Shader code paths (#13908)

# Objective

Add extra metadata for the shader examples that contains the location of
their associated shader file(s). This is to be used for the bevy website
shader examples so that the shader code is underneath the rust code.

## Solution

Parse the example rust files for mentions of `.wgsl`, `.frag`, and
`.vert`, then append the found paths to a field called
`shader_code_paths` in the generated `index.md`s for each shader
example.

tools/example-showcase/Cargo.toml

@@ -13,6 +13,7 @@ toml_edit = { version = "0.22.7", default-features = false, features = [
   "parse",
 ] }
 pbr = "1.1"
+regex = "1.10.5"
 
 [lints]
 workspace = true

tools/example-showcase/src/main.rs

@@ -1,7 +1,7 @@
 //! Tool to run all examples or generate a showcase page for the Bevy website.
 
 use std::{
-    collections::{hash_map::DefaultHasher, HashMap},
+    collections::{hash_map::DefaultHasher, HashMap, HashSet},
     fmt::Display,
     fs::{self, File},
     hash::{Hash, Hasher},
@@ -14,6 +14,7 @@ use std::{
 
 use clap::{error::ErrorKind, CommandFactory, Parser, ValueEnum};
 use pbr::ProgressBar;
+use regex::Regex;
 use toml_edit::DocumentMut;
 use xshell::{cmd, Shell};
 
@@ -546,6 +547,7 @@ technical_name = \"{}\"
 link = \"/examples{}/{}/{}\"
 image = \"../static/screenshots/{}/{}.png\"
 code_path = \"content/examples{}/{}\"
+shader_code_paths = {:?}
 github_code_path = \"{}\"
 header_message = \"Examples ({})\"
 +++",
@@ -580,6 +582,7 @@ header_message = \"Examples ({})\"
                                 .skip(1)
                                 .collect::<PathBuf>()
                                 .display(),
+                            to_show.shader_paths,
                             &to_show.path,
                             match api {
                                 WebApi::Webgpu => "WebGPU",
@@ -723,6 +726,18 @@ fn parse_examples() -> Vec<Example> {
         .flat_map(|val| {
             let technical_name = val.get("name").unwrap().as_str().unwrap().to_string();
 
+            let source_code = fs::read_to_string(val["path"].as_str().unwrap()).unwrap();
+            let shader_regex =
+                Regex::new(r"(shaders\/\w+\.wgsl)|(shaders\/\w+\.frag)|(shaders\/\w+\.vert)")
+                    .unwrap();
+
+            // Find all instances of references to shader files, collect into set to avoid duplicates, then convert to vec of strings.
+            let shader_paths = Vec::from_iter(
+                shader_regex
+                    .find_iter(&source_code)
+                    .map(|matches| matches.as_str().to_owned())
+                    .collect::<HashSet<String>>(),
+            );
             if metadatas
                 .get(&technical_name)
                 .and_then(|metadata| metadata.get("hidden"))
@@ -736,6 +751,7 @@ fn parse_examples() -> Vec<Example> {
             metadatas.get(&technical_name).map(|metadata| Example {
                 technical_name,
                 path: val["path"].as_str().unwrap().to_string(),
+                shader_paths,
                 name: metadata["name"].as_str().unwrap().to_string(),
                 description: metadata["description"].as_str().unwrap().to_string(),
                 category: metadata["category"].as_str().unwrap().to_string(),
@@ -780,9 +796,10 @@ struct Example {
     technical_name: String,
     /// Path to the example file
     path: String,
+    /// Path to the associated wgsl file if it exists
+    shader_paths: Vec<String>,
     /// List of non default required features
     required_features: Vec<String>,
-
     // From the example metadata
     /// Pretty name, used for display
     name: String,