Add GUI module

.vscode/launch.json

@@ -5,7 +5,7 @@
 			"name": "Runner",
 			"type": "gdb",
 			"request": "launch",
-			"target": "${workspaceRoot}/demos/effects.out",
+			"target": "${workspaceRoot}/demos/canvas.out",
 			"cwd": "${workspaceRoot}/demos/",
 			"valuesFormatting": "prettyPrinters",
 			"preLaunchTask": "Build All"

build.zig

@@ -254,6 +254,20 @@ pub fn build(b: *std.Build) !void {
 
 	gfx_module.link_libc = true;
 
+	_ = try project.add_module(b, "gui", .{
+		.imports = &.{
+			.{
+				.name = "ona",
+				.module = ona_module,
+			},
+
+			.{
+				.name = "gfx",
+				.module = gfx_module,
+			},
+		},
+	});
+
 	project.find_demos(b.step("demos", "Build demos"));
 	project.find_tests(b.step("tests", "Build and run tests"));
 }

demos/canvas.zig

@@ -0,0 +1,31 @@
+const gfx = @import("gfx");
+
+const gui = @import("gui");
+
+const hid = @import("hid");
+
+const ona = @import("ona");
+
+pub const main = ona.App.game
+	.with_module(gfx)
+	.with_module(hid)
+	.with_module(gui)
+	.with_system(.load, ona.system_fn(load), .{ .label = "Hello Ona" }).build();
+
+pub fn load(canvas: ona.Write(gui.Canvas)) !void {
+	const item = try canvas.state.append("", .{
+		.left = 0,
+		.top = 0,
+		.width = 256,
+		.height = 256,
+	});
+
+	canvas.state.set_block(item, .{
+		.has_background = .default,
+		.has_color = gfx.colors.purple,
+	});
+
+	try canvas.state.set_label(item, .{
+		.has_text = "Hello, world",
+	});
+}

demos/effects.zig

@@ -56,23 +56,23 @@ fn load(display: ona.Write(gfx.Display), effects: ona.Write(Effects), assets: on
 	};
 }
 
-pub const main = ona.App.setup.
+pub const main = ona.App.game
-	with_module(gfx).
+	.with_module(gfx)
-	with_state(Effects{}).
+	.with_state(Effects{})
-	with_system(.load, ona.system_fn(load), .{.label = "load effects"}).
+	.with_system(.load, ona.system_fn(load), .{.label = "load effects"})
-	with_system(.update, ona.system_fn(update), .{.label = "update effects"}).
+	.with_system(.update, ona.system_fn(update), .{.label = "update effects"})
-	with_system(.render, ona.system_fn(render), .{.label = "render effects"}).build();
+	.with_system(.render, ona.system_fn(render), .{.label = "render effects"}).build();
 
-fn update(effects: ona.Write(Effects), app: ona.Read(ona.App)) void {
+fn update(effects: ona.Write(Effects), loop: ona.Read(ona.Loop)) void {
 	const update_seconds = 5;
 
-	if ((app.state.elapsed_time - effects.state.last_time) > update_seconds) {
+	if ((loop.state.elapsed_time - effects.state.last_time) > update_seconds) {
 		effects.state.image_index = (effects.state.image_index + 1) % effects.state.image_textures.len;
-		effects.state.last_time = app.state.elapsed_time;
+		effects.state.last_time = loop.state.elapsed_time;
 	}
 }
 
-fn render(commands: gfx.Commands, effects: ona.Write(Effects), app: ona.Read(ona.App), display: ona.Write(gfx.Display)) !void {
+fn render(commands: gfx.Commands(.background), effects: ona.Write(Effects), loop: ona.Read(ona.Loop), display: ona.Write(gfx.Display)) !void {
 	try commands.set_target(.{
 		.texture = effects.state.render_texture,
 		.clear_color = gfx.colors.black,
@@ -80,26 +80,21 @@ fn render(commands: gfx.Commands, effects: ona.Write(Effects), app: ona.Read(ona
 		.clear_stencil = 0,
 	});
 
-	const display_width: f32 = @floatFromInt(display.state.width);
+	const width: f32 = @floatFromInt(display.state.width);
-	const display_height: f32 = @floatFromInt(display.state.height);
+	const height: f32 = @floatFromInt(display.state.height);
-
-	const display_transform = gfx.transform_2d(.{
-		.translation = .{display_width / 2, display_height / 2},
-	});
 
 	try commands.draw_texture(.{
 		.texture = effects.state.image_textures[effects.state.image_index],
-		.transform = display_transform,
+		.size = .{width, height},
-		.resolution = .{display.state.width, display.state.height},
 	});
 
 	try commands.set_effect(.{
 		.effect = effects.state.crt_effect,
 
 		.properties = std.mem.asBytes(&CRT{
-			.width = display_width,
+			.width = width,
-			.height = display_height,
+			.height = height,
-			.time = @floatCast(app.state.elapsed_time),
+			.time = @floatCast(loop.state.elapsed_time),
 		}),
 	});
 
@@ -111,7 +106,7 @@ fn render(commands: gfx.Commands, effects: ona.Write(Effects), app: ona.Read(ona
 
 	try commands.draw_texture(.{
 		.texture = effects.state.render_texture,
-		.transform = display_transform,
+		.size = .{width, height},
 	});
 }
 

demos/inputs.zig

@@ -9,7 +9,8 @@ const std = @import("std");
 const Spawned = struct {
 	visual: struct {
 		color: gfx.Color,
-		transform: gfx.Transform2D,
+		position: gfx.Vector2,
+		rotation: f32,
 	},
 
 	lifetime_seconds: f32,
@@ -23,7 +24,6 @@ const Visuals = struct {
 
 fn cleanup(visuals: ona.Write(Visuals)) !void {
 	visuals.state.spawned.deinit();
-	visuals.state.spawned.deinit();
 }
 
 fn load(visuals: ona.Write(Visuals)) !void {
@@ -32,14 +32,14 @@ fn load(visuals: ona.Write(Visuals)) !void {
 	try visuals.state.spawned.grow(initial_spawn_capacity);
 }
 
-pub const main = ona.App.setup.
+pub const main = ona.App.game
-	with_module(gfx).
+	.with_module(gfx)
-	with_module(hid).
+	.with_module(hid)
-	with_state(Visuals{.random = std.Random.Xoroshiro128.init(47342563891212)}).
+	.with_state(Visuals{.random = std.Random.Xoroshiro128.init(47342563891212)})
-	with_system(.load, ona.system_fn(load), .{.label = "load visuals"}).
+	.with_system(.load, ona.system_fn(load), .{.label = "load visuals"})
-	with_system(.update, ona.system_fn(update), .{.label = "spawn visuals"}).
+	.with_system(.update, ona.system_fn(update), .{.label = "spawn visuals"})
-	with_system(.render, ona.system_fn(render), .{.label = "render visuals"}).
+	.with_system(.render, ona.system_fn(render), .{.label = "render visuals"})
-	with_system(.exit, ona.system_fn(cleanup), .{.label = "clean up visuals"}).build();
+	.with_system(.exit, ona.system_fn(cleanup), .{.label = "clean up visuals"}).build();
 
 fn update(visuals: ona.Write(Visuals), events: ona.Receive(hid.Event), display: ona.Read(gfx.Display)) !void {
 	update_spawned(&visuals.state.spawned);
@@ -47,7 +47,6 @@ fn update(visuals: ona.Write(Visuals), events: ona.Receive(hid.Event), display:
 	const random = visuals.state.random.random();
 	const width: f32 = @floatFromInt(display.state.width);
 	const height: f32 = @floatFromInt(display.state.height);
-	const icon_scale = .{8, 8};
 
 	for (events.messages()) |event| {
 		switch (event) {
@@ -57,12 +56,8 @@ fn update(visuals: ona.Write(Visuals), events: ona.Receive(hid.Event), display:
 
 					.visual = .{
 						.color = .{random.float(f32), random.float(f32), random.float(f32), random.float(f32)},
-
+						.position = .{width * random.float(f32), height},
-						.transform = gfx.transform_2d(.{
-							.translation = .{width * random.float(f32), height},
 						.rotation = std.math.pi * random.float(f32),
-							.scale = icon_scale,
-						}),
 					},
 				});
 			},
@@ -73,12 +68,8 @@ fn update(visuals: ona.Write(Visuals), events: ona.Receive(hid.Event), display:
 
 					.visual = .{
 						.color = .{random.float(f32), random.float(f32), random.float(f32), random.float(f32)},
-
+						.position = visuals.state.mouse_position,
-						.transform = gfx.transform_2d(.{
-							.translation = visuals.state.mouse_position,
 						.rotation = std.math.pi * random.float(f32),
-							.scale = icon_scale,
-						}),
 					},
 				});
 			},
@@ -96,7 +87,7 @@ fn update_spawned(spawned: *ona.stack.Parallel(Spawned)) void {
 	const float_speed = 6;
 
 	for (spawned.values.slice(.visual)) |*visual| {
-		visual.transform = visual.transform.translated(.{0, -float_speed});
+		visual.position -= .{0, float_speed};
 	}
 
 	{
@@ -119,11 +110,13 @@ fn update_spawned(spawned: *ona.stack.Parallel(Spawned)) void {
 	}
 }
 
-fn render(visuals: ona.Write(Visuals), commands: gfx.Commands) !void {
+fn render(visuals: ona.Write(Visuals), commands: gfx.Commands(.foreground)) !void {
 	for (visuals.state.spawned.values.slice(.visual)) |visual| {
-		try commands.draw_rect(.{
+		try commands.draw_texture(.{
-			.transform = visual.transform,
+			.anchor = @splat(0.5),
-			.color = visual.color,
+			.position = visual.position,
+			.tint = visual.color,
+			.size = @as(gfx.Vector2, @splat(64)),
 		});
 	}
 }

src/gfx/Resources.zig

@@ -38,7 +38,7 @@ pub const Effect = struct {
 			},
 
 			.vertex_source = .{
-				.ops = &spirv.to_ops(@embedFile("./shaders/2d_default.vert.spv")),
+				.ops = &spirv.to_ops(@embedFile("./shaders/draw_texture.vert.spv")),
 			},
 
 			.fragment_source = .{
@@ -197,12 +197,12 @@ pub const Effect = struct {
 			};
 
 			attrs[2] = .{
-				.format = .FLOAT2,
+				.format = .FLOAT,
 				.buffer_index = 1,
 			};
 
 			attrs[3] = .{
-				.format = .FLOAT2,
+				.format = .FLOAT,
 				.buffer_index = 1,
 			};
 
@@ -212,12 +212,12 @@ pub const Effect = struct {
 			};
 
 			attrs[5] = .{
-				.format = .UBYTE4N,
+				.format = .FLOAT2,
 				.buffer_index = 1,
 			};
 
 			attrs[6] = .{
-				.format = .FLOAT,
+				.format = .FLOAT2,
 				.buffer_index = 1,
 			};
 
@@ -226,6 +226,11 @@ pub const Effect = struct {
 				.buffer_index = 1,
 			};
 
+			attrs[8] = .{
+				.format = .FLOAT4,
+				.buffer_index = 1,
+			};
+
 			break: get attrs;
 		},
 
@@ -466,7 +471,7 @@ pub fn init() !Self {
 	}
 
 	assert.is_default_handle(try pools.create_effect(.{
-		.fragment_spirv_ops = &spirv.to_ops(@embedFile("./shaders/2d_default.frag.spv")),
+		.fragment_spirv_ops = &spirv.to_ops(@embedFile("./shaders/draw_texture.frag.spv")),
 	}));
 
 	assert.is_default_handle(try pools.create_texture(try descs.solid_texture(.{

src/gfx/gfx.zig

@@ -27,40 +27,7 @@ pub const Assets = struct {
 		load_file: *const fn (*std.heap.ArenaAllocator, ona.files.Storage, []const u8) LoadFileError!Texture.Desc,
 	};
 
-	pub const WorkQueue = ona.asyncio.BlockingQueue(1024, union (enum) {
+	pub const WorkQueue = ona.asyncio.BlockingQueue(1024, Work);
-		load_effect: LoadEffectWork,
-		load_texture: LoadTextureWork,
-		render_frame: RenderFrameWork,
-		shutdown,
-		unload_effect: UnloadEffectWork,
-		unload_texture: UnloadTextureWork,
-
-		const LoadEffectWork = struct {
-			desc: Effect.Desc,
-			loaded: *ona.asyncio.Future(std.mem.Allocator.Error!Effect),
-		};
-
-		const LoadTextureWork = struct {
-			desc: Texture.Desc,
-			loaded: *ona.asyncio.Future(std.mem.Allocator.Error!Texture),
-		};
-
-		const RenderFrameWork = struct {
-			clear_color: Color,
-			width: u16,
-			height: u16,
-			finished: *std.Thread.ResetEvent,
-			has_command_params: ?*ona.Params(Commands).Node,
-		};
-
-		const UnloadEffectWork = struct {
-			handle: Effect,
-		};
-
-		const UnloadTextureWork = struct {
-			handle: Texture,
-		};
-	});
 
 	fn deinit(self: *Assets) void {
 		self.pending_work.enqueue(.shutdown);
@@ -72,12 +39,10 @@ pub const Assets = struct {
 		self.* = undefined;
 	}
 
-	fn init() !Assets {
+	fn init(width: u16, height: u16) !Assets {
 		const window = create: {
 			const position = ext.SDL_WINDOWPOS_CENTERED;
 			const flags = ext.SDL_WINDOW_OPENGL;
-			const width = 640;
-			const height = 480;
 
 			break: create ext.SDL_CreateWindow("Ona", position, position, width, height, flags) orelse {
 				return error.Unsupported;
@@ -138,42 +103,60 @@ pub const Assets = struct {
 	}
 
 	pub const thread_restriction = .main;
+
+	pub fn unload_effect(self: *Assets, handle: Effect) void {
+		self.pending_work.enqueue(.{.unload_effect = handle});
+	}
+
+	pub fn unload_texture(self: *Assets, handle: Texture) void {
+		self.pending_work.enqueue(.{.unload_texture = handle});
+	}
 };
 
 pub const Color = @Vector(4, f32);
 
-pub const Commands = struct {
-	pending: *List,
-
 pub const Command = union (enum) {
-		draw_rect: DrawRectCommand,
+	draw_font: DrawFont,
-		draw_texture: DrawTextureCommand,
+	draw_texture: DrawTexture,
-		set_effect: SetEffectCommand,
+	set_effect: SetEffect,
-		set_target: SetTargetCommand,
+	set_target: SetTarget,
+
+	pub const DrawFont = struct {
+		position: Vector2 = @splat(0),
+		size: Vector2,
+		text: []const u8,
+		font: Font,
+		tint: Color,
+		depth: f32,
 	};
 
-	pub const DrawRectCommand = struct {
+	pub const DrawTexture = struct {
-		color: Color,
+		anchor: Vector2 = @splat(0),
-		transform: Transform2D,
+		size: ?Vector2 = null,
+		source: Rect = .{.left = 0, .top = 0, .right = 1, .bottom = 1},
+		position: Vector2 = @splat(0),
+		tint: Color = colors.white,
+		texture: Texture = .default,
+		rotation: f32 = 0,
+		depth: f32 = 0,
 	};
 
-	pub const DrawTextureCommand = struct {
+	pub const SetEffect = struct {
-		texture: Texture,
-		transform: Transform2D,
-		resolution: ?@Vector(2, u16) = null,
-	};
-
-	pub const SetEffectCommand = struct {
 		effect: Effect,
 		properties: []const u8,
 	};
 
-	pub const SetTargetCommand = struct {
+	pub const SetTarget = struct {
 		texture: ?Texture = null,
 		clear_color: ?Color,
 		clear_depth: ?f32,
 		clear_stencil: ?u8,
 	};
+};
+
+pub fn Commands(comptime layer: Layer) type {
+	return struct {
+		pending: *List,
 
 		pub const List = struct {
 			arena: std.heap.ArenaAllocator,
@@ -231,6 +214,8 @@ pub const Commands = struct {
 			}
 		};
 
+		const Self = @This();
+
 		pub fn bind(_: ona.World.BindContext) std.mem.Allocator.Error!Param {
 			return .{
 				.swap_lists = .{
@@ -240,21 +225,30 @@ pub const Commands = struct {
 			};
 		}
 
-	pub fn init(param: *Param) Commands {
+		pub fn init(param: *Param) Self {
 			return .{
 				.pending = param.pending_list(),
 			};
 		}
 
-	pub fn draw_rect(self: Commands, command: DrawRectCommand) std.mem.Allocator.Error!void {
+		pub fn draw_font(self: Self, command: Command.DrawFont) std.mem.Allocator.Error!void {
-		try self.pending.stack.push_grow(.{.draw_rect = command});
+			try self.pending.stack.push_grow(.{
+				.draw_font = .{
+					.text = try self.pending.arena.allocator().dupe(u8, command.text),
+					.position = command.position,
+					.size = command.size,
+					.font = command.font,
+					.tint = command.tint,
+					.depth = command.depth,
+				},
+			});
 		}
 
-	pub fn draw_texture(self: Commands, command: DrawTextureCommand) std.mem.Allocator.Error!void {
+		pub fn draw_texture(self: Self, command: Command.DrawTexture) std.mem.Allocator.Error!void {
 			try self.pending.stack.push_grow(.{.draw_texture = command});
 		}
 
-	pub fn set_effect(self: Commands, command: SetEffectCommand) std.mem.Allocator.Error!void {
+		pub fn set_effect(self: Self, command: Command.SetEffect) std.mem.Allocator.Error!void {
 			try self.pending.stack.push_grow(.{
 				.set_effect = .{
 					.properties = try self.pending.arena.allocator().dupe(u8, command.properties),
@@ -263,14 +257,17 @@ pub const Commands = struct {
 			});
 		}
 
+		pub const _ = layer;
+
 		pub fn unbind(param: *Param, _: ona.World.UnbindContext) void {
 			param.deinit();
 		}
 
-	pub fn set_target(self: Commands, command: SetTargetCommand) std.mem.Allocator.Error!void {
+		pub fn set_target(self: Self, command: Command.SetTarget) std.mem.Allocator.Error!void {
 			try self.pending.stack.push_grow(.{.set_target = command});
 		}
 	};
+}
 
 pub const Descs = struct {
 	arena: std.heap.ArenaAllocator,
@@ -431,7 +428,24 @@ pub const Effect = enum (u32) {
 	};
 };
 
-pub const Rect = struct {
+pub const Font = enum (u32) {
+	default,
+	_,
+
+	pub const Desc = struct {
+
+	};
+};
+
+pub const Layer = enum {
+	background,
+	foreground,
+	overlay,
+
+	const values = std.enums.values(Layer);
+};
+
+pub const Rect = extern struct {
 	left: f32,
 	top: f32,
 	right: f32,
@@ -474,58 +488,47 @@ pub const Texture = enum (u32) {
 	};
 };
 
-pub const Transform2D = extern struct {
+pub const Vector2 = @Vector(2, f32);
-	xbasis: Vector = .{1, 0},
-	ybasis: Vector = .{0, 1},
-	origin: Vector = @splat(0),
 
-	pub const Simplified = struct {
+const Work = union (enum) {
-		translation: Vector = @splat(0),
+	load_effect: LoadEffect,
-		rotation: f32 = 0,
+	load_texture: LoadTexture,
-		scale: Vector = @splat(1),
+	render_frame: RenderFrame,
-		skew: f32 = 0,
+	shutdown,
+	unload_effect: UnloadEffect,
+	unload_texture: UnloadTexture,
+
+	const LoadEffect = struct {
+		desc: Effect.Desc,
+		loaded: *ona.asyncio.Future(std.mem.Allocator.Error!Effect),
 	};
 
-	pub const Vector = @Vector(2, f32);
+	const LoadTexture = struct {
-
+		desc: Texture.Desc,
-	pub fn scaled(self: Transform2D, scale: Vector) Transform2D {
+		loaded: *ona.asyncio.Future(std.mem.Allocator.Error!Texture),
-		var transform = self;
-		const scale_x, const scale_y = scale;
-
-		transform.xbasis *= @splat(scale_x);
-        transform.ybasis *= @splat(scale_y);
-
-		return transform;
-	}
-
-	pub fn transformed(self: Transform2D, other: Transform2D) Transform2D {
-		const xbasis_x, const xbasis_y = other.xbasis;
-		const ybasis_x, const ybasis_y = other.ybasis;
-		const origin_x, const origin_y = other.origin;
-
-		return .{
-			.xbasis =
-				(self.xbasis * @as(Vector, @splat(xbasis_x))) +
-				(self.ybasis * @as(Vector, @splat(xbasis_y))),
-
-			.ybasis =
-				(self.xbasis * @as(Vector, @splat(ybasis_x))) +
-				(self.ybasis * @as(Vector, @splat(ybasis_y))),
-
-			.origin =
-				(self.xbasis * @as(Vector, @splat(origin_x))) +
-				(self.ybasis * @as(Vector, @splat(origin_y))) +
-				self.origin,
 	};
-	}
 
-	pub fn translated(self: Transform2D, translation: Vector) Transform2D {
+	const RenderFrame = struct {
-		var transform = self;
+		clear_color: Color,
+		width: u16,
+		height: u16,
+		finished: *std.Thread.ResetEvent,
+		commands_set: CommandsSet,
 
-		transform.origin += translation;
+		const CommandsSet = struct {
+			?*ona.Params(Commands(.background)).Node,
+			?*ona.Params(Commands(.foreground)).Node,
+			?*ona.Params(Commands(.overlay)).Node,
+		};
+	};
 
-		return transform;
+	const UnloadEffect = struct {
-	}
+		handle: Effect,
+	};
+
+	const UnloadTexture = struct {
+		handle: Texture,
+	};
 };
 
 pub const colors = struct {
@@ -546,6 +549,8 @@ pub const colors = struct {
 
 	pub const purple = rgb(0.5, 0, 0.5);
 
+	pub const red = rgb(1, 0, 0);
+
 	pub fn rgb(r: f32, g: f32, b: f32) Color {
 		return .{r, g, b, 1};
 	}
@@ -553,13 +558,13 @@ pub const colors = struct {
 	pub const white = greyscale(1);
 };
 
-pub fn poll(app: ona.Write(ona.App), events: ona.Send(hid.Event)) !void {
+pub fn poll(loop: ona.Write(ona.Loop), events: ona.Send(hid.Event)) !void {
 	var event = @as(ext.SDL_Event, undefined);
 
 	while (ext.SDL_PollEvent(&event) != 0) {
 		switch (event.type) {
 			ext.SDL_QUIT => {
-				app.state.quit();
+				loop.state.quit();
 			},
 
 			ext.SDL_KEYUP => {
@@ -606,13 +611,15 @@ pub fn poll(app: ona.Write(ona.App), events: ona.Send(hid.Event)) !void {
 	}
 }
 
-pub fn setup(world: *ona.World, events: ona.App.Events) (error {Unsupported} || std.Thread.SpawnError || std.mem.Allocator.Error)!void {
+pub fn setup(world: *ona.World) !void {
 	if (ext.SDL_Init(ext.SDL_INIT_VIDEO | ext.SDL_INIT_EVENTS) != 0) {
 		return error.Unsupported;
 	}
 
+	const display = try world.set_get_state(Display{});
+
 	const assets = create: {
-		var assets = try Assets.init();
+		var assets = try Assets.init(display.width, display.height);
 
 		errdefer {
 			assets.deinit();
@@ -632,10 +639,9 @@ pub fn setup(world: *ona.World, events: ona.App.Events) (error {Unsupported} ||
 		assets.window,
 	});
 
-	try world.set_state(Display{});
+	try world.on_event(.pre_update, ona.system_fn(poll), .{.label = "poll gfx"});
-	try world.on_event(events.pre_update, ona.system_fn(poll), .{.label = "poll gfx"});
+	try world.on_event(.exit, ona.system_fn(stop), .{.label = "stop gfx"});
-	try world.on_event(events.exit, ona.system_fn(stop), .{.label = "stop gfx"});
+	try world.on_event(.finish, ona.system_fn(synchronize), .{.label = "synchronize gfx"});
-	try world.on_event(events.finish, ona.system_fn(synchronize), .{.label = "synchronize gfx"});
 }
 
 pub fn stop(assets: ona.Write(Assets)) void {
@@ -648,8 +654,8 @@ pub fn synchronize(exclusive: ona.Exclusive(&.{Assets, Display})) !void {
 	assets.frame_rendered.wait();
 	assets.frame_rendered.reset();
 
-	{
+	inline for (Layer.values) |layer| {
-		var has_command_param = exclusive.world.get_params(Commands).has_head;
+		var has_command_param = exclusive.world.get_params(Commands(layer)).has_head;
 
 		while (has_command_param) |command_param| : (has_command_param = command_param.has_next) {
 			command_param.param.rotate();
@@ -664,35 +670,27 @@ pub fn synchronize(exclusive: ona.Exclusive(&.{Assets, Display})) !void {
 		ext.SDL_SetWindowSize(assets.window, display.width, display.height);
 	}
 
-	if (exclusive.world.get_params(Commands).has_head) |command_param| {
+	var commands_filled: usize = 0;
+	var commands_set = Work.RenderFrame.CommandsSet{null, null, null};
+
+	inline for (0 .. Layer.values.len, Layer.values) |i, layer| {
+		if (exclusive.world.get_params(Commands(layer)).has_head) |command_param| {
+			commands_set[i] = command_param;
+			commands_filled += 1;
+		}
+	}
+
+	if (commands_filled == 0) {
+		assets.frame_rendered.set();
+	} else {
 		assets.pending_work.enqueue(.{
 			.render_frame = .{
-				.has_command_params = command_param,
+				.commands_set = commands_set,
 				.width = display.width,
 				.height = display.height,
 				.clear_color = display.clear_color,
 				.finished = &assets.frame_rendered,
 			},
 		});
-	} else {
-		assets.frame_rendered.set();
 	}
 }
-
-pub fn transform_2d(simplified: Transform2D.Simplified) Transform2D {
-	const rotation_skew = simplified.rotation + simplified.skew;
-
-	return .{
-		.xbasis = simplified.scale * Transform2D.Vector{
-			std.math.cos(simplified.rotation),
-			std.math.sin(simplified.rotation),
-		},
-
-		.ybasis = simplified.scale * Transform2D.Vector{
-			-std.math.sin(rotation_skew),
-			std.math.cos(rotation_skew),
-		},
-
-		.origin = simplified.translation,
-	};
-}

src/gfx/rendering.zig

@@ -23,15 +23,23 @@ const Frame = struct {
 	current_source_texture: gfx.Texture = .default,
 	current_target_texture: ?gfx.Texture = null,
 	current_effect: gfx.Effect = .default,
+	transform_matrix: Matrix = identity_matrix,
 	width: u16 = 0,
 	height: u16 = 0,
 
 	const DrawTexture = extern struct {
-		transform: gfx.Transform2D,
+		rotation: f32,
-		tint: @Vector(4, u8) = @splat(std.math.maxInt(u8)),
+		depth: f32,
-		depth: f32 = 0,
+		position: gfx.Vector2,
-		texture_offset: @Vector(2, f32) = @splat(0),
+		size: gfx.Vector2,
-		texture_size: @Vector(2, f32) = @splat(1),
+		anchor: gfx.Vector2,
+		source_clip: gfx.Rect,
+		tint: gfx.Color,
+	};
+
+	const View = extern struct {
+		projection_matrix: Matrix,
+		transform_matrix: Matrix,
 	};
 
 	const batches_per_buffer = 512;
@@ -75,35 +83,13 @@ const Frame = struct {
 		};
 	}
 
-	pub fn draw_rect(self: *Frame, resources: *Resources, command: gfx.Commands.DrawRectCommand) !void {
+	pub fn draw_font(self: *Frame, resources: *Resources, command: gfx.Command.DrawFont) !void {
-		if (self.current_source_texture != .default) {
+		_ = self;
-			self.flush(resources);
+		_ = resources;
+		_ = command;
 	}
 
-		self.current_source_texture = .default;
+	pub fn draw_texture(self: *Frame, resources: *Resources, command: gfx.Command.DrawTexture) !void {
-
-		const has_filled_current_buffer = (self.drawn_count % batches_per_buffer) == 0;
-		const buffer_count = self.drawn_count / batches_per_buffer;
-
-		if (has_filled_current_buffer and buffer_count == self.texture_batch_buffers.len()) {
-			const instance_buffer = sokol.gfx.makeBuffer(.{
-				.size = @sizeOf(DrawTexture) * batches_per_buffer,
-				.usage = .STREAM,
-			});
-
-			errdefer sokol.gfx.destroyBuffer(instance_buffer);
-
-			try self.texture_batch_buffers.push_grow(instance_buffer);
-		}
-
-		_ = sokol.gfx.appendBuffer(self.texture_batch_buffers.get().?.*, sokol.gfx.asRange(&DrawTexture{
-			.transform = command.transform,
-		}));
-
-		self.drawn_count += 1;
-	}
-
-	pub fn draw_texture(self: *Frame, resources: *Resources, command: gfx.Commands.DrawTextureCommand) !void {
 		if (self.current_source_texture != command.texture) {
 			self.flush(resources);
 		}
@@ -127,10 +113,13 @@ const Frame = struct {
 		const texture = resources.get_texture(command.texture).?;
 
 		_ = sokol.gfx.appendBuffer(self.texture_batch_buffers.get().?.*, sokol.gfx.asRange(&DrawTexture{
-			.transform = command.transform.scaled(@floatFromInt(command.resolution orelse .{
+			.size = command.size orelse .{@floatFromInt(texture.width), @floatFromInt(texture.height)},
-				texture.width,
+			.anchor = command.anchor,
-				texture.height,
+			.rotation = command.rotation,
-			})),
+			.depth = command.depth,
+			.source_clip = command.source,
+			.tint = command.tint,
+			.position = command.position,
 		}));
 
 		self.drawn_count += 1;
@@ -178,19 +167,27 @@ const Frame = struct {
 		if (self.current_target_texture) |target_texture| {
 			const texture = resources.get_texture(target_texture).?;
 
-			sokol.gfx.applyUniforms(.VS, 0, sokol.gfx.asRange(&orthographic_projection(-1.0, 1.0, .{
+			sokol.gfx.applyUniforms(.VS, 0, sokol.gfx.asRange(&View{
+				.projection_matrix = orthographic_projection(-1.0, 1.0, .{
 					.left = 0,
 					.top = 0,
 					.right = @floatFromInt(texture.width),
 					.bottom = @floatFromInt(texture.height),
-			})));
+				}),
+
+				.transform_matrix = self.transform_matrix,
+			}));
 		} else {
-			sokol.gfx.applyUniforms(.VS, 0, sokol.gfx.asRange(&orthographic_projection(-1.0, 1.0, .{
+			sokol.gfx.applyUniforms(.VS, 0, sokol.gfx.asRange(&View{
+				.projection_matrix = orthographic_projection(-1.0, 1.0, .{
 					.left = 0,
 					.top = 0,
 					.right = @floatFromInt(self.width),
 					.bottom = @floatFromInt(self.height),
-			})));
+				}),
+
+				.transform_matrix = self.transform_matrix,
+			}));
 		}
 
 		if (effect.properties.len != 0) {
@@ -215,7 +212,7 @@ const Frame = struct {
 		}
 	}
 
-	pub fn set_effect(self: *Frame, resources: *Resources, command: gfx.Commands.SetEffectCommand) void {
+	pub fn set_effect(self: *Frame, resources: *Resources, command: gfx.Command.SetEffect) void {
 		if (command.effect != self.current_effect) {
 			self.flush(resources);
 		}
@@ -227,7 +224,7 @@ const Frame = struct {
 		}
 	}
 
-	pub fn set_target(self: *Frame, resources: *Resources, command: gfx.Commands.SetTargetCommand) void {
+	pub fn set_target(self: *Frame, resources: *Resources, command: gfx.Command.SetTarget) void {
 		sokol.gfx.endPass();
 
 		var pass = sokol.gfx.Pass{
@@ -305,18 +302,23 @@ const Frame = struct {
 	}
 };
 
-fn Matrix(comptime n: usize, comptime Element: type) type {
+const Matrix = [4]@Vector(4, f32);
-	return [n]@Vector(n, Element);
-}
 
 var default_sampler: sokol.gfx.Sampler = undefined;
 
+const identity_matrix = Matrix{
+	.{1, 0, 0, 0},
+	.{0, 1, 0, 0},
+	.{0, 0, 1, 0},
+	.{0, 0, 0, 1},
+};
+
 const vertex_indices = .{
 	.mesh = 0,
 	.instance = 1,
 };
 
-fn orthographic_projection(near: f32, far: f32, viewport: gfx.Rect) Matrix(4, f32) {
+fn orthographic_projection(near: f32, far: f32, viewport: gfx.Rect) Matrix {
 	const width = viewport.right - viewport.left;
 	const height = viewport.bottom - viewport.top;
 
@@ -397,15 +399,16 @@ pub fn process_work(pending_work: *gfx.Assets.WorkQueue, window: *ext.SDL_Window
 				}
 			},
 
-			.render_frame => |render_frame| {
+			.render_frame => |*render_frame| {
 				frame.start(render_frame.width, render_frame.height);
 
-				var has_command_params = render_frame.has_command_params;
+				inline for (&render_frame.commands_set) |has_commands| {
+					var has_commands_currently = has_commands;
 
-				while (has_command_params) |command_params| : (has_command_params = command_params.has_next) {
+					while (has_commands_currently) |commands| : (has_commands_currently = commands.has_next) {
-					for (command_params.param.submitted_commands()) |command| {
+						for (commands.param.submitted_commands()) |command| {
 							try switch (command) {
-							.draw_rect => |draw_rect| frame.draw_rect(&resources, draw_rect),
+								.draw_font => |draw_font| frame.draw_font(&resources, draw_font),
 								.draw_texture => |draw_texture| frame.draw_texture(&resources, draw_texture),
 								.set_effect => |set_effect| frame.set_effect(&resources, set_effect),
 								.set_target => |set_target| frame.set_target(&resources, set_target),
@@ -422,6 +425,7 @@ pub fn process_work(pending_work: *gfx.Assets.WorkQueue, window: *ext.SDL_Window
 							});
 						}
 					}
+				}
 
 				frame.finish(&resources);
 				ext.SDL_GL_SwapWindow(window);

src/gfx/shaders/2d_default.vert

@@ -1,29 +0,0 @@
-#version 430
-
-layout (location = 0) in vec2 mesh_xy;
-layout (location = 1) in vec2 mesh_uv;
-
-layout (location = 2) in vec2 instance_xbasis;
-layout (location = 3) in vec2 instance_ybasis;
-layout (location = 4) in vec2 instance_origin;
-layout (location = 5) in vec4 instance_tint;
-layout (location = 6) in float instance_depth;
-layout (location = 7) in vec4 instance_clip;
-
-layout (location = 0) out vec4 color;
-layout (location = 1) out vec2 uv;
-
-layout (binding = 0) uniform View {
-	mat4 projection_matrix;
-};
-
-void main() {
-	const vec2 world_position = instance_origin + mesh_xy.x * instance_xbasis + mesh_xy.y * instance_ybasis;
-	const vec2 projected_position = (projection_matrix * vec4(world_position, 0, 1)).xy;
-	const vec2 rect_size = instance_clip.zw - instance_clip.xy;
-	const vec4 screen_position = vec4(projected_position, instance_depth, 1.0);
-
-	gl_Position = screen_position;
-	color = instance_tint;
-	uv = instance_clip.xy + (mesh_uv * rect_size);
-}

src/gfx/shaders/draw_texture.vert

@@ -0,0 +1,42 @@
+#version 430
+
+layout (location = 0) in vec2 batch_xy;
+layout (location = 1) in vec2 batch_uv;
+
+layout (location = 2) in float instance_rotation;
+layout (location = 3) in float instance_depth;
+layout (location = 4) in vec2 instance_position;
+layout (location = 5) in vec2 instance_scale;
+layout (location = 6) in vec2 instance_anchor;
+layout (location = 7) in vec4 instance_clip;
+layout (location = 8) in vec4 instance_tint;
+
+layout (location = 0) out vec4 color;
+layout (location = 1) out vec2 uv;
+
+layout (binding = 0) uniform View {
+	mat4 projection_matrix;
+	mat4 transform_matrix;
+};
+
+void main() {
+	const vec2 normalized_position = (batch_xy + 0.5) - instance_anchor;
+	const float cos_theta = cos(instance_rotation);
+	const float sin_theta = sin(instance_rotation);
+
+	const mat2 rotation_matrix = mat2(
+		cos_theta, -sin_theta,
+		sin_theta,  cos_theta
+	);
+
+	const vec2 rotated_position = rotation_matrix * (normalized_position * instance_scale);
+	const vec2 world_position = instance_position + rotated_position;
+	const vec4 clip_space_position = projection_matrix * transform_matrix * vec4(world_position, 0.0, 1.0);
+
+	gl_Position = vec4(clip_space_position.xy, instance_depth, 1.0);
+
+	const vec2 clip_size = instance_clip.zw - instance_clip.xy;
+
+	uv = instance_clip.xy + (batch_uv * clip_size);
+	color = instance_tint;
+}

src/gfx/spirv.zig

@@ -232,9 +232,7 @@ pub const Stage = struct {
 						else => error.UnsupportedSPIRV,
 					},
 
-					.len = std.math.cast(u16, ext.spvc_type_get_array_dimension(member_type_handle, 0)) orelse {
+					.len = std.math.cast(u16, ext.spvc_type_get_array_dimension(member_type_handle, 0)) orelse 0,
-						return error.UnsupportedSPIRV;
-					},
 				};
 			}
 

src/gui/gui.zig

@@ -0,0 +1,234 @@
+const gfx = @import("gfx");
+
+const ona = @import("ona");
+
+const std = @import("std");
+
+pub const Box = struct {
+	left: f32,
+	top: f32,
+	width: f32,
+	height: f32,
+};
+
+pub const Canvas = struct {
+	nodes: ona.stack.Parallel(Node) = .{},
+	drawable_blocks: ona.stack.Sequential(DrawableBlock) = .{},
+	drawable_labels: ona.stack.Sequential(DrawableLabel) = .{},
+
+	fn Drawable(comptime State: type) type {
+		return struct {
+			state: State,
+			depth: f32,
+		};
+	}
+
+	const DrawableBlock = Drawable(struct {
+		background: gfx.Texture = .default,
+		color: gfx.Color = gfx.colors.white,
+	});
+
+	const DrawableLabel = Drawable(struct {
+		text: ona.stack.Sequential(u8) = .{},
+		color: gfx.Color = gfx.colors.black,
+		font: gfx.Font = .default,
+	});
+
+	const Node = struct {
+		name: []u8,
+		box: Box,
+		parent_index: u32 = unused_index,
+		block_index: u32 = unused_index,
+		label_index: u32 = unused_index,
+		style_index: u32 = unused_index,
+
+		const unused_index = std.math.maxInt(u32);
+	};
+
+	pub fn append(self: *Canvas, name: []const u8, box: Box) std.mem.Allocator.Error!Item {
+		const duped_name = try ona.heap.allocator.dupe(u8, name);
+
+		errdefer {
+			ona.heap.allocator.free(duped_name);
+		}
+
+		const index = self.nodes.len();
+
+		try self.nodes.push_grow(.{
+			.name = duped_name,
+			.box = box,
+		});
+
+		errdefer {
+			std.debug.assert(self.nodes.pop());
+		}
+
+		const node_count = self.nodes.len();
+
+		try self.drawable_blocks.grow(ona.scalars.sub(node_count, self.drawable_blocks.cap) orelse 0);
+		try self.drawable_labels.grow(ona.scalars.sub(node_count, self.drawable_labels.cap) orelse 0);
+
+		return @enumFromInt(index);
+	}
+
+	fn calculate_depth(self: Canvas, item: Item) f32 {
+		const parent_indices = self.nodes.values.slice(.parent_index);
+		var depth: f32 = 0;
+		var index = @intFromEnum(item);
+
+		while (true) : (depth += 1) {
+			const parent_index = parent_indices[index];
+
+			if (parent_index == Node.unused_index) {
+				break;
+			}
+
+			index = parent_index;
+		}
+
+		return depth;
+	}
+
+	fn deinit(self: *Canvas) void {
+		self.nodes.deinit();
+		self.drawable_blocks.deinit();
+
+		for (self.drawable_labels.values) |*drawable_label| {
+			drawable_label.state.text.deinit();
+		}
+
+		self.drawable_labels.deinit();
+
+		self.* = undefined;
+	}
+
+	const label_depth_offset = 0.5;
+
+	pub fn set_block(self: *Canvas, item: Item, set: SetBlock) void {
+		const block_index = self.nodes.values.get(.block_index, @intFromEnum(item)).?;
+
+		if (block_index.* == Node.unused_index) {
+			block_index.* = @intCast(self.drawable_blocks.len());
+
+			std.debug.assert(self.drawable_blocks.push(.{
+				.depth = self.calculate_depth(item),
+				.state = .{},
+			}));
+		}
+
+		const block = &self.drawable_blocks.values[block_index.*];
+
+		if (set.has_background) |background| {
+			block.state.background = background;
+		}
+
+		if (set.has_color) |color| {
+			block.state.color = color;
+		}
+	}
+
+	pub fn set_label(self: *Canvas, item: Item, set: SetLabel) std.mem.Allocator.Error!void {
+		const label_index = self.nodes.values.get(.label_index, @intFromEnum(item)).?;
+
+		if (label_index.* == Node.unused_index) {
+			label_index.* = @intCast(self.drawable_labels.len());
+
+			std.debug.assert(self.drawable_labels.push(.{
+				.depth = self.calculate_depth(item) + label_depth_offset,
+				.state = .{},
+			}));
+		}
+
+		const label = &self.drawable_labels.values[label_index.*];
+
+		if (set.has_text) |text| {
+			label.state.text.pop_all();
+
+			try label.state.text.grow(ona.scalars.sub(text.len, label.state.text.cap) orelse 0);
+
+			std.debug.assert(label.state.text.push_all(text));
+		}
+
+		if (set.has_font) |font| {
+			label.state.font = font;
+		}
+
+		if (set.has_color) |color| {
+			label.state.color = color;
+		}
+	}
+
+	pub fn set_parent(self: *Canvas, item: Item, has_parent: ?Item) void {
+		const item_index = @intFromEnum(item);
+		const parent_index = self.nodes.values.get(.parent_index, item_index).?;
+
+		parent_index.* = if (has_parent) |parent| @intFromEnum(parent) else Node.unused_index;
+
+		const label_index = self.nodes.values.get(.parent_index, item_index).?.*;
+		const block_index = self.nodes.values.get(.parent_index, item_index).?.*;
+		const label_index_exists = label_index != Node.unused_index;
+		const block_index_exists = block_index != Node.unused_index;
+
+		if (label_index_exists or block_index_exists) {
+			const depth = self.calculate_depth(item);
+
+			if (label_index_exists) {
+				self.drawable_labels[label_index].depth = depth + label_depth_offset;
+			}
+
+			if (block_index_exists) {
+				self.drawable_labels[label_index].depth = depth;
+			}
+		}
+	}
+};
+
+pub const Item = enum (u32) {
+	_,
+};
+
+pub const SetBlock = struct {
+	has_background: ?gfx.Texture = null,
+	has_color: ?gfx.Color = null,
+};
+
+pub const SetLabel = struct {
+	has_text: ?[]const u8 = null,
+	has_color: ?gfx.Color = null,
+	has_font: ?gfx.Font = null,
+};
+
+pub fn exit(canvas: ona.Write(Canvas)) !void {
+	canvas.state.deinit();
+}
+
+pub fn render(commands: gfx.Commands(.overlay), canvas: ona.Read(Canvas)) !void {
+	const boxes = canvas.state.nodes.values.slice(.box);
+
+	for (canvas.state.drawable_blocks.values, boxes) |block, box| {
+		try commands.draw_texture(.{
+			.depth = block.depth,
+			.position = .{box.left, box.top},
+			.size = .{box.width, box.height},
+			.texture = block.state.background,
+			.tint = block.state.color,
+		});
+	}
+
+	for (canvas.state.drawable_labels.values, boxes) |label, box| {
+		try commands.draw_font(.{
+			.depth = label.depth,
+			.text = label.state.text.values,
+			.position = .{box.left, box.top},
+			.size = .{box.width, box.height},
+			.tint = label.state.color,
+			.font = label.state.font,
+		});
+	}
+}
+
+pub fn setup(world: *ona.World) !void {
+	try world.set_state(Canvas{});
+	try world.on_event(.render, ona.system_fn(render), .{.label = "render gui"});
+	try world.on_event(.exit, ona.system_fn(exit), .{.label = "cleanup gui"});
+}

src/hid/hid.zig

@@ -293,10 +293,10 @@ test "mapping values" {
 	}
 }
 
-pub fn setup(world: *ona.World, events: ona.App.Events) std.mem.Allocator.Error!void {
+pub fn setup(world: *ona.World) std.mem.Allocator.Error!void {
 	try world.set_state(Mapping{});
 
-	try world.on_event(events.pre_update, ona.system_fn(update), .{
+	try world.on_event(.pre_update, ona.system_fn(update), .{
 		.label = "update actions",
 	});
 }

src/ona/World.zig

@@ -6,7 +6,7 @@ const std = @import("std");
 
 thread_pool: ?*std.Thread.Pool = null,
 thread_restricted_resources: [std.enums.values(ona.ThreadRestriction).len]StateTable,
-event_systems: ona.stack.Sequential(Schedule),
+event_schedules: ona.map.Hashed([]const u8, *Schedule, ona.map.string_traits),
 
 pub const BindContext = struct {
 	node: ona.dag.Node,
@@ -110,8 +110,6 @@ const Graph = ona.dag.Graph(struct {
 	resource_accesses: ona.stack.Sequential(StateAccess),
 });
 
-pub const Event = enum (usize) { _ };
-
 const ParallelNodeBundles = ona.stack.Sequential(NodeBundle);
 
 const NodeBundle = ona.stack.Sequential(ona.dag.Node);
@@ -442,22 +440,16 @@ const Schedule = struct {
 		}
 	}
 
-	pub fn init(label: []const u8) std.mem.Allocator.Error!Schedule {
+	pub fn init(comptime label: [:0]const u8) std.mem.Allocator.Error!Schedule {
-		var arena = std.heap.ArenaAllocator.init(ona.heap.allocator);
-
-		errdefer arena.deinit();
-
-		const duped_label = try arena.allocator().dupeZ(u8, label);
-
 		return .{
 			.graph = Graph.init(ona.heap.allocator),
-			.label = duped_label,
+			.arena = std.heap.ArenaAllocator.init(ona.heap.allocator),
-			.arena = arena,
+			.label = label,
-			.system_id_nodes = .{.allocator = ona.heap.allocator},
+			.system_id_nodes = .{},
-			.read_write_resource_id_nodes = .{.allocator = ona.heap.allocator},
+			.read_write_resource_id_nodes = .{},
-			.read_only_resource_id_nodes = .{.allocator = ona.heap.allocator},
+			.read_only_resource_id_nodes = .{},
-			.parallel_work_bundles = .{.allocator = ona.heap.allocator},
+			.parallel_work_bundles = .{},
-			.blocking_work = .{.allocator = ona.heap.allocator},
+			.blocking_work = .{},
 		};
 	}
 
@@ -544,21 +536,12 @@ pub const UnbindContext = struct {
 	world: *Self,
 };
 
-pub fn create_event(self: *Self, label: []const u8) std.mem.Allocator.Error!Event {
-	var systems = try Schedule.init(label);
-
-	errdefer systems.deinit(self);
-
-	const index = self.event_systems.len();
-
-	try self.event_systems.push_grow(systems);
-
-	return @enumFromInt(index);
-}
-
 pub fn deinit(self: *Self) void {
-	for (self.event_systems.values) |*schedule| {
+	var event_schedules = self.event_schedules.entries();
-		schedule.deinit(self);
+
+	while (event_schedules.next()) |schedule| {
+		schedule.value.deinit(self);
+		ona.heap.allocator.destroy(schedule.value);
 	}
 
 	for (&self.thread_restricted_resources) |*resources| {
@@ -570,7 +553,7 @@ pub fn deinit(self: *Self) void {
 		ona.heap.allocator.destroy(thread_pool);
 	}
 
-	self.event_systems.deinit();
+	self.event_schedules.deinit();
 
 	self.* = undefined;
 }
@@ -594,7 +577,7 @@ pub fn set_get_state(self: *Self, value: anytype) std.mem.Allocator.Error!*@Type
 pub fn init(thread_count: u32) std.Thread.SpawnError!Self {
 	var world = Self{
 		.thread_restricted_resources = .{StateTable.init(), StateTable.init()},
-		.event_systems = .{.allocator = ona.heap.allocator},
+		.event_schedules = .{.allocator = ona.heap.allocator},
 	};
 
 	if (thread_count != 0 and !builtin.single_threaded) {
@@ -611,12 +594,34 @@ pub fn init(thread_count: u32) std.Thread.SpawnError!Self {
 	return world;
 }
 
-pub fn on_event(self: *Self, event: Event, action: *const ona.SystemInfo, order: ona.SystemOrder) std.mem.Allocator.Error!void {
+pub fn on_event(self: *Self, comptime event: anytype, info: *const ona.SystemInfo, order: ona.SystemOrder) std.mem.Allocator.Error!void {
-	try self.event_systems.values[@intFromEnum(event)].insert(action, order);
+	const event_name = @tagName(event);
+
+	if (self.event_schedules.get(event_name)) |schedule| {
+		try schedule.*.insert(info, order);
+	} else {
+		const schedule = try ona.heap.allocator.create(Schedule);
+
+		errdefer {
+			ona.heap.allocator.destroy(schedule);
 		}
 
-pub fn run_event(self: *Self, event: Event) anyerror!void {
+		schedule.* = try Schedule.init(event_name);
-	try self.event_systems.values[@intFromEnum(event)].run(self);
+
+		errdefer {
+			schedule.deinit(self);
+		}
+
+		try schedule.insert(info, order);
+
+		std.debug.assert(try self.event_schedules.emplace(event_name, schedule));
+	}
+}
+
+pub fn run_event(self: *Self, comptime event: anytype) anyerror!void {
+	if (self.event_schedules.get(@tagName(event))) |schedule| {
+		try schedule.*.run(self);
+	}
 }
 
 pub fn set_state(self: *Self, value: anytype) std.mem.Allocator.Error!void {

src/ona/map.zig

@@ -7,7 +7,7 @@ pub fn Hashed(comptime Key: type, comptime Value: type, comptime traits: Traits(
 	const max_int = std.math.maxInt(usize);
 
 	return struct {
-		allocator: std.mem.Allocator,
+		allocator: std.mem.Allocator = ona.heap.allocator,
 		entry_map: []?Entry = &.{},
 		len: usize = 0,
 

src/ona/ona.zig

@@ -29,37 +29,11 @@ pub const World = @import("./World.zig");
 pub const lina = @import("./lina.zig");
 
 pub const App = struct {
-	events: *const Events,
+	step: fn (*World) anyerror!void = noop,
-	target_frame_time: f64,
-	elapsed_time: f64,
-	is_running: bool,
 
-	pub const Events = struct {
+	fn noop(_: *World) !void {}
-		load: World.Event,
-		pre_update: World.Event,
-		update: World.Event,
-		post_update: World.Event,
-		render: World.Event,
-		finish: World.Event,
-		exit: World.Event,
-	};
 
-	pub const Setup = struct {
+	pub fn build(self: App) fn () anyerror!void {
-		pub const Event = enum {
-			load,
-			pre_update,
-			update,
-			post_update,
-			render,
-			finish,
-			exit,
-		};
-
-		step: fn (*World, Events) anyerror!void = noop,
-
-		fn noop(_: *World, _: Events) !void {}
-
-		pub fn build(self: Setup) fn () anyerror!void {
 		const Start = struct {
 			fn main() anyerror!void {
 				defer {
@@ -100,66 +74,60 @@ pub const App = struct {
 
 				defer world.deinit();
 
-					const events = App.Events{
+				try self.step(&world);
-						.load = try world.create_event("load"),
-						.pre_update = try world.create_event("pre-update"),
-						.update = try world.create_event("update"),
-						.post_update = try world.create_event("post-update"),
-						.render = try world.create_event("render"),
-						.finish = try world.create_event("finish"),
-						.exit = try world.create_event("exit"),
-					};
-
-					const app = try world.set_get_state(App{
-						.events = &events,
-						.target_frame_time = 1.0 / 60.0,
-						.elapsed_time = 0,
-						.is_running = true,
-					});
-
-					try self.step(&world, events);
-					try world.run_event(events.load);
-
-					const ticks_initial = std.time.milliTimestamp();
-					var ticks_previous = ticks_initial;
-					var accumulated_time = @as(f64, 0);
-
-					while (app.is_running) {
-						const ticks_current = std.time.milliTimestamp();
-						const milliseconds_per_second = 1000.0;
-						const delta_time = @as(f64, @floatFromInt(ticks_current - ticks_previous)) / milliseconds_per_second;
-
-						app.elapsed_time = @as(f64, @floatFromInt(ticks_current - ticks_initial)) / milliseconds_per_second;
-						ticks_previous = ticks_current;
-						accumulated_time += delta_time;
-
-						try world.run_event(events.pre_update);
-
-						while (accumulated_time >= app.target_frame_time) : (accumulated_time -= app.target_frame_time) {
-							try world.run_event(events.update);
-						}
-
-						try world.run_event(events.post_update);
-						try world.run_event(events.render);
-						try world.run_event(events.finish);
-					}
-
-					try world.run_event(events.exit);
 			}
 		};
 
 		return Start.main;
 	}
 
-		pub fn with_module(self: Setup, comptime Module: type) Setup {
+	pub const game = App{.step = run_game};
+
+	fn run_game(world: *World) !void {
+		const loop = try world.set_get_state(Loop{
+			.target_frame_time = 1.0 / 60.0,
+			.elapsed_time = 0,
+			.is_running = true,
+		});
+
+		try world.run_event(.load);
+
+		const ticks_initial = std.time.milliTimestamp();
+		var ticks_previous = ticks_initial;
+		var accumulated_time = @as(f64, 0);
+
+		while (loop.is_running) {
+			const ticks_current = std.time.milliTimestamp();
+			const milliseconds_per_second = 1000.0;
+			const delta_time = @as(f64, @floatFromInt(ticks_current - ticks_previous)) / milliseconds_per_second;
+
+			loop.elapsed_time = @as(f64, @floatFromInt(ticks_current - ticks_initial)) / milliseconds_per_second;
+			ticks_previous = ticks_current;
+			accumulated_time += delta_time;
+
+			try world.run_event(.pre_update);
+
+			while (accumulated_time >= loop.target_frame_time) : (accumulated_time -= loop.target_frame_time) {
+				try world.run_event(.update);
+			}
+
+			try world.run_event(.post_update);
+			try world.run_event(.render);
+			try world.run_event(.finish);
+		}
+
+		try world.run_event(.exit);
+	}
+
+	pub fn with_module(self: App, comptime Module: type) App {
 		if (!@hasDecl(Module, "setup")) {
 			@compileError("`Module` argument must have a setup fn declaration");
 		}
 
 		const WithState = struct {
-				fn step(world: *World, events: App.Events) !void {
+			fn step(world: *World) !void {
-					try Module.setup(world, events);
+				try Module.setup(world);
-					try self.step(world, events);
+				try self.step(world);
 			}
 		};
 
@@ -168,11 +136,11 @@ pub const App = struct {
 		};
 	}
 
-		pub fn with_state(self: Setup, comptime state: anytype) Setup {
+	pub fn with_state(self: App, comptime state: anytype) App {
 		const WithState = struct {
-				fn step(world: *World, events: App.Events) !void {
+			fn step(world: *World) !void {
 				try world.set_state(state);
-					try self.step(world, events);
+				try self.step(world);
 			}
 		};
 
@@ -181,21 +149,11 @@ pub const App = struct {
 		};
 	}
 
-		pub fn with_system(self: Setup, comptime event: Event, comptime info: *const SystemInfo, comptime order: SystemOrder) Setup {
+	pub fn with_system(self: App, comptime event: anytype, comptime info: *const SystemInfo, comptime order: SystemOrder) App {
 		const WithState = struct {
-				fn step(world: *World, events: App.Events) !void {
+			fn step(world: *World) !void {
-					const app_event = switch (event) {
+				try world.on_event(event, info, order);
-						.load => events.load,
+				try self.step(world);
-						.pre_update => events.pre_update,
-						.update => events.update,
-						.post_update => events.post_update,
-						.render => events.render,
-						.finish => events.finish,
-						.exit => events.exit,
-					};
-
-					try world.on_event(app_event, info, order);
-					try self.step(world, events);
 			}
 		};
 
@@ -205,9 +163,12 @@ pub const App = struct {
 	}
 };
 
-	pub const setup = Setup{};
+pub const Loop = struct {
+	target_frame_time: f64,
+	elapsed_time: f64,
+	is_running: bool,
 
-	pub fn quit(self: *App) void {
+	pub fn quit(self: *Loop) void {
 		self.is_running = false;
 	}
 };
@@ -355,7 +316,10 @@ pub const LaunchFlag = enum {
 
 pub fn Params(comptime Value: type) type {
 	if (!@hasDecl(Value, "Param")) {
-		@compileError("System parameters must have a Params type declaration");
+		@compileError(@typeName(Value) ++
+			\\ is missing a public `Params` type declaration.
+			\\This is required for a type to be used as a system parameter
+			);
 	}
 
 	return struct {
@@ -519,15 +483,11 @@ pub fn Receive(comptime Message: type) type {
 				.channel = (try context.register_readable_state_access(TypedChannel)) orelse set: {
 					try context.world.set_state(TypedChannel.init(heap.allocator));
 
-					const app = context.world.get_state(App) orelse {
+					try context.world.on_event(.post_update, system_fn(TypedChannel.swap), .{
-						@panic("Send system parameters depend on a " ++ @typeName(App) ++ " state to work");
-					};
-
-					try context.world.on_event(app.events.post_update, system_fn(TypedChannel.swap), .{
 						.label = "swap channel of " ++ @typeName(Message),
 					});
 
-					try context.world.on_event(app.events.exit, system_fn(TypedChannel.cleanup), .{
+					try context.world.on_event(.exit, system_fn(TypedChannel.cleanup), .{
 						.label = "clean up channel of " ++ @typeName(Message),
 					});
 
@@ -565,15 +525,11 @@ pub fn Send(comptime Message: type) type {
 				.channel = (try context.register_writable_state_access(TypedChannel)) orelse set: {
 					try context.world.set_state(TypedChannel.init(heap.allocator));
 
-					const app = context.world.get_state(App) orelse {
+					try context.world.on_event(.post_update, system_fn(TypedChannel.swap), .{
-						@panic("Send system parameters depend on a " ++ @typeName(App) ++ " state to work");
-					};
-
-					try context.world.on_event(app.events.post_update, system_fn(TypedChannel.swap), .{
 						.label = "swap channel of " ++ @typeName(Message),
 					});
 
-					try context.world.on_event(app.events.exit, system_fn(TypedChannel.cleanup), .{
+					try context.world.on_event(.exit, system_fn(TypedChannel.cleanup), .{
 						.label = "clean up channel of " ++ @typeName(Message),
 					});
 

src/ona/stack.zig

@@ -69,6 +69,10 @@ pub fn Sequential(comptime Value: type) type {
 			return true;
 		}
 
+		pub fn pop_all(self: *Self) void {
+			self.values = self.values[0 .. 0];
+		}
+
 		pub fn pop_many(self: *Self, n: usize) bool {
 			const new_length = ona.scalars.sub(self.values.len, n) orelse {
 				return false;
@@ -247,6 +251,16 @@ pub fn Parallel(comptime Value: type) type {
 			return self.values.len;
 		}
 
+		pub fn pop(self: *Self) bool {
+			if (self.values.len == 0) {
+				return false;
+			}
+
+			self.values = self.values.slice_all(0, self.values.len - 1).?;
+
+			return true;
+		}
+
 		pub fn pop_many(self: *Self, n: usize) bool {
 			const new_length = ona.scalars.sub(self.values.len, n) orelse {
 				return false;