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An extremely basic PPM viewer in Zig + Vulkan
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// Although this function looks imperative, it does not perform the build// directly and instead it mutates the build graph (`b`) that will be then// executed by an external runner. The functions in `std.Build` implement a DSL// for defining build steps and express dependencies between them, allowing the// build runner to parallelize the build automatically (and the cache system to// know when a step doesn't need to be re-run).pub fn build(b: *std.Build) void { // Standard target options allow the person running `zig build` to choose // what target to build for. Here we do not override the defaults, which // means any target is allowed, and the default is native. Other options // for restricting supported target set are available. const target = b.standardTargetOptions(.{}); // Standard optimization options allow the person running `zig build` to select // between Debug, ReleaseSafe, ReleaseFast, and ReleaseSmall. Here we do not // set a preferred release mode, allowing the user to decide how to optimize. const optimize = b.standardOptimizeOption(.{});
const GPUBackend = @import("knots").GPUBackend;
const knots = b.dependency("knots", .{ .target = target, .optimize = optimize, .gpu_backend = GPUBackend.vulkan }); // It's also possible to define more custom flags to toggle optional features // of this build script using `b.option()`. All defined flags (including // target and optimize options) will be listed when running `zig build --help` // in this directory.
// This creates a module, which represents a collection of source files alongside // some compilation options, such as optimization mode and linked system libraries. // Zig modules are the preferred way of making Zig code available to consumers. // addModule defines a module that we intend to make available for importing // to our consumers. We must give it a name because a Zig package can expose // multiple modules and consumers will need to be able to specify which // module they want to access. const mod = b.addModule("ppmview", .{ // The root source file is the "entry point" of this module. Users of // this module will only be able to access public declarations contained // in this file, which means that if you have declarations that you // intend to expose to consumers that were defined in other files part // of this module, you will have to make sure to re-export them from // the root file. .root_source_file = b.path("src/root.zig"), // Later on we'll use this module as the root module of a test executable // which requires us to specify a target. .target = target, });
// Here we define an executable. An executable needs to have a root module // which needs to expose a `main` function. While we could add a main function // to the module defined above, it's sometimes preferable to split business // logic and the CLI into two separate modules. // // If your goal is to create a Zig library for others to use, consider if // it might benefit from also exposing a CLI tool. A parser library for a // data serialization format could also bundle a CLI syntax checker, for example. // // If instead your goal is to create an executable, consider if users might // be interested in also being able to embed the core functionality of your // program in their own executable in order to avoid the overhead involved in // subprocessing your CLI tool. // // If neither case applies to you, feel free to delete the declaration you // don't need and to put everything under a single module. const exe = b.addExecutable(.{ .name = "ppmview", .root_module = b.createModule(.{ // b.createModule defines a new module just like b.addModule but, // unlike b.addModule, it does not expose the module to consumers of // this package, which is why in this case we don't have to give it a name. .root_source_file = b.path("src/main.zig"), // Target and optimization levels must be explicitly wired in when // defining an executable or library (in the root module), and you // can also hardcode a specific target for an executable or library // definition if desireable (e.g. firmware for embedded devices). .target = target, .optimize = optimize, // List of modules available for import in source files part of the // root module. .imports = &.{ // Here "ppmview" is the name you will use in your source code to // import this module (e.g. `@import("ppmview")`). The name is // repeated because you are allowed to rename your imports, which // can be extremely useful in case of collisions (which can happen // importing modules from different packages). .{ .name = "ppmview", .module = mod }, .{ .name = "knots", .module = knots.module("knots") }, }, }), });
// This declares intent for the executable to be installed into the // install prefix when running `zig build` (i.e. when executing the default // step). By default the install prefix is `zig-out/` but can be overridden // by passing `--prefix` or `-p`. b.installArtifact(exe);
// This creates a top level step. Top level steps have a name and can be // invoked by name when running `zig build` (e.g. `zig build run`). // This will evaluate the `run` step rather than the default step. // For a top level step to actually do something, it must depend on other // steps (e.g. a Run step, as we will see in a moment). const run_step = b.step("run", "Run the app");
// This creates a RunArtifact step in the build graph. A RunArtifact step // invokes an executable compiled by Zig. Steps will only be executed by the // runner if invoked directly by the user (in the case of top level steps) // or if another step depends on it, so it's up to you to define when and // how this Run step will be executed. In our case we want to run it when // the user runs `zig build run`, so we create a dependency link. const run_cmd = b.addRunArtifact(exe); run_step.dependOn(&run_cmd.step);
// By making the run step depend on the default step, it will be run from the // installation directory rather than directly from within the cache directory. run_cmd.step.dependOn(b.getInstallStep());
// This allows the user to pass arguments to the application in the build // command itself, like this: `zig build run -- arg1 arg2 etc` //run_cmd.addPassthruArgs();
// Creates an executable that will run `test` blocks from the provided module. // Here `mod` needs to define a target, which is why earlier we made sure to // set the releative field. const mod_tests = b.addTest(.{ .root_module = mod, });
// A run step that will run the test executable. const run_mod_tests = b.addRunArtifact(mod_tests);
// Creates an executable that will run `test` blocks from the executable's // root module. Note that test executables only test one module at a time, // hence why we have to create two separate ones. const exe_tests = b.addTest(.{ .root_module = exe.root_module, });
// A run step that will run the second test executable. const run_exe_tests = b.addRunArtifact(exe_tests);
// A top level step for running all tests. dependOn can be called multiple // times and since the two run steps do not depend on one another, this will // make the two of them run in parallel. const test_step = b.step("test", "Run tests"); test_step.dependOn(&run_mod_tests.step); test_step.dependOn(&run_exe_tests.step);
// Just like flags, top level steps are also listed in the `--help` menu. // // The Zig build system is entirely implemented in userland, which means // that it cannot hook into private compiler APIs. All compilation work // orchestrated by the build system will result in other Zig compiler // subcommands being invoked with the right flags defined. You can observe // these invocations when one fails (or you pass a flag to increase // verbosity) to validate assumptions and diagnose problems. // // Lastly, the Zig build system is relatively simple and self-contained, // and reading its source code will allow you to master it.}