emscripten PoC

build.zig

@@ -43,6 +43,26 @@ pub fn build(b: *std.Build) void {
     }
     ensureGitLfsContent("/libs/zgpu/libs/dawn/x86_64-windows-gnu/dawn.lib") catch return;
 
+    // hacky emscripten override, just for PoC, do not ship!
+    const target = (std.zig.system.NativeTargetInfo.detect(options.target) catch unreachable).target;
+    if (target.os.tag == .emscripten) {
+        zsdl_pkg = zsdl.Package.build(b, .{});
+        zopengl_pkg = zopengl.Package.build(b, .{});
+
+        { // minimal sdl
+            // Workaround zig std lib not compiling for emscripten: see https://github.com/ziglang/zig/issues/10836
+            var options_override = options;
+            options_override.target.os_tag = .freestanding;
+
+            const exe = minimal_sdl.build(b, options_override);
+            exe.addModule("zsdl", zsdl_pkg.zsdl);
+            exe.addModule("zopengl", zopengl_pkg.zopengl);
+            zsdl_pkg.link(exe, target);
+            installDemoEmsc(b, exe, "minimal_sdl");
+        }
+        return;
+    }
+
     //
     // Packages
     //
@@ -159,7 +179,7 @@ fn samplesCrossPlatform(b: *std.Build, options: Options) void {
         const exe = minimal_sdl.build(b, options);
         exe.addModule("zsdl", zsdl_pkg.zsdl);
         exe.addModule("zopengl", zopengl_pkg.zopengl);
-        zsdl_pkg.link(exe);
+        zsdl_pkg.link(exe, null);
         installDemo(b, exe, "minimal_sdl");
     }
     { // triangle wgpu
@@ -644,6 +664,52 @@ fn installDemo(b: *std.Build, exe: *std.Build.CompileStep, comptime name: []cons
     b.getInstallStep().dependOn(install);
 }
 
+fn installDemoEmsc(b: *std.Build, exe: *std.Build.CompileStep, comptime name: []const u8) void {
+    comptime var desc_name: [256]u8 = [_]u8{0} ** 256;
+    comptime _ = std.mem.replace(u8, name, "_", " ", desc_name[0..]);
+    comptime var desc_size = std.mem.indexOf(u8, &desc_name, "\x00").?;
+
+    const install = b.step(name, "Build '" ++ desc_name[0..desc_size] ++ "' demo");
+    install.dependOn(&b.addInstallArtifact(exe).step);
+
+    { // "borrowed" & modifed version of https://github.com/floooh/pacman.zig/blob/main/build.zig
+        const emcc_path = std.fs.path.join(b.allocator, &.{ b.sysroot.?, "../../emcc" }) catch unreachable;
+        defer b.allocator.free(emcc_path);
+        const emrun_path = std.fs.path.join(b.allocator, &.{ b.sysroot.?, "../../emrun" }) catch unreachable;
+        defer b.allocator.free(emrun_path);
+
+        std.fs.cwd().makePath("zig-out/web") catch unreachable;
+        const emcc = b.addSystemCommand(&.{
+            emcc_path,
+            "-Os",
+            "--closure",
+            "1",
+            "emscripten/entry.c",
+            "-ozig-out/web/test.html",
+            "--shell-file",
+            "emscripten/shell.html",
+            "-Lzig-out/lib/",
+            "-l" ++ name,
+            "-sNO_FILESYSTEM=1",
+            "-sMALLOC='emmalloc'",
+            "-sASSERTIONS=0",
+            "-sEXPORTED_FUNCTIONS=['_main']",
+            "-sUSE_SDL=2",
+        });
+        emcc.step.dependOn(&exe.install_step.?.step);
+
+        // get the emcc step to run on 'zig build'
+        b.getInstallStep().dependOn(&emcc.step);
+
+        // a seperate run step using emrun
+        const emrun = b.addSystemCommand(&.{ emrun_path, "zig-out/web/test.html" });
+        emrun.step.dependOn(&emcc.step);
+        b.step(name ++ "-run", "Run '" ++ desc_name[0..desc_size] ++ "' demo (emscripten)").dependOn(&emrun.step);
+    }
+
+    b.getInstallStep().dependOn(install);
+}
+
 fn ensureZigVersion() !void {
     var installed_ver = @import("builtin").zig_version;
     installed_ver.build = null;
@@ -682,13 +748,14 @@ fn ensureTarget(cross: std.zig.CrossTarget) !void {
             if (target.os.version_range.semver.min.order(min_available) == .lt) break :blk false;
             break :blk true;
         },
+        .emscripten => target.cpu.arch.isWasm(),
         else => false,
     };
     if (!supported) {
         std.log.err("\n" ++
             \\---------------------------------------------------------------------------
             \\
-            \\Unsupported build target. Dawn/WebGPU binary for this target is not available.
+            \\Unsupported build target.
             \\
             \\Following targets are supported:
             \\
@@ -697,6 +764,7 @@ fn ensureTarget(cross: std.zig.CrossTarget) !void {
             \\x86_64-macos.12-none
             \\aarch64-linux-gnu
             \\aarch64-macos.12-none
+            \\wasm32-emscripten
             \\
             \\---------------------------------------------------------------------------
             \\

emscripten/emsdk/LICENSE

@@ -0,0 +1,27 @@
+Copyright (c) 2018 Emscripten authors (see AUTHORS in Emscripten)
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+
+----------------------------------------------------------------------------
+
+This is the MIT/Expat Licence. For more information see:
+
+1. http://www.opensource.org/licenses/mit-license.php
+
+2. http://en.wikipedia.org/wiki/MIT_License

emscripten/emsdk/README.md

@@ -0,0 +1,258 @@
+Emscripten SDK
+==============
+
+[![CircleCI](https://circleci.com/gh/emscripten-core/emsdk/tree/main.svg?style=svg)](https://circleci.com/gh/emscripten-core/emsdk/tree/main)
+
+The Emscripten toolchain is distributed as a standalone Emscripten SDK. The SDK
+provides all the required tools, such as Clang, Python and Node.js along with an
+update mechanism that enables migrating to newer Emscripten versions as they are
+released.
+
+You can also set up Emscripten from source, without the pre-built SDK, see
+"Installing from Source" below.
+
+## Downloads / How do I get the latest Emscripten build?
+
+To get started with Emscripten development, see the [Emscripten website
+documentation](https://emscripten.org/docs/getting_started/downloads.html).
+
+That explains how to use the emsdk to get the latest binary builds (without
+compiling from source). Basically, that amounts to
+
+```
+./emsdk install latest
+./emsdk activate latest
+```
+
+## SDK Concepts
+
+The Emscripten SDK is effectively a small package manager for tools that are
+used in conjunction with Emscripten. The following glossary highlights the
+important concepts to help understanding the internals of the SDK:
+
+* **Tool**: The basic unit of software bundled in the SDK. A Tool has a name and
+  a version. For example, 'clang-3.2-32bit' is a Tool that contains the 32-bit
+  version of the Clang v3.2 compiler.
+* **SDK**: A set of tools. For example, 'sdk-1.5.6-32bit' is an SDK consisting
+  of the tools `clang-3.2-32bit`, `node-0.10.17-32bit`, `python-2.7.5.1-32bit`
+  and `emscripten-1.5.6`.
+* **Active Tool/SDK**: Emscripten stores compiler configuration in a
+  user-specific file **~/.emscripten**. This file points to paths for
+  Emscripten, Python, Clang and so on. If the file ~/.emscripten is configured
+  to point to a Tool in a specific directory, then that tool is denoted as being
+  **active**. The Emscripten Command Prompt always gives access to the currently
+  active Tools. This mechanism allows switching between different installed SDK
+  versions easily.
+* **emsdk**: This is the name of the manager script that Emscripten SDK is
+  accessed through. Most operations are of the form `emsdk command`. To access
+  the emsdk script, launch the Emscripten Command Prompt.
+
+## System Requirements
+
+Using the emsdk pre-compiled packages requires only the minimal set of
+dependenencies lists below.  When building from source a wider set of tools
+include git, cmake, and a host compiler are required. See:
+https://emscripten.org/docs/building_from_source/toolchain_what_is_needed.html.
+
+### Mac OS X
+
+- For Intel-based Macs, macOS 10.13 or newer. For ARM64 M1 based Macs, macOS
+  11.0 or newer.
+- `java`: For running closure compiler (optional).  After installing emscripten
+  via emsdk, typing 'emcc --help' should pop up a OS X dialog "Java is not
+  installed. To open java, you need a Java SE 6 runtime. Would you like to
+  install one now?" that will automatically download a Java runtime to the
+  system.
+
+### Linux
+
+- `python`: Version 2.7.0 or above.
+- `java`: For running closure compiler (optional)
+
+The emsdk pre-compiled binaries are built aginst Ubuntu/Xenial 16.04 LTS and
+therefore depend on system libraries compatiable with versions of `glibc` and
+`libstdc++` present in that release.  If your linux distribution is very old
+you may not be able to use the pre-compiled binaries packages.
+
+### Windows
+
+- `java`: For running closure compiler (optional)
+
+## Uninstalling the Emscripten SDK
+
+To remove the Emscripten SDK, simply delete the emsdk directory.
+
+## SDK Maintenance
+
+The following tasks are common with the Emscripten SDK:
+
+### How do I work the emsdk utility?
+
+Run `emsdk help` or just `emsdk` to get information about all available commands.
+
+### How do I check the installation status and version of the SDK and tools?
+
+To get a list of all currently installed tools and SDK versions, and all
+available tools, run `emsdk list`.
+* A line will be printed for each tool/SDK that is available for installation.
+* The text `INSTALLED` will be shown for each tool that has already been
+  installed.
+* If a tool/SDK is currently active, a star * will be shown next to it.
+* If a tool/SDK is currently active, but the terminal your are calling emsdk
+  from does not have `PATH` and environment set up to utilize that tool, a star
+  in parentheses (\*) will be shown next to it. Run `emsdk_env.bat` (Windows) or
+  `source ./emsdk_env.sh` (Linux and OS X) to set up the environment for the
+  calling terminal.
+
+### How do I install a tool/SDK version?
+
+Run the command `emsdk install <tool/sdk name>` to download and install a new
+tool or an SDK version.
+
+### How do I remove a tool or an SDK?
+
+Run the command `emsdk uninstall <tool/sdk name>` to delete the given tool or
+SDK from the local hard drive completely.
+
+### How do I check for updates to the Emscripten SDK?
+
+`emsdk update` will fetch package information for all the new tools and
+SDK versions. After that, run `emsdk install <tool/sdk name>` to install a new
+version.
+
+### How do I install an old Emscripten compiler version?
+
+Emsdk contains a history of old compiler versions that you can use to maintain
+your migration path. Type `emsdk list --old` to get a list of archived tool and
+SDK versions, and `emsdk install <name_of_tool>` to install it.
+
+### I want to build from source!
+
+Some Emsdk Tool and SDK targets refer to packages that are precompiled, and
+no compilation is needed when installing them. Other Emsdk Tools and SDK
+targets come "from source", meaning that they will fetch the source repositories
+using git, and compile the package on demand.
+
+When you run `emsdk list`, it will group the Tools and SDKs under these two
+categories.
+
+To obtain and build latest wasm SDK from source, run
+
+```
+emsdk install sdk-main-64bit
+emsdk activate sdk-main-64bit
+```
+
+You can use this target for example to bootstrap developing patches to LLVM,
+Binaryen or Emscripten. (After initial installation, use `git remote add`
+in the cloned tree to add your own fork to push changes as patches)
+
+If you only intend to contribute to Emscripten repository, and not to LLVM
+or Binaryen, you can also use precompiled versions of them, and only git
+clone the Emscripten repository. For more details, see
+
+https://emscripten.org/docs/contributing/developers_guide.html?highlight=developer#setting-up
+
+### When working on git branches compiled from source, how do I update to a newer compiler version?
+
+Unlike tags and precompiled versions, a few of the SDK packages are based on
+"moving" git branches and compiled from source (e.g. sdk-main,
+sdk-main, emscripten-main, binaryen-main). Because of that, the
+compiled versions will eventually go out of date as new commits are introduced
+to the development branches. To update an old compiled installation of one of
+this branches, simply reissue the "emsdk install" command on that tool/SDK. This
+will `git pull` the latest changes to the branch and issue an incremental
+recompilation of the target in question. This way you can keep calling `emsdk
+install` to keep an Emscripten installation up to date with a given git branch.
+
+Note though that if the previously compiled branch is very old, sometimes CMake
+gets confused and is unable to properly rebuild a project. This has happened in
+the past e.g. when LLVM migrated to requiring a newer CMake version. In cases of
+any odd compilation errors, it is advised to try deleting the intermediate build
+directory to clear the build (e.g. "emsdk/clang/fastcomp/build_xxx/") before
+reissuing `emsdk install`.
+
+### How do I change the currently active SDK version?
+
+You can toggle between different tools and SDK versions by running `emsdk
+activate <tool/sdk name>`. Activating a tool will set up `~/.emscripten` to
+point to that particular tool. On Windows, you can pass the option `--permanent` to
+the `activate` command to register the environment permanently for the current user. Use `--system` to do this for all users.
+
+### How do I build multiple projects with different SDK versions in parallel?
+
+By default, Emscripten locates all configuration files in the home directory of
+the user. This may be a problem if you need to simultaneously build with
+multiple Emscripten compiler versions, since the user home directory can only be
+configured to point to one compiler at a time. This can be overcome by
+specifying the '--embedded' option as a parameter to 'emsdk activate', which
+will signal emsdk to generate the compiler configuration files inside the emsdk
+root directory instead of the user home directory. Use this option also when it
+is desirable to run emsdk in a fully portable mode that does not touch any files
+outside the emsdk directory.
+
+### How do I track the latest Emscripten development with the SDK?
+
+A common and supported use case of the Emscripten SDK is to enable the workflow
+where you directly interact with the github repositories. This allows you to
+obtain new features and latest fixes immediately as they are pushed to the
+github repository, without having to wait for release to be tagged. You do not
+need a github account or a fork of Emscripten to do this. To switch to using the
+latest git development branch `main`, run the following:
+
+    emsdk install git-1.9.4 # Install git. Skip if the system already has it.
+    emsdk install sdk-main-64bit # Clone+pull the latest emscripten-core/emscripten/main.
+    emsdk activate sdk-main-64bit # Set the main SDK as the currently active one.
+
+### How do I use my own Emscripten github fork with the SDK?
+
+It is also possible to use your own fork of the Emscripten repository via the
+SDK. This is achieved with standard git machinery, so there if you are already
+acquainted with working on multiple remotes in a git clone, these steps should
+be familiar to you. This is useful in the case when you want to make your own
+modifications to the Emscripten toolchain, but still keep using the SDK
+environment and tools. To set up your own fork as the currently active
+Emscripten toolchain, first install the `sdk-main` SDK like shown in the
+previous section, and then run the following commands in the emsdk directory:
+
+    cd emscripten/main
+    # Add a git remote link to your own repository.
+    git remote add myremote https://github.com/mygituseraccount/emscripten.git
+    # Obtain the changes in your link.
+    git fetch myremote
+    # Switch the emscripten-main tool to use your fork.
+    git checkout -b mymain --track myremote/main
+
+In this way you can utilize the Emscripten SDK tools while using your own git
+fork. You can switch back and forth between remotes via the `git checkout`
+command as usual.
+
+### How do I use Emscripten SDK with a custom version of python, java, node.js or some other tool?
+
+The provided Emscripten SDK targets are metapackages that refer to a specific
+set of tools that have been tested to work together. For example,
+`sdk-1.35.0-64bit` is an alias to the individual packages `clang-e1.35.0-64bit`,
+`node-4.1.1-64bit`, `python-2.7.5.3-64bit` and `emscripten-1.35.0`. This means
+that if you install this version of the SDK, both python and node.js will be
+installed inside emsdk as well. If you want to use your own/system python or
+node.js instead, you can opt to install emsdk by specifying the individual set
+of packages that you want to use. For example, `emsdk install
+clang-e1.35.0-64bit emscripten-1.35.0` will only install the Emscripten
+LLVM/Clang compiler and the Emscripten frontend without supplying python and
+node.js.
+
+### My installation fails with "fatal error: ld terminated with signal 9 [Killed]"?
+
+This may happen if the system runs out of memory. If you are attempting to build
+one of the packages from source and are running in a virtual OS or may have
+relatively little RAM and disk space available, then the build might fail. Try
+feeding your computer more memory. Another thing to try is to force emsdk
+install to build in a singlethreaded mode, which will require less RAM
+simultaneously. To do this, pass the `-j1` flag to the `emsdk install` command.
+
+### How do I run Emscripten on 32-bit systems or non-x86-64 systems?
+
+Emscripten SDK releases are no longer packaged or maintained for 32-bit systems.
+If you want to run Emscripten on a 32-bit system, you can try manually building
+the compiler. Follow the steps in the above section "Building an Emscripten tag
+or branch from source" to get started.