From ee84b309baaac9c3d1ab4f3fe9a7d95140d9c795 Mon Sep 17 00:00:00 2001
From: Julian Orth <ju.orth@gmail.com>
Date: Sat, 4 Oct 2025 22:32:59 +0200
Subject: [PATCH] build.rs: don't build compile-shaders if shaders are
 unchanged

---
 Cargo.lock                           |  1 +
 Cargo.toml                           |  2 ++
 build/vulkan.rs                      |  7 +++++-
 build/vulkan/hash.rs                 | 32 ++++++++++++++++++++++++++++
 compile-shaders/build-rs/src/main.rs |  9 +-------
 compile-shaders/core/src/lib.rs      | 32 +---------------------------
 6 files changed, 43 insertions(+), 40 deletions(-)
 create mode 100644 build/vulkan/hash.rs

diff --git a/Cargo.lock b/Cargo.lock
index 8db7819e..2dd4e5f9 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -637,6 +637,7 @@ dependencies = [
  "tiny-skia",
  "tracy-client-sys",
  "uapi",
+ "walkdir",
  "with_builtin_macros",
 ]
 
diff --git a/Cargo.toml b/Cargo.toml
index 05379806..3dbce079 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -74,6 +74,8 @@ repc = "0.1.1"
 anyhow = "1.0.79"
 bstr = { version = "1.9.0", default-features = false, features = ["std"] }
 cc = "1.0.86"
+blake3 = "1.8.2"
+walkdir = "2.5.0"
 
 #[profile.dev.build-override]
 #opt-level = 3
diff --git a/build/vulkan.rs b/build/vulkan.rs
index 9318d331..6a903a43 100644
--- a/build/vulkan.rs
+++ b/build/vulkan.rs
@@ -1,9 +1,14 @@
-use {anyhow::bail, std::process::Command};
+mod hash;
+
+use {crate::vulkan::hash::unchanged, anyhow::bail, std::process::Command};
 
 pub fn main() -> anyhow::Result<()> {
     if !std::fs::exists("compile-shaders")? {
         return Ok(());
     }
+    if unchanged() {
+        return Ok(());
+    }
     let code = Command::new("cargo")
         .args([
             "run",
diff --git a/build/vulkan/hash.rs b/build/vulkan/hash.rs
new file mode 100644
index 00000000..dabd45fc
--- /dev/null
+++ b/build/vulkan/hash.rs
@@ -0,0 +1,32 @@
+use {std::fmt::Write, walkdir::WalkDir};
+
+pub const ROOT: &str = "src/gfx_apis/vulkan/shaders";
+pub const HASH: &str = "src/gfx_apis/vulkan/shaders_hash.txt";
+
+fn calculate_hash() -> anyhow::Result<String> {
+    let dir = WalkDir::new(ROOT);
+    let mut files = vec![];
+    for file in dir {
+        let file = file?;
+        if file.file_type().is_file() {
+            files.push(file.path().to_path_buf());
+        }
+    }
+    files.sort();
+    let mut out = String::new();
+    for file in files {
+        let data = std::fs::read(&file)?;
+        writeln!(out, "{} {}", blake3::hash(&data).to_hex(), file.display())?;
+    }
+    Ok(out)
+}
+
+pub fn unchanged() -> bool {
+    let Ok(actual) = std::fs::read_to_string(HASH) else {
+        return false;
+    };
+    let Ok(expected) = calculate_hash() else {
+        return false;
+    };
+    actual == expected
+}
diff --git a/compile-shaders/build-rs/src/main.rs b/compile-shaders/build-rs/src/main.rs
index 13895519..8e62c22d 100644
--- a/compile-shaders/build-rs/src/main.rs
+++ b/compile-shaders/build-rs/src/main.rs
@@ -1,14 +1,7 @@
-use {
-    anyhow::bail,
-    compile_shaders_core::{ROOT, unchanged},
-    std::process::Command,
-};
+use {anyhow::bail, compile_shaders_core::ROOT, std::process::Command};
 
 fn main() -> anyhow::Result<()> {
     println!("cargo:rerun-if-changed={}", ROOT);
-    if unchanged() {
-        return Ok(());
-    }
     let code = Command::new("cargo")
         .args([
             "run",
diff --git a/compile-shaders/core/src/lib.rs b/compile-shaders/core/src/lib.rs
index b9a7b348..53647204 100644
--- a/compile-shaders/core/src/lib.rs
+++ b/compile-shaders/core/src/lib.rs
@@ -1,36 +1,6 @@
-use {std::fmt::Write, walkdir::WalkDir};
+include!("../../../build/vulkan/hash.rs");
 
-pub const ROOT: &str = "src/gfx_apis/vulkan/shaders";
 pub const BIN: &str = "src/gfx_apis/vulkan/shaders_bin";
-pub const HASH: &str = "src/gfx_apis/vulkan/shaders_hash.txt";
-
-fn calculate_hash() -> anyhow::Result<String> {
-    let dir = WalkDir::new(ROOT);
-    let mut files = vec![];
-    for file in dir {
-        let file = file?;
-        if file.file_type().is_file() {
-            files.push(file.path().to_path_buf());
-        }
-    }
-    files.sort();
-    let mut out = String::new();
-    for file in files {
-        let data = std::fs::read(&file)?;
-        writeln!(out, "{} {}", blake3::hash(&data).to_hex(), file.display())?;
-    }
-    Ok(out)
-}
-
-pub fn unchanged() -> bool {
-    let Ok(actual) = std::fs::read_to_string(HASH) else {
-        return false;
-    };
-    let Ok(expected) = calculate_hash() else {
-        return false;
-    };
-    actual == expected
-}
 
 pub fn update_hash() -> anyhow::Result<()> {
     std::fs::write(HASH, calculate_hash()?)?;