 @@
+use wgpu;
+use regex::Regex;
+use std::fs::read_to_string;
+
+pub fn preprocess_wgsl(filename: &str) -> wgpu::ShaderSource {
+    let source_path = env!("CARGO_MANIFEST_DIR").to_owned() + "/src/shaders/wgsl/" + filename;
+    println!("preprocess_wgsl: loading source {}", source_path);
+    let mut source =
+        read_to_string(&source_path)
+            .unwrap();
+
+    let re = Regex::new(r"#include (.*?)\n").unwrap();
+    for cap in re.captures_iter(&source.clone()) {
+        let whole_match = &cap[0];
+        let mut full_path: String = source_path.to_owned();
+        full_path = full_path.replace(filename, &cap[1]);
+
+        println!("preprocess_wgsl: replacing {} with file {}", whole_match, full_path);
+        let nested_source = read_to_string(full_path).unwrap();
+        source = source.replace(whole_match, &nested_source);
+    }
+
+    return wgpu::ShaderSource::Wgsl(source.into());
+}