From 70b6e0b716b658b9ae6fe1a86ae5dd5d8c9a0f25 Mon Sep 17 00:00:00 2001
From: ppatt <ppatt@users.noreply.github.com>
Date: Mon, 1 Dec 2025 12:52:22 +0200
Subject: [PATCH] Add Emscripten sysroot include paths to enable C library
 compilation for .emscripten build target

---
 README.md | 33 +++++++++++++++++++++++++++++++++
 build.zig | 14 ++++++++++++++
 2 files changed, 47 insertions(+)

diff --git a/README.md b/README.md
index 2d6feeb..1121831 100644
--- a/README.md
+++ b/README.md
@@ -27,6 +27,39 @@ pub fn build(b: *std.Build) void {
 }
 ```
 
+Zemscripten `build.zig` example:
+```zig
+pub fn build(b: *std.Build) void {
+    const target = b.resolveTargetQuery(.{
+        .cpu_arch = .wasm32,
+        .os_tag = .emscripten,
+    });
+
+    const wasm = b.addLibrary(.{ .name = "zemscripten-build", .linkage = .static, .root_module = b.createModule(.{
+        .root_source_file = b.path("main.zig"),
+        .target = target,
+        .optimize = optimize,
+    }) });
+
+    // Add Emscripten include paths for @cImport
+    const emsdk_path = b.dependency("emsdk", .{}).path("").getPath(b);
+    const emscripten_include_path = b.pathJoin(&.{ emsdk_path, "upstream", "emscripten", "cache", "sysroot", "include" });
+    wasm.root_module.addSystemIncludePath(.{ .cwd_relative = emscripten_include_path });
+
+    const zemscripten = b.dependency("zemscripten", .{});
+    const zmesh = b.dependency("zmesh", .{
+        .target = target,
+        .optimize = optimize,
+        .emscripten_include_path = emscripten_include_path,
+    });
+
+    wasm.root_module.addImport("zmesh", zmesh.module("root"));
+    wasm.linkLibrary(zmesh.artifact("zmesh"));
+
+    ...
+}
+```
+
 Now in your code you may import and use `zmesh`:
 
 ```zig
diff --git a/build.zig b/build.zig
index 5768607..3fc731e 100644
--- a/build.zig
+++ b/build.zig
@@ -15,6 +15,11 @@ pub fn build(b: *std.Build) void {
             "shared",
             "Build as shared library",
         ) orelse false,
+        .emscripten_include_path = b.option(
+            []const u8,
+            "emscripten_include_path",
+            "Path to emscripten include directory for Emscripten builds",
+        ),
     };
 
     const options_step = b.addOptions();
@@ -54,6 +59,15 @@ pub fn build(b: *std.Build) void {
     if (target.result.abi != .msvc)
         zmesh_lib.linkLibCpp();
 
+    // Add Emscripten sysroot include paths when building for emscripten target
+    if (target.result.os.tag == .emscripten) {
+        if (options.emscripten_include_path) |emscripten_include_path| {
+            zmesh_lib.addSystemIncludePath(.{ .cwd_relative = emscripten_include_path });
+        } else {
+            std.debug.panic("emscripten_include_path option must be provided when building for emscripten target\n", .{});
+        }
+    }
+
     const par_shapes_t = if (options.shape_use_32bit_indices)
         "-DPAR_SHAPES_T=uint32_t"
     else