add play-opus example

examples/play-opus/App.zig

@@ -0,0 +1,163 @@
+/// Load two opus sound files:
+/// - One long ~3 minute sound file (BGM/Background music) that plays on repeat
+/// - One short sound file (SFX/Sound effect) that plays when you press a key
+const std = @import("std");
+const builtin = @import("builtin");
+
+const mach = @import("mach");
+const assets = @import("assets");
+const opus = @import("opus");
+const gpu = mach.gpu;
+const math = mach.math;
+const sysaudio = mach.sysaudio;
+
+pub const App = @This();
+
+var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+
+pub const name = .app;
+pub const Mod = mach.Mod(@This());
+
+pub const events = .{
+    .init = .{ .handler = init },
+    .deinit = .{ .handler = deinit },
+    .tick = .{ .handler = tick },
+    .audio_state_change = .{ .handler = audioStateChange },
+};
+
+pub const components = .{
+    .is_bgm = .{ .type = void },
+};
+
+sfx: []const f32,
+
+fn init(core: *mach.Core.Mod, audio: *mach.Audio.Mod, app: *Mod) !void {
+    // Initialize audio module, telling it to send our module's .audio_state_change event when an
+    // entity's sound stops playing
+    audio.send(.init, .{app.event(.audio_state_change)});
+
+    const bgm_fbs = std.io.fixedBufferStream(assets.bgm.bit_bit_loop);
+    const sfx_fbs = std.io.fixedBufferStream(assets.sfx.death);
+
+    var sound_stream = std.io.StreamSource{ .const_buffer = bgm_fbs };
+    const bgm = try opus.decodeStream(gpa.allocator(), sound_stream);
+
+    sound_stream = std.io.StreamSource{ .const_buffer = sfx_fbs };
+    const sfx = try opus.decodeStream(gpa.allocator(), sound_stream);
+
+    // Initialize module state
+    app.init(.{ .sfx = sfx.samples });
+
+    const bgm_entity = try audio.newEntity();
+    try app.set(bgm_entity, .is_bgm, {});
+    try audio.set(bgm_entity, .samples, bgm.samples);
+    try audio.set(bgm_entity, .playing, true);
+    try audio.set(bgm_entity, .index, 0);
+
+    std.debug.print("controls:\n", .{});
+    std.debug.print("[typing]     Play SFX\n", .{});
+    std.debug.print("[arrow up]   increase volume 10%\n", .{});
+    std.debug.print("[arrow down] decrease volume 10%\n", .{});
+
+    core.send(.start, .{});
+}
+
+fn deinit(core: *mach.Core.Mod, audio: *mach.Audio.Mod) void {
+    audio.send(.deinit, .{});
+    core.send(.deinit, .{});
+}
+
+fn audioStateChange(
+    audio: *mach.Audio.Mod,
+    app: *Mod,
+) !void {
+    // Find audio entities that are no longer playing
+    var archetypes_iter = audio.entities.query(.{ .all = &.{.{ .mach_audio = &.{.playing} }} });
+    while (archetypes_iter.next()) |archetype| {
+        for (
+            archetype.slice(.entity, .id),
+            archetype.slice(.mach_audio, .playing),
+        ) |id, playing| {
+            if (playing) continue;
+
+            if (app.get(id, .is_bgm)) |_| {
+                // Repeat background music
+                try audio.set(id, .index, 0);
+                try audio.set(id, .playing, true);
+            } else {
+                // Remove the entity for the old sound
+                try audio.removeEntity(id);
+            }
+        }
+    }
+}
+
+fn tick(
+    core: *mach.Core.Mod,
+    audio: *mach.Audio.Mod,
+    app: *Mod,
+) !void {
+    // TODO(Core)
+    var iter = mach.core.pollEvents();
+    while (iter.next()) |event| {
+        switch (event) {
+            .key_press => |ev| switch (ev.key) {
+                .down => {
+                    const vol = math.clamp(try audio.state().player.volume() - 0.1, 0, 1);
+                    try audio.state().player.setVolume(vol);
+                    std.debug.print("[volume] {d:.0}%\n", .{vol * 100.0});
+                },
+                .up => {
+                    const vol = math.clamp(try audio.state().player.volume() + 0.1, 0, 1);
+                    try audio.state().player.setVolume(vol);
+                    std.debug.print("[volume] {d:.0}%\n", .{vol * 100.0});
+                },
+                else => {
+                    // Play a new SFX
+                    const entity = try audio.newEntity();
+                    try audio.set(entity, .samples, app.state().sfx);
+                    try audio.set(entity, .index, 0);
+                    try audio.set(entity, .playing, true);
+                },
+            },
+            .close => core.send(.exit, .{}),
+            else => {},
+        }
+    }
+
+    // Grab the back buffer of the swapchain
+    // TODO(Core)
+    const back_buffer_view = mach.core.swap_chain.getCurrentTextureView().?;
+    defer back_buffer_view.release();
+
+    // Create a command encoder
+    const label = @tagName(name) ++ ".tick";
+    const encoder = core.state().device.createCommandEncoder(&.{ .label = label });
+    defer encoder.release();
+
+    // Begin render pass
+    const sky_blue_background = gpu.Color{ .r = 0.776, .g = 0.988, .b = 1, .a = 1 };
+    const color_attachments = [_]gpu.RenderPassColorAttachment{.{
+        .view = back_buffer_view,
+        .clear_value = sky_blue_background,
+        .load_op = .clear,
+        .store_op = .store,
+    }};
+    const render_pass = encoder.beginRenderPass(&gpu.RenderPassDescriptor.init(.{
+        .label = label,
+        .color_attachments = &color_attachments,
+    }));
+
+    // Draw nothing
+
+    // Finish render pass
+    render_pass.end();
+
+    // Submit our commands to the queue
+    var command = encoder.finish(&.{ .label = label });
+    defer command.release();
+    core.state().queue.submit(&[_]*gpu.CommandBuffer{command});
+
+    // Present the frame
+    core.send(.present_frame, .{});
+}