1 files changed, 128 insertions, 0 deletions
diff --git a/build.zig b/build.zig
new file mode 100644
index 0000000..590d913
--- /dev/null
+++ b/build.zig
@@ -0,0 +1,128 @@
+const std = @import("std");
+const Build = std.Build;
+const OptimizeMode = std.builtin.OptimizeMode;
+const ResolvedTarget = Build.ResolvedTarget;
+const Dependency = Build.Dependency;
+const sokol = @import("sokol");
+const cimgui = @import("cimgui");
+
+pub fn build(b: *Build) !void {
+    const target = b.standardTargetOptions(.{});
+    const optimize = b.standardOptimizeOption(.{});
+
+    const opt_docking = b.option(bool, "docking", "Build with docking support") orelse false;
+
+    // Get the matching Zig module name, C header search path and C library for
+    // vanilla imgui vs the imgui docking branch.
+    const cimgui_conf = cimgui.getConfig(opt_docking);
+
+    // note that the sokol dependency is built with `.with_sokol_imgui = true`
+    const dep_sokol = b.dependency("sokol", .{
+        .target = target,
+        .optimize = optimize,
+        .with_sokol_imgui = true,
+    });
+    const dep_cimgui = b.dependency("cimgui", .{
+        .target = target,
+        .optimize = optimize,
+    });
+
+    // inject the cimgui header search path into the sokol C library compile step
+    dep_sokol.artifact("sokol_clib").addIncludePath(dep_cimgui.path(cimgui_conf.include_dir));
+
+    // shaders
+    dep_sokol.artifact("sokol_clib").addIncludePath(b.path("ext/cimgui"));
+    const dep_shdc = dep_sokol.builder.dependency("shdc", .{});
+    const shdc_step = try sokol.shdc.createSourceFile(b, .{
+        .shdc_dep = dep_shdc,
+        .input = "src/shader/quad.glsl",
+        .output = "src/shader/quad.glsl.zig",
+        .slang = .{ .glsl430 = true },
+    });
+
+    // main module with sokol and cimgui imports
+    const mod_main = b.createModule(.{
+        .root_source_file = b.path("src/main.zig"),
+        .target = target,
+        .optimize = optimize,
+        .imports = &.{
+            .{ .name = "sokol", .module = dep_sokol.module("sokol") },
+            .{ .name = cimgui_conf.module_name, .module = dep_cimgui.module(cimgui_conf.module_name) },
+        },
+    });
+    const mod_options = b.addOptions();
+    mod_options.addOption(bool, "docking", opt_docking);
+    mod_main.addOptions("build_options", mod_options);
+
+    // from here on different handling for native vs wasm builds
+    if (target.result.cpu.arch.isWasm()) {
+        try buildWasm(b, .{
+            .mod_main = mod_main,
+            .dep_sokol = dep_sokol,
+            .dep_cimgui = dep_cimgui,
+            .cimgui_clib_name = cimgui_conf.clib_name,
+        });
+    } else {
+        const exe = try buildNative(b, mod_main);
+        exe.step.dependOn(shdc_step);
+    }
+}
+
+fn buildNative(b: *Build, mod: *Build.Module) !*Build.Step.Compile {
+    const exe = b.addExecutable(.{
+        .name = "demo",
+        .root_module = mod,
+    });
+    b.installArtifact(exe);
+    b.step("run", "Run demo").dependOn(&b.addRunArtifact(exe).step);
+    return exe;
+}
+
+const BuildWasmOptions = struct {
+    mod_main: *Build.Module,
+    dep_sokol: *Dependency,
+    dep_cimgui: *Dependency,
+    cimgui_clib_name: []const u8,
+};
+
+fn buildWasm(b: *Build, opts: BuildWasmOptions) !void {
+    // build the main file into a library, this is because the WASM 'exe'
+    // needs to be linked in a separate build step with the Emscripten linker
+    const demo = b.addLibrary(.{
+        .name = "demo",
+        .root_module = opts.mod_main,
+    });
+
+    // get the Emscripten SDK dependency from the sokol dependency
+    const dep_emsdk = opts.dep_sokol.builder.dependency("emsdk", .{});
+
+    // need to inject the Emscripten system header include path into
+    // the cimgui C library otherwise the C/C++ code won't find
+    // C stdlib headers
+    const emsdk_incl_path = dep_emsdk.path("upstream/emscripten/cache/sysroot/include");
+    opts.dep_cimgui.artifact(opts.cimgui_clib_name).addSystemIncludePath(emsdk_incl_path);
+
+    // all C libraries need to depend on the sokol library, when building for
+    // WASM this makes sure that the Emscripten SDK has been setup before
+    // C compilation is attempted (since the sokol C library depends on the
+    // Emscripten SDK setup step)
+    opts.dep_cimgui.artifact(opts.cimgui_clib_name).step.dependOn(&opts.dep_sokol.artifact("sokol_clib").step);
+
+    // create a build step which invokes the Emscripten linker
+    const link_step = try sokol.emLinkStep(b, .{
+        .lib_main = demo,
+        .target = opts.mod_main.resolved_target.?,
+        .optimize = opts.mod_main.optimize.?,
+        .emsdk = dep_emsdk,
+        .use_webgl2 = true,
+        .use_emmalloc = true,
+        .use_filesystem = false,
+        .shell_file_path = opts.dep_sokol.path("src/sokol/web/shell.html"),
+    });
+    // attach to default target
+    b.getInstallStep().dependOn(&link_step.step);
+    // ...and a special run step to start the web build output via 'emrun'
+    const run = sokol.emRunStep(b, .{ .name = "demo", .emsdk = dep_emsdk });
+    run.step.dependOn(&link_step.step);
+    b.step("run", "Run demo").dependOn(&run.step);
+}