glfw: add basic example, building+linking on macOS is working

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>

build.zig

@@ -0,0 +1,128 @@
+const std = @import("std");
+const Builder = std.build.Builder;
+
+pub fn build(b: *Builder) void {
+    const mode = b.standardReleaseOptions();
+    const target = b.standardTargetOptions(.{});
+
+    var main_tests = b.addTest("src/main.zig");
+    main_tests.setBuildMode(mode);
+    main_tests.setTarget(target);
+    link(b, main_tests, .{});
+
+    const test_step = b.step("test", "Run library tests");
+    test_step.dependOn(&main_tests.step);
+}
+
+fn thisDir() []const u8 {
+    return std.fs.path.dirname(@src().file) orelse ".";
+}
+
+pub const Options = struct {
+    GLES: bool = false,
+    OpenGL: bool = true,
+    Vulkan: bool = true,
+};
+
+pub fn link(b: *Builder, step: *std.build.LibExeObjStep, options: Options) void {
+    var arena = std.heap.ArenaAllocator.init(b.allocator);
+    defer arena.deinit();
+
+    const lib = b.addStaticLibrary("engine", "src/main.zig");
+    lib.setBuildMode(step.build_mode);
+    lib.setTarget(step.target);
+
+    const target = (std.zig.system.NativeTargetInfo.detect(b.allocator, step.target) catch unreachable).target;
+    switch (target.os.tag) {
+        .windows => {
+            // TODO(slimsag): implement
+            // upstream/glfw/src/win32_thread.c
+            // upstream/glfw/src/wgl_context.c
+            // upstream/glfw/src/win32_init.c
+            // upstream/glfw/src/win32_monitor.c
+            // upstream/glfw/src/win32_time.c
+            // upstream/glfw/src/win32_joystick.c
+            // upstream/glfw/src/win32_window.c
+        },
+        .macos => {
+            var sources = std.ArrayList([]const u8).init(&arena.allocator);
+            for ([_][]const u8{
+                // MacOS-specific sources
+                "upstream/glfw/src/cocoa_joystick.m",
+                "upstream/glfw/src/cocoa_init.m",
+                "upstream/glfw/src/cocoa_window.m",
+                "upstream/glfw/src/cocoa_time.c",
+                "upstream/glfw/src/cocoa_monitor.m",
+                "upstream/glfw/src/nsgl_context.m",
+                "upstream/glfw/src/posix_thread.c",
+
+                // General sources
+                "upstream/glfw/src/monitor.c",
+                // "upstream/glfw/src/null_init.c",
+                // "upstream/glfw/src/null_joystick.c",
+                "upstream/glfw/src/init.c",
+                "upstream/glfw/src/vulkan.c",
+                // "upstream/glfw/src/null_monitor.c",
+                "upstream/glfw/src/input.c",
+                "upstream/glfw/src/osmesa_context.c",
+                // "upstream/glfw/src/null_window.c",
+                "upstream/glfw/src/egl_context.c",
+                "upstream/glfw/src/context.c",
+                "upstream/glfw/src/window.c",
+            }) |path| {
+                var abs_path = std.fs.path.join(&arena.allocator, &.{ thisDir(), path }) catch unreachable;
+                sources.append(abs_path) catch unreachable;
+            }
+            lib.addCSourceFiles(sources.items, &.{"-D_GLFW_COCOA"});
+        },
+        else => {
+            // Assume Linux-like
+            // TODO(slimsag): implement
+
+            // upstream/glfw/src/posix_time.c
+            // upstream/glfw/src/posix_thread.c
+
+            // upstream/glfw/src/wl_monitor.c
+            // upstream/glfw/src/wl_window.c
+            // upstream/glfw/src/wl_init.c
+
+            // upstream/glfw/src/x11_init.c
+            // upstream/glfw/src/x11_window.c
+            // upstream/glfw/src/x11_monitor.c
+            // upstream/glfw/src/xkb_unicode.c
+
+            // upstream/glfw/src/linux_joystick.c
+            // upstream/glfw/src/glx_context.c
+        },
+    }
+    linkGLFW(b, lib, options);
+    lib.install();
+
+    step.linkLibrary(lib);
+    linkGLFW(b, step, options);
+}
+
+fn linkGLFW(b: *Builder, step: *std.build.LibExeObjStep, options: Options) void {
+    var include_dir = std.fs.path.join(b.allocator, &.{ thisDir(), "upstream/glfw/include" }) catch unreachable;
+    defer b.allocator.free(include_dir);
+    step.addIncludeDir(include_dir);
+
+    const target = (std.zig.system.NativeTargetInfo.detect(b.allocator, step.target) catch unreachable).target;
+    switch (target.os.tag) {
+        .windows => {},
+        .macos => {
+            step.linkFramework("Cocoa");
+            step.linkFramework("IOKit");
+            step.linkFramework("CoreFoundation");
+            if (options.GLES) {
+                step.linkSystemLibrary("GLESv2");
+            }
+            if (options.OpenGL) {
+                step.linkFramework("OpenGL");
+            }
+        },
+        else => {
+            // Assume Linux-like
+        },
+    }
+}

src/main.zig

@@ -0,0 +1,28 @@
+const std = @import("std");
+const testing = std.testing;
+
+const c = @cImport(@cInclude("GLFW/glfw3.h"));
+
+pub fn basicTest() void {
+    if (c.glfwInit() != c.GLFW_TRUE) {
+        @panic("failed to init");
+    }
+    const window = c.glfwCreateWindow(640, 480, "GLFW example", null, null);
+    if (window == null)
+    {
+        c.glfwTerminate();
+        @panic("failed to create window");
+    }
+
+    var start = std.time.milliTimestamp();
+    while (std.time.milliTimestamp() < start+3000 and c.glfwWindowShouldClose(window) != c.GLFW_TRUE) {
+        c.glfwPollEvents();
+    }
+
+    c.glfwDestroyWindow(window);
+    c.glfwTerminate();
+}
+
+test "basic" {
+    basicTest();
+}