Update to Zig 0.13.0

.gitignore

@@ -1,4 +1,4 @@
 # Generated assets
-/zig-cache
+/.zig-cache
 /zig-out
 *.glsl.zig

build.zig.zon

@@ -10,8 +10,8 @@
     },
     .dependencies = .{
         .sokol = .{
-            .url = "git+https://github.com/floooh/sokol-zig.git#796a3d3d54c22d20da9e91a9a9120d5423d1e700",
-            .hash = "12209a187e071d76af00c02865677d170f844376866d062b1b5f82e4ecbd750c4e18",
+            .url = "git+https://github.com/floooh/sokol-zig.git#7c25767e51aa06dd5fb0684e4a8f2200d182ef27",
+			.hash = "1220fa7f47fbaf2f1ed8c17fab2d23b6a85bcbbc4aa0b3802c90a3e8bf6fca1f8569",
         },
     },
 }

src/coral/World.zig

@@ -32,7 +32,7 @@ pub fn create_event(self: *Self, label: []const u8) std.mem.Allocator.Error!Even
 
 	const index = self.event_systems.len();
 
-	try self.event_systems.push(systems);
+	try self.event_systems.push_grow(systems);
 
 	return @enumFromInt(index);
 }

src/coral/coral.zig

@@ -2,7 +2,7 @@ pub const ascii = @import("./ascii.zig");
 
 pub const dag = @import("./dag.zig");
 
-pub const debug = @import("./debug.zig");
+pub const files = @import("./files.zig");
 
 pub const hashes = @import("./hashes.zig");
 

src/coral/dag.zig

@@ -21,7 +21,7 @@ pub fn Graph(comptime Payload: type) type {
 		pub fn append(self: *Self, payload: Payload) std.mem.Allocator.Error!Node {
 			const node = @as(Node, @enumFromInt(self.table.len()));
 
-			try self.table.push(.{
+			try self.table.push_grow(.{
 				.payload = payload,
 				.edges = .{.allocator = self.table.allocator},
 			});
@@ -83,7 +83,7 @@ pub fn Graph(comptime Payload: type) type {
 			};
 
 			if (slices.index_of(edges.values, 0, edge_node) == null) {
-				try edges.push(edge_node);
+				try edges.push_grow(edge_node);
 			}
 
 			return true;

src/coral/debug.zig

@@ -1,5 +0,0 @@
-const std = @import("std");
-
-pub fn assert_ok(error_union: anytype) @typeInfo(@TypeOf(error_union)).ErrorUnion.payload {
-	return error_union catch unreachable;
-}

src/coral/files.zig

@@ -0,0 +1,124 @@
+const builtin = @import("builtin");
+
+const io = @import("./io.zig");
+
+const std = @import("std");
+
+pub const Error = error {
+	FileNotFound,
+	FileInaccessible,
+};
+
+pub const Stat = struct {
+	size: u64,
+};
+
+pub const Storage = struct {
+	userdata: *anyopaque,
+	vtable: *const VTable,
+
+	pub const VTable = struct {
+		stat: *const fn (*anyopaque, []const u8) Error!Stat,
+		read: *const fn (*anyopaque, []const u8, usize, []io.Byte) Error!usize,
+	};
+
+	pub fn read_bytes(self: Storage, path: []const u8, offset: usize, output: []io.Byte) Error!usize {
+		return self.vtable.read(self.userdata, path, offset, output);
+	}
+
+	pub fn read_foreign(self: Storage, path: []const u8, offset: usize, comptime Type: type) Error!?Type {
+		const decoded = (try self.read_native(path, offset, Type)) orelse {
+			return null;
+		};
+
+		return switch (@typeInfo(Type)) {
+			.Struct => std.mem.byteSwapAllFields(Type, &decoded),
+			else => @byteSwap(decoded),
+		};
+	}
+
+	pub fn read_native(self: Storage, path: []const u8, offset: usize, comptime Type: type) Error!?Type {
+		var buffer = @as([@sizeOf(Type)]io.Byte, undefined);
+
+		if (try self.vtable.read(self.userdata, path, offset, &buffer) != buffer.len) {
+			return null;
+		}
+
+		return @as(*align(1) const Type, @ptrCast(&buffer)).*;
+	}
+
+	pub const read_little = switch (native_endian) {
+		.little => read_native,
+		.big => read_foreign,
+	};
+
+	pub const read_big = switch (native_endian) {
+		.little => read_foreign,
+		.big => read_native,
+	};
+};
+
+pub const bundle = init: {
+	const Bundle = struct {
+		fn full_path(path: []const u8) Error![4095:0]u8 {
+			var buffer = [_:0]u8{0} ** 4095;
+
+			_ = std.fs.cwd().realpath(path, &buffer) catch {
+				return error.FileInaccessible;
+			};
+
+			return buffer;
+		}
+
+		fn read(_: *anyopaque, path: []const u8, offset: usize, output: []io.Byte) Error!usize {
+			var file = std.fs.openFileAbsoluteZ(&(try full_path(path)), .{.mode = .read_only}) catch |open_error| {
+				return switch (open_error) {
+					error.FileNotFound => error.FileNotFound,
+					else => error.FileInaccessible,
+				};
+			};
+
+			defer file.close();
+
+			if (offset != 0) {
+				file.seekTo(offset) catch {
+					return error.FileInaccessible;
+				};
+			}
+
+			return file.read(output) catch error.FileInaccessible;
+		}
+
+		fn stat(_: *anyopaque, path: []const u8) Error!Stat {
+			const file_stat = get: {
+				var file = std.fs.openFileAbsoluteZ(&(try full_path(path)), .{.mode = .read_only}) catch |open_error| {
+					return switch (open_error) {
+						error.FileNotFound => error.FileNotFound,
+						else => error.FileInaccessible,
+					};
+				};
+
+				defer file.close();
+
+				break: get file.stat() catch {
+					return error.FileInaccessible;
+				};
+			};
+
+			return .{
+				.size = file_stat.size,
+			};
+		}
+	};
+
+	break: init Storage{
+		.userdata = undefined,
+
+		.vtable = &.{
+			.stat = Bundle.stat,
+			.read = Bundle.read,
+		},
+	};
+};
+
+const native_endian = builtin.cpu.arch.endian();

src/coral/io.zig

@@ -6,23 +6,30 @@ const slices = @import("./slices.zig");
 
 const std = @import("std");
 
-pub const Byte = u8;
+pub const Writable = struct {
+	data: []Byte,
 
-pub const Decoder = coral.io.Functor(coral.io.Error!void, &.{[]coral.Byte});
+	pub fn writer(self: *Writable) Writer {
+		return Writer.bind(Writable, self, write);
+	}
+
+	fn write(self: *Writable, buffer: []const u8) !usize {
+		const range = @min(buffer.len, self.data.len);
+
+		@memcpy(self.data[0 .. range], buffer[0 .. range]);
+
+		self.data = self.data[range ..];
+
+		return buffer.len;
+	}
+};
+
+pub const Byte = u8;
 
 pub const Error = error {
 	UnavailableResource,
 };
 
-pub fn FixedBuffer(comptime len: usize, comptime default_value: anytype) type {
-	const Value = @TypeOf(default_value);
-
-	return struct {
-		filled: usize = 0,
-		values: [len]Value = [_]Value{default_value} ** len,
-	};
-}
-
 pub fn Functor(comptime Output: type, comptime input_types: []const type) type {
 	const InputTuple = std.meta.Tuple(input_types);
 
@@ -119,20 +126,6 @@ pub fn Generator(comptime Output: type, comptime input_types: []const type) type
 	};
 }
 
-pub const NullWritable = struct {
-	written: usize = 0,
-
-	pub fn writer(self: *NullWritable) Writer {
-		return Writer.bind(NullWritable, self, write);
-	}
-
-	pub fn write(self: *NullWritable, buffer: []const u8) !usize {
-		self.written += buffer.len;
-
-		return buffer.len;
-	}
-};
-
 pub const PrintError = Error || error {
 	IncompleteWrite,
 };
@@ -141,8 +134,6 @@ pub const Reader = Generator(Error!usize, &.{[]coral.Byte});
 
 pub const Writer = Generator(Error!usize, &.{[]const coral.Byte});
 
-const native_endian = builtin.cpu.arch.endian();
-
 pub fn alloc_read(input: coral.io.Reader, allocator: std.mem.Allocator) []coral.Byte {
 	const buffer = coral.Stack(coral.Byte){.allocator = allocator};
 
@@ -153,20 +144,6 @@ pub fn alloc_read(input: coral.io.Reader, allocator: std.mem.Allocator) []coral.
 	return buffer.to_allocation(streamed);
 }
 
-pub fn are_equal(a: []const Byte, b: []const Byte) bool {
-	if (a.len != b.len) {
-		return false;
-	}
-
-	for (0 .. a.len) |i| {
-		if (a[i] != b[i]) {
-			return false;
-		}
-	}
-
-	return true;
-}
-
 pub const bits_per_byte = 8;
 
 pub fn bytes_of(value: anytype) []const Byte {
@@ -179,14 +156,6 @@ pub fn bytes_of(value: anytype) []const Byte {
 	};
 }
 
-pub fn ends_with(haystack: []const Byte, needle: []const Byte) bool {
-	if (needle.len > haystack.len) {
-		return false;
-	}
-
-	return are_equal(haystack[haystack.len - needle.len ..], needle);
-}
-
 pub fn print(writer: Writer, utf8: []const u8) PrintError!void {
 	if (try writer.yield(.{utf8}) != utf8.len) {
 		return error.IncompleteWrite;
@@ -208,35 +177,6 @@ pub fn skip_n(input: Reader, distance: u64) Error!void {
 	}
 }
 
-pub fn read_foreign(input: Reader, comptime Type: type) Error!Type {
-	const decoded = try read_native(input, Type);
-
-	return switch (@typeInfo(input)) {
-		.Struct => std.mem.byteSwapAllFields(Type, &decoded),
-		else => @byteSwap(decoded),
-	};
-}
-
-pub fn read_native(input: Reader, comptime Type: type) Error!Type {
-	var buffer = @as([@sizeOf(Type)]coral.Byte, undefined);
-
-	if (try input.yield(.{&buffer}) != buffer.len) {
-		return error.UnavailableResource;
-	}
-
-	return @as(*align(1) const Type, @ptrCast(&buffer)).*;
-}
-
-pub const read_little = switch (native_endian) {
-	.little => read_native,
-	.big => read_foreign,
-};
-
-pub const read_big = switch (native_endian) {
-	.little => read_foreign,
-	.big => read_native,
-};
-
 pub fn slice_sentineled(comptime sen: anytype, ptr: [*:sen]const @TypeOf(sen)) [:sen]const @TypeOf(sen) {
 	var len = @as(usize, 0);
 

src/coral/resource.zig

@@ -53,7 +53,7 @@ pub const Table = struct {
 			errdefer resource_allocator.destroy(allocated_resource);
 
 			std.debug.assert(try self.table.emplace(value_id, .{
-				.ptr = allocated_resource,
+				.ptr = @ptrCast(allocated_resource),
 			}));
 
 			allocated_resource.* = value;

src/coral/stack.zig

@@ -29,6 +29,10 @@ pub fn Sequential(comptime Value: type) type {
 		}
 
 		pub fn grow(self: *Self, additional: usize) std.mem.Allocator.Error!void {
+			if (additional == 0) {
+				return;
+			}
+
 			const grown_capacity = self.cap + additional;
 			const buffer = try self.allocator.alloc(Value, grown_capacity);
 
@@ -87,7 +91,39 @@ pub fn Sequential(comptime Value: type) type {
 			return true;
 		}
 
-		pub fn push(self: *Self, value: Value) std.mem.Allocator.Error!void {
+		pub fn push(self: *Self, value: Value) bool {
+			if (self.values.len == self.cap) {
+				return false;
+			}
+
+			const offset_index = self.values.len;
+
+			self.values = self.values.ptr[0 .. self.values.len + 1];
+
+			self.values[offset_index] = value;
+
+			return true;
+		}
+
+		pub fn push_all(self: *Self, values: []const Value) bool {
+			const new_length = self.values.len + values.len;
+
+			if (new_length > self.cap) {
+				return false;
+			}
+
+			const offset_index = self.values.len;
+
+			self.values = self.values.ptr[0 .. new_length];
+
+			for (0 .. values.len) |index| {
+				self.values[offset_index + index] = values[index];
+			}
+
+			return true;
+		}
+
+		pub fn push_grow(self: *Self, value: Value) std.mem.Allocator.Error!void {
 			if (self.values.len == self.cap) {
 				try self.grow(@max(1, self.cap));
 			}
@@ -99,27 +135,11 @@ pub fn Sequential(comptime Value: type) type {
 			self.values[offset_index] = value;
 		}
 
-		pub fn push_all(self: *Self, values: []const Value) std.mem.Allocator.Error!void {
-			const new_length = self.values.len + values.len;
-
-			if (new_length > self.cap) {
-				try self.grow(new_length);
-			}
-
-			const offset_index = self.values.len;
-
-			self.values = self.values.ptr[0 .. new_length];
-
-			for (0 .. values.len) |index| {
-				self.values[offset_index + index] = values[index];
-			}
-		}
-
 		pub fn push_many(self: *Self, n: usize, value: Value) std.mem.Allocator.Error!void {
 			const new_length = self.values.len + n;
 
 			if (new_length > self.cap) {
-				try self.grow(new_length);
+				return false;
 			}
 
 			const offset_index = self.values.len;
@@ -129,6 +149,8 @@ pub fn Sequential(comptime Value: type) type {
 			for (0 .. n) |index| {
 				self.values[offset_index + index] = value;
 			}
+
+			return true;
 		}
 
 		pub fn resize(self: *Self, size: usize, default_value: Value) std.mem.Allocator.Error!void {
@@ -237,7 +259,7 @@ pub fn Parallel(comptime Value: type) type {
 			return self.values.len;
 		}
 
-		pub fn push(self: *Self, value: Value) std.mem.Allocator.Error!void {
+		pub fn push_grow(self: *Self, value: Value) std.mem.Allocator.Error!void {
 			if (self.len() == self.cap) {
 				try self.grow(@max(1, self.cap));
 			}

src/coral/system.zig

@@ -51,7 +51,7 @@ pub const BindContext = struct {
 		const id = resource.type_id(Resource);
 
 		if (!self.accesses_resource(.read_write, id)) {
-			try self.systems.graph.get_ptr(self.node).?.resource_accesses.push(.{.read_write = id});
+			try self.systems.graph.get_ptr(self.node).?.resource_accesses.push_grow(.{.read_write = id});
 		}
 
 		const read_write_resource_nodes = lazily_create: {
@@ -65,7 +65,7 @@ pub const BindContext = struct {
 		};
 
 		if (slices.index_of(read_write_resource_nodes.values, 0, self.node) == null) {
-			try read_write_resource_nodes.push(self.node);
+			try read_write_resource_nodes.push_grow(self.node);
 		}
 
 		return value;
@@ -79,7 +79,7 @@ pub const BindContext = struct {
 		const id = resource.type_id(Resource);
 
 		if (!self.accesses_resource(.read_only, id)) {
-			try self.systems.graph.get_ptr(self.node).?.resource_accesses.push(.{.read_only = id});
+			try self.systems.graph.get_ptr(self.node).?.resource_accesses.push_grow(.{.read_only = id});
 		}
 
 		const read_only_resource_nodes = lazily_create: {
@@ -93,7 +93,7 @@ pub const BindContext = struct {
 		};
 
 		if (slices.index_of(read_only_resource_nodes.values, 0, self.node) == null) {
-			try read_only_resource_nodes.push(self.node);
+			try read_only_resource_nodes.push_grow(self.node);
 		}
 
 		return value;
@@ -291,7 +291,7 @@ pub const Schedule = struct {
 						try populate_bundle(bundle, graph, edge);
 					}
 
-					try bundle.push(node);
+					try bundle.push_grow(node);
 				}
 
 				fn sort(schedule: *Schedule) !void {
@@ -304,7 +304,7 @@ pub const Schedule = struct {
 							continue;
 						}
 
-						try schedule.parallel_work_bundles.push(.{.allocator = heap.allocator});
+						try schedule.parallel_work_bundles.push_grow(.{.allocator = heap.allocator});
 
 						const bundle = schedule.parallel_work_bundles.get_ptr().?;
 
@@ -328,8 +328,9 @@ pub const Schedule = struct {
 								.main => {
 									const extracted_work = work.values[index ..];
 
-									try schedule.blocking_work.push_all(extracted_work);
+									try schedule.blocking_work.grow(extracted_work.len);
 
+									std.debug.assert(schedule.blocking_work.push_all(extracted_work));
 									std.debug.assert(work.pop_many(extracted_work.len));
 								},
 							}
@@ -488,7 +489,7 @@ pub const Schedule = struct {
 			});
 		}
 
-		try nodes.push(node);
+		try nodes.push_grow(node);
 
 		self.invalidate_work();
 	}

src/coral/utf8.zig

@@ -2,8 +2,6 @@ const ascii = @import("./ascii.zig");
 
 const coral = @import("./coral.zig");
 
-const debug = @import("./debug.zig");
-
 const io = @import("./io.zig");
 
 const std = @import("std");
@@ -16,7 +14,7 @@ pub fn alloc_formatted(allocator: std.mem.Allocator, comptime format: []const u8
 
 	errdefer buffer.deinit();
 
-	debug.assert_try(print_formatted(buffer.writer(), format, args));
+	print_formatted(buffer.writer(), format, args) catch unreachable;
 
 	return buffer.to_allocation(formatted_len, 0);
 }
@@ -24,7 +22,7 @@ pub fn alloc_formatted(allocator: std.mem.Allocator, comptime format: []const u8
 fn count_formatted(comptime format: []const u8, args: anytype) usize {
 	var count = io.defaultWritable{};
 
-	debug.assert_try(print_formatted(count.writer(), format, args));
+	print_formatted(count.writer(), format, args) catch unreachable;
 
 	return count.written;
 }

src/main.zig

@@ -6,6 +6,7 @@ const ona = @import("ona");
 
 const Actors = struct {
 	instances: coral.stack.Sequential(ona.gfx.Point2D) = .{.allocator = coral.heap.allocator},
+	quad_mesh_2d: ona.gfx.Handle = .none,
 	body_texture: ona.gfx.Handle = .none,
 };
 
@@ -21,45 +22,29 @@ pub fn main() !void {
 	});
 }
 
-fn load(display: coral.ReadBlocking(ona.gfx.Display), actors: coral.Write(Actors), gfx: ona.gfx.Work) !void {
-	display.res.resize(1280, 720);
+fn load(display: coral.Write(ona.gfx.Display), actors: coral.Write(Actors), assets: coral.Write(ona.gfx.Assets)) !void {
+	display.res.width, display.res.height = .{1280, 720};
+	actors.res.body_texture = try assets.res.open_file("actor.bmp");
+	actors.res.quad_mesh_2d = try assets.res.open_quad_mesh_2d(@splat(1));
 
-	const crap = [_]u32{
-		0xFFFFFFFF, 0xFF000000, 0xFFFFFFFF, 0xFF000000,
-		0xFF000000, 0xFFFFFFFF, 0xFF000000, 0xFFFFFFFF,
-		0xFFFFFFFF, 0xFF000000, 0xFFFFFFFF, 0xFF000000,
-		0xFF000000, 0xFFFFFFFF, 0xFF000000, 0xFFFFFFFF,
-	};
-
-	actors.res.body_texture = try gfx.queue.open(.{
-		.resource = .{
-			.texture = .{
-				.data = coral.io.bytes_of(&crap),
-				.width = 4,
-				.access = .static,
-				.format = .bgra8888,
-			},
-		},
-	});
-
-	try actors.res.instances.push(.{0, 0});
+	try actors.res.instances.push_grow(.{0, 0});
 }
 
 fn exit(actors: coral.Write(Actors)) void {
 	actors.res.instances.deinit();
 }
 
-fn render(gfx: ona.gfx.Work, actors: coral.Write(Actors)) !void {
+fn render(queue: ona.gfx.Queue, actors: coral.Write(Actors)) !void {
 	for (actors.res.instances.values) |instance| {
-		try gfx.queue.draw(.{
+		try queue.commands.append(.{
 			.instance_2d = .{
-				.mesh_2d = gfx.primitives.quad_mesh,
+				.mesh_2d = actors.res.quad_mesh_2d,
 				.texture = actors.res.body_texture,
 
 				.transform = .{
 					.origin = instance,
-					.xbasis = .{100, 0},
-					.ybasis = .{0, 100},
+					.xbasis = .{64, 0},
+					.ybasis = .{0, 64},
 				},
 			},
 		});

src/ona/gfx.zig

@@ -1,37 +1,112 @@
 const App = @import("./App.zig");
 
-pub const Queue = @import("./gfx/Queue.zig");
-
 const coral = @import("coral");
 
-const Device = @import("./gfx/Device.zig");
+const device = @import("./gfx/device.zig");
 
 const ext = @import("./ext.zig");
 
+const formats = @import("./gfx/formats.zig");
+
 const msg = @import("./msg.zig");
 
 const std = @import("std");
 
+pub const Assets = struct {
+	context: device.Context,
+	formats: coral.stack.Sequential(Format),
+	staging_arena: std.heap.ArenaAllocator,
+
+	pub const Format = struct {
+		extension: []const u8,
+		file_desc: *const fn (*std.heap.ArenaAllocator, []const u8) Error!Desc,
+
+		pub const Error = std.mem.Allocator.Error || coral.files.Error || error {
+			FormatUnsupported,
+		};
+	};
+
+	pub fn open_file(self: *Assets, path: []const u8) (std.mem.Allocator.Error || Format.Error)!Handle {
+		defer {
+			const max_cache_size = 536870912;
+
+			if (!self.staging_arena.reset(.{.retain_with_limit = max_cache_size})) {
+				std.log.warn("failed to retain staging arena size of {} bytes", .{max_cache_size});
+			}
+		}
+
+		for (self.formats.values) |format| {
+			if (!std.mem.endsWith(u8, path, format.extension)) {
+				continue;
+			}
+
+			return self.context.open(try format.file_desc(&self.staging_arena, path));
+		}
+
+		return .none;
+	}
+
+	pub fn open_quad_mesh_2d(self: *Assets, extents: Point2D) std.mem.Allocator.Error!Handle {
+		const width, const height = extents / @as(Point2D, @splat(2));
+
+		return self.context.open(.{
+			.mesh_2d = .{
+				.indices = &.{0, 1, 2, 0, 2, 3},
+
+				.vertices = &.{
+					.{.xy = .{-width, height}, .uv = .{0, 1}},
+					.{.xy = .{width, height}, .uv = .{1, 1}},
+					.{.xy = .{width, -height}, .uv = .{1, 0}},
+					.{.xy = .{-width, -height},  .uv = .{0, 0}},
+				},
+			},
+		});
+	}
+};
+
 pub const Color = @Vector(4, f32);
 
+pub const Desc = union (enum) {
+	texture: Texture,
+	mesh_2d: Mesh2D,
+
+	pub const Mesh2D = struct {
+		vertices: []const Vertex,
+		indices: []const u16,
+
+		pub const Vertex = struct {
+			xy: Point2D,
+			uv: Point2D,
+		};
+	};
+
+	pub const Texture = struct {
+		data: []const coral.io.Byte,
+		width: u16,
+		format: Format,
+		access: Access,
+
+		pub const Access = enum {
+			static,
+		};
+
+		pub const Format = enum {
+			rgba8,
+			bgra8,
+
+			pub fn byte_size(self: Format) usize {
+				return switch (self) {
+					.rgba8, .bgra8 => 4,
+				};
+			}
+		};
+	};
+};
+
 pub const Display = struct {
-	sdl_window: *ext.SDL_Window,
-	device: Device,
-
-	pub fn resize(self: Display, width: u16, height: u16) void {
-		ext.SDL_SetWindowSize(self.sdl_window, width, height);
-	}
-
-	pub fn retitle(self: Display, title: []const u8) void {
-		var sentineled_title = [_:0]u8{0} ** 255;
-
-		@memcpy(sentineled_title[0 .. @min(title.len, sentineled_title.len)], title);
-		ext.SDL_SetWindowTitle(self.sdl_window, &sentineled_title);
-	}
-
-	pub fn set_resizable(self: Display, resizable: bool) void {
-		ext.SDL_SetWindowResizable(self.sdl_window, @intFromBool(resizable));
-	}
+	width: u16 = 1280,
+	height: u16 = 720,
+	clear_color: Color = colors.black,
 };
 
 pub const Handle = enum (usize) {
@@ -64,69 +139,62 @@ pub const Input = union (enum) {
 
 pub const Point2D = @Vector(2, f32);
 
+pub const Queue = struct {
+	commands: *device.RenderList,
+
+	pub const State = struct {
+		command_index: usize,
+	};
+
+	pub fn bind(_: coral.system.BindContext) std.mem.Allocator.Error!State {
+		// TODO: Review how good of an idea this global state is, even if bind is guaranteed to always be ran on main.
+		if (renders.is_empty()) {
+			renders = .{.allocator = coral.heap.allocator};
+		}
+
+		const command_index = renders.len();
+
+		try renders.push_grow(device.RenderChain.init(coral.heap.allocator));
+
+		return .{
+			.command_index = command_index,
+		};
+	}
+
+	pub fn init(state: *State) Queue {
+		return .{
+			.commands = renders.values[state.command_index].pending(),
+		};
+	}
+
+	pub fn unbind(state: *State) void {
+		std.debug.assert(!renders.is_empty());
+
+		const render = &renders.values[state.command_index];
+
+		render.deinit();
+		std.mem.swap(device.RenderChain, render, renders.get_ptr().?);
+		std.debug.assert(renders.pop());
+
+		if (renders.is_empty()) {
+			Queue.renders.deinit();
+		}
+	}
+
+	var renders = coral.stack.Sequential(device.RenderChain){.allocator = coral.heap.allocator};
+};
+
 pub const Transform2D = extern struct {
 	xbasis: Point2D = .{1, 0},
 	ybasis: Point2D = .{0, 1},
 	origin: Point2D = @splat(0),
 };
 
-pub const Work = struct {
-	queue: *Queue.Buffer,
-	primitives: *const Primitives,
-
-	const Primitives = struct {
-		quad_mesh: Handle,
-	};
-
-	pub const State = struct {
-		queue: *Queue,
-		primitives: *const Primitives,
-	};
-
-	pub fn bind(context: coral.system.BindContext) std.mem.Allocator.Error!State {
-		const queue = try Queue.create();
-
-		return .{
-			.primitives = (try context.register_read_only_resource_access(.none, Primitives)) orelse create: {
-				const buffer = queue.pending();
-				const half_extent = 0.5;
-
-				try context.world.set_resource(.none, Primitives{
-					.quad_mesh = try buffer.open(.{
-						.label = "quad mesh primitive",
-
-						.resource = .{
-							.mesh_2d = .{
-								.indices = &.{0, 1, 2, 0, 2, 3},
-
-								.vertices = &.{
-									.{.xy = .{-half_extent, half_extent}, .uv = .{0, 1}},
-									.{.xy = .{half_extent, half_extent}, .uv = .{1, 1}},
-									.{.xy = .{half_extent, -half_extent}, .uv = .{1, 0}},
-									.{.xy = .{-half_extent, -half_extent},  .uv = .{0, 0}},
-								},
-							},
-						},
-					}),
-				});
-
-				break: create (try context.register_read_only_resource_access(.none, Primitives)).?;
-			},
-
-			.queue = queue,
-		};
-	}
-
-	pub fn init(state: *State) Work {
-		return .{
-			.queue = state.queue.pending(),
-			.primitives = state.primitives,
-		};
-	}
-
-	pub fn unbind(state: *State) void {
-		state.queue.release();
-	}
+const builtin_formats = [_]Assets.Format{
+	.{
+		.extension = "bmp",
+		.file_desc = formats.bmp_file_desc,
+	},
 };
 
 pub const colors = struct {
@@ -156,43 +224,45 @@ pub fn poll(app: coral.Write(App), inputs: msg.Send(Input)) !void {
 	}
 }
 
-pub fn setup(world: *coral.World, events: App.Events) (error {SDLError} || std.Thread.SpawnError || std.mem.Allocator.Error)!void {
+pub fn setup(world: *coral.World, events: App.Events) (error {Unsupported} || std.Thread.SpawnError || std.mem.Allocator.Error)!void {
 	if (ext.SDL_Init(ext.SDL_INIT_VIDEO) != 0) {
-		return error.SDLError;
+		return error.Unsupported;
 	}
 
-	const sdl_window = create: {
-		const position = ext.SDL_WINDOWPOS_CENTERED;
-		const flags = ext.SDL_WINDOW_OPENGL;
-		const width = 640;
-		const height = 480;
+	var context = try device.Context.init();
 
-		break: create ext.SDL_CreateWindow("Ona", position, position, width, height, flags) orelse {
-			return error.SDLError;
-		};
-	};
+	errdefer context.deinit();
 
-	errdefer ext.SDL_DestroyWindow(sdl_window);
+	var registered_formats = coral.stack.Sequential(Assets.Format){.allocator = coral.heap.allocator};
 
-	var device = try Device.init(sdl_window);
+	errdefer registered_formats.deinit();
 
-	errdefer device.deinit();
+	try registered_formats.grow(builtin_formats.len);
+	std.debug.assert(registered_formats.push_all(&builtin_formats));
 
-	try world.set_resource(.main, Display{
-		.device = device,
-		.sdl_window = sdl_window,
+	try world.set_resource(.none, Assets{
+		.staging_arena = std.heap.ArenaAllocator.init(coral.heap.allocator),
+		.formats = registered_formats,
+		.context = context,
 	});
 
+	try world.set_resource(.none, Display{});
 	try world.on_event(events.pre_update, coral.system_fn(poll), .{.label = "poll gfx"});
 	try world.on_event(events.exit, coral.system_fn(stop), .{.label = "stop gfx"});
-	try world.on_event(events.finish, coral.system_fn(submit), .{.label = "submit gfx"});
+	try world.on_event(events.finish, coral.system_fn(synchronize), .{.label = "synchronize gfx"});
 }
 
-pub fn stop(display: coral.WriteBlocking(Display)) void {
-	display.res.device.deinit();
-	ext.SDL_DestroyWindow(display.res.sdl_window);
+pub fn stop(assets: coral.Write(Assets)) void {
+	assets.res.staging_arena.deinit();
+	assets.res.formats.deinit();
+	assets.res.context.deinit();
 }
 
-pub fn submit(display: coral.WriteBlocking(Display)) void {
-	display.res.device.submit();
+pub fn synchronize(assets: coral.Write(Assets), display: coral.Read(Display)) !void {
+	assets.res.context.submit(.{
+		.width = display.res.width,
+		.height = display.res.height,
+		.clear_color = display.res.clear_color,
+		.renders = Queue.renders.values,
+	});
 }

src/ona/gfx/Device.zig

@@ -1,534 +0,0 @@
-const Queue = @import("./Queue.zig");
-
-const coral = @import("coral");
-
-const ext = @import("../ext.zig");
-
-const gfx = @import("../gfx.zig");
-
-const sokol = @import("sokol");
-
-const std = @import("std");
-
-thread: std.Thread,
-clear_color: gfx.Color = gfx.colors.black,
-state: *State,
-
-const AtomicBool = std.atomic.Value(bool);
-
-const Frame = struct {
-	width: u16,
-	height: u16,
-	flushed_instance_2d_count: usize = 0,
-	pushed_instance_2d_count: usize = 0,
-	mesh_2d: gfx.Handle = .none,
-	texture: gfx.Handle = .none,
-
-	fn unflushed_instance_2d_count(self: Frame) usize {
-		return self.pushed_instance_2d_count - self.flushed_instance_2d_count;
-	}
-};
-
-const Render = struct {
-	resources: coral.stack.Sequential(Resource),
-	instance_2d_pipeline: sokol.gfx.Pipeline,
-	instance_2d_buffers: coral.stack.Sequential(sokol.gfx.Buffer),
-
-	const Instance2D = extern struct {
-		transform: gfx.Transform2D,
-		tint: @Vector(4, u8) = @splat(std.math.maxInt(u8)),
-		depth: f32 = 0,
-		texture_offset: gfx.Point2D = @splat(0),
-		texture_size: gfx.Point2D = @splat(1),
-
-		const buffer_indices = .{
-			.mesh = 0,
-			.instance = 1,
-		};
-
-		const instances_per_buffer = 512;
-
-		const shader = @import("./shaders/instance_2d.glsl.zig");
-	};
-
-	const Resource = union (enum) {
-		empty,
-		mesh_2d: Mesh2D,
-		texture: Texture,
-
-		const Mesh2D = struct {
-			index_count: u32,
-			vertex_buffer: sokol.gfx.Buffer,
-			index_buffer: sokol.gfx.Buffer,
-		};
-
-		const Texture = struct {
-			image: sokol.gfx.Image,
-			sampler: sokol.gfx.Sampler,
-		};
-	};
-
-	fn deinit(self: *Render) void {
-		for (self.instance_2d_buffers.values) |buffer| {
-			sokol.gfx.destroyBuffer(buffer);
-		}
-
-		self.instance_2d_buffers.deinit();
-		sokol.gfx.destroyPipeline(self.instance_2d_pipeline);
-		self.resources.deinit();
-	}
-
-	fn init() Render {
-		sokol.gfx.setup(.{
-			.environment = .{
-				.defaults = .{
-					.color_format = .RGBA8,
-					.depth_format = .DEPTH_STENCIL,
-					.sample_count = 1,
-				},
-			},
-
-			.logger = .{
-				.func = sokol.log.func,
-			},
-		});
-
-		return .{
-			.instance_2d_pipeline = sokol.gfx.makePipeline(.{
-				.label = "2D drawing pipeline",
-
-				.layout = .{
-					.attrs = get: {
-						var attrs = [_]sokol.gfx.VertexAttrState{.{}} ** 16;
-
-						attrs[Instance2D.shader.ATTR_vs_mesh_xy] = .{
-							.format = .FLOAT2,
-							.buffer_index = Instance2D.buffer_indices.mesh,
-						};
-
-						attrs[Instance2D.shader.ATTR_vs_mesh_uv] = .{
-							.format = .FLOAT2,
-							.buffer_index = Instance2D.buffer_indices.mesh,
-						};
-
-						attrs[Instance2D.shader.ATTR_vs_instance_xbasis] = .{
-							.format = .FLOAT2,
-							.buffer_index = Instance2D.buffer_indices.instance,
-						};
-
-						attrs[Instance2D.shader.ATTR_vs_instance_ybasis] = .{
-							.format = .FLOAT2,
-							.buffer_index = Instance2D.buffer_indices.instance,
-						};
-
-						attrs[Instance2D.shader.ATTR_vs_instance_origin] = .{
-							.format = .FLOAT2,
-							.buffer_index = Instance2D.buffer_indices.instance,
-						};
-
-						attrs[Instance2D.shader.ATTR_vs_instance_tint] = .{
-							.format = .UBYTE4N,
-							.buffer_index = Instance2D.buffer_indices.instance,
-						};
-
-						attrs[Instance2D.shader.ATTR_vs_instance_depth] = .{
-							.format = .FLOAT,
-							.buffer_index = Instance2D.buffer_indices.instance,
-						};
-
-						attrs[Instance2D.shader.ATTR_vs_instance_rect] = .{
-							.format = .FLOAT4,
-							.buffer_index = Instance2D.buffer_indices.instance,
-						};
-
-						break: get attrs;
-					},
-
-					.buffers = get: {
-						var buffers = [_]sokol.gfx.VertexBufferLayoutState{.{}} ** 8;
-
-						buffers[Instance2D.buffer_indices.instance].step_func = .PER_INSTANCE;
-
-						break: get buffers;
-					},
-				},
-
-				.shader = sokol.gfx.makeShader(Instance2D.shader.draw2dShaderDesc(sokol.gfx.queryBackend())),
-				.index_type = .UINT16,
-			}),
-
-			.instance_2d_buffers = .{.allocator = coral.heap.allocator},
-			.resources = .{.allocator = coral.heap.allocator},
-		};
-	}
-
-	fn insert_resource(self: *Render, handle: gfx.Handle, resource: Resource) !void {
-		const handle_index = handle.index() orelse {
-			return error.InvalidHandle;
-		};
-
-		const resource_count = self.resources.len();
-
-		if (handle_index < resource_count) {
-			const empty_resource = &self.resources.values[handle_index];
-
-			if (empty_resource.* != .empty) {
-				return error.InvalidHandle;
-			}
-
-			empty_resource.* = resource;
-		} else {
-			if (handle_index != resource_count) {
-				return error.InvalidIndex;
-			}
-
-			try self.resources.push(resource);
-		}
-	}
-
-	fn flush_instance_2ds(self: *Render, frame: *Frame) void {
-		const unflushed_count = frame.unflushed_instance_2d_count();
-
-		if (unflushed_count == 0) {
-			return;
-		}
-
-		sokol.gfx.applyPipeline(self.instance_2d_pipeline);
-
-		sokol.gfx.applyUniforms(.VS, Instance2D.shader.SLOT_Screen, sokol.gfx.asRange(&Instance2D.shader.Screen{
-			.screen_size = .{@floatFromInt(frame.width), @floatFromInt(frame.height)},
-		}));
-
-		const mesh_2d = self.resources.values[frame.mesh_2d.index().?].mesh_2d;
-		const texture = self.resources.values[frame.texture.index().?].texture;
-
-		var bindings = sokol.gfx.Bindings{
-			.vertex_buffers = get: {
-				var buffers = [_]sokol.gfx.Buffer{.{}} ** 8;
-
-				buffers[Instance2D.buffer_indices.mesh] = mesh_2d.vertex_buffer;
-
-				break: get buffers;
-			},
-
-			.index_buffer = mesh_2d.index_buffer,
-
-			.fs = .{
-				.images = get: {
-					var images = [_]sokol.gfx.Image{.{}} ** 12;
-
-					images[0] = texture.image;
-
-					break: get images;
-				},
-
-				.samplers = get: {
-					var samplers = [_]sokol.gfx.Sampler{.{}} ** 8;
-
-					samplers[0] = texture.sampler;
-
-					break: get samplers;
-				},
-			},
-		};
-
-		while (frame.flushed_instance_2d_count < frame.pushed_instance_2d_count) {
-			const buffer_index = frame.flushed_instance_2d_count / Instance2D.instances_per_buffer;
-			const buffer_offset = frame.flushed_instance_2d_count % Instance2D.instances_per_buffer;
-			const instances_to_flush = @min(Instance2D.instances_per_buffer - buffer_offset, unflushed_count);
-
-			bindings.vertex_buffers[Instance2D.buffer_indices.instance] = self.instance_2d_buffers.values[buffer_index];
-			bindings.vertex_buffer_offsets[Instance2D.buffer_indices.instance] = @intCast(buffer_offset);
-
-			sokol.gfx.applyBindings(bindings);
-			sokol.gfx.draw(0, mesh_2d.index_count, @intCast(instances_to_flush));
-
-			frame.flushed_instance_2d_count += instances_to_flush;
-		}
-	}
-
-	fn push_instance_2d(self: *Render, frame: *Frame, command: Queue.DrawCommand.Instance) std.mem.Allocator.Error!void {
-		if (command.mesh_2d != frame.mesh_2d or command.texture != frame.texture) {
-			self.flush_instance_2ds(frame);
-		}
-
-		frame.mesh_2d = command.mesh_2d;
-		frame.texture = command.texture;
-
-		const has_filled_buffer = (frame.pushed_instance_2d_count % Instance2D.instances_per_buffer) == 0;
-		const pushed_buffer_count = frame.pushed_instance_2d_count / Instance2D.instances_per_buffer;
-
-		if (has_filled_buffer and pushed_buffer_count == self.instance_2d_buffers.len()) {
-			const instance_buffer = sokol.gfx.makeBuffer(.{
-				.size = @sizeOf(Instance2D) * Instance2D.instances_per_buffer,
-				.usage = .STREAM,
-				.label = "2D drawing instance buffer",
-			});
-
-			errdefer sokol.gfx.destroyBuffer(instance_buffer);
-
-			try self.instance_2d_buffers.push(instance_buffer);
-		}
-
-		_ = sokol.gfx.appendBuffer(self.instance_2d_buffers.get().?, sokol.gfx.asRange(&Instance2D{
-			.transform = command.transform,
-		}));
-
-		frame.pushed_instance_2d_count += 1;
-	}
-
-	fn remove_resource(self: *Render, handle: gfx.Handle) ?Resource {
-		if (handle.index()) |handle_index| {
-			const resource = self.resources.values[handle_index];
-
-			if (resource != .empty) {
-				self.resources.values[handle_index] = .empty;
-
-				return resource;
-			}
-		}
-
-		return null;
-	}
-};
-
-const Self = @This();
-
-const State = struct {
-	finished: std.Thread.Semaphore = .{},
-	is_running: AtomicBool = AtomicBool.init(true),
-	ready: std.Thread.Semaphore = .{},
-	clear_color: gfx.Color = gfx.colors.black,
-};
-
-pub fn deinit(self: *Self) void {
-	self.state.is_running.store(false, .monotonic);
-	self.state.ready.post();
-	self.thread.join();
-	coral.heap.allocator.destroy(self.state);
-
-	self.* = undefined;
-}
-
-pub fn init(window: *ext.SDL_Window) (std.mem.Allocator.Error || std.Thread.SpawnError)!Self {
-	const state = try coral.heap.allocator.create(State);
-
-	errdefer coral.heap.allocator.destroy(state);
-
-	state.* = .{};
-
-	const thread = try std.Thread.spawn(.{}, run, .{window, state});
-
-	thread.setName("Ona Graphics") catch {
-		std.log.warn("failed to name the graphics thread", .{});
-	};
-
-	return .{
-		.thread = thread,
-		.state = state,
-	};
-}
-
-fn process_close_command(command: Queue.CloseCommand, rendering: *Render) !void {
-	const resource = &rendering.resources.values[command.handle.index().?];
-
-	switch (resource.*) {
-		.empty => {}, // TODO: Handle this.
-
-		.mesh_2d => |mesh_2d| {
-			sokol.gfx.destroyBuffer(mesh_2d.vertex_buffer);
-			sokol.gfx.destroyBuffer(mesh_2d.index_buffer);
-		},
-
-		.texture => |texture| {
-			sokol.gfx.destroyImage(texture.image);
-			sokol.gfx.destroySampler(texture.sampler);
-		},
-	}
-
-	resource.* = .empty;
-}
-
-fn process_draw_command(command: Queue.DrawCommand, render: *Render, frame: *Frame) !void {
-	switch (command) {
-		.instance_2d => |instance_2d| {
-			try render.push_instance_2d(frame, instance_2d);
-		},
-
-		.post_process => |post_process| {
-			render.flush_instance_2ds(frame);
-			// sokol.gfx.applyPipeline(self.post_process_pipeline);
-
-			_ = post_process;
-		},
-	}
-
-	render.flush_instance_2ds(frame);
-}
-
-fn process_open_command(command: Queue.OpenCommand, render: *Render) !void {
-	switch (command.resource) {
-		.texture => |texture| {
-			const stride = texture.width * texture.format.byte_size();
-
-			const image = sokol.gfx.makeImage(.{
-				.width = texture.width,
-				.height = @intCast(texture.data.len / stride),
-
-				.data = .{
-					.subimage = get: {
-						var subimage = [_][16]sokol.gfx.Range{.{.{}} ** 16} ** 6;
-
-						subimage[0][0] = sokol.gfx.asRange(texture.data);
-
-						break: get subimage;
-					},
-				},
-			});
-
-			errdefer sokol.gfx.destroyImage(image);
-
-			const sampler = sokol.gfx.makeSampler(.{});
-
-			errdefer sokol.gfx.destroySampler(sampler);
-
-			try render.insert_resource(command.handle, .{
-				.texture = .{
-					.sampler = sampler,
-					.image = image,
-				},
-			});
-		},
-
-		.mesh_2d => |mesh_2d| {
-			const index_buffer = sokol.gfx.makeBuffer(.{
-				.data = sokol.gfx.asRange(mesh_2d.indices),
-				.type = .INDEXBUFFER,
-			});
-
-			const vertex_buffer = sokol.gfx.makeBuffer(.{
-				.data = sokol.gfx.asRange(mesh_2d.vertices),
-				.type = .VERTEXBUFFER,
-			});
-
-			errdefer {
-				sokol.gfx.destroyBuffer(index_buffer);
-				sokol.gfx.destroyBuffer(vertex_buffer);
-			}
-
-			if (mesh_2d.indices.len > std.math.maxInt(u32)) {
-				return error.OutOfMemory;
-			}
-
-			try render.insert_resource(command.handle, .{
-				.mesh_2d = .{
-					.index_buffer = index_buffer,
-					.vertex_buffer = vertex_buffer,
-					.index_count = @intCast(mesh_2d.indices.len),
-				},
-			});
-		},
-	}
-}
-
-fn run(window: *ext.SDL_Window, state: *State) !void {
-	const context = configure_and_create: {
-		var result = @as(c_int, 0);
-
-		result |= ext.SDL_GL_SetAttribute(ext.SDL_GL_CONTEXT_FLAGS, ext.SDL_GL_CONTEXT_FORWARD_COMPATIBLE_FLAG);
-		result |= ext.SDL_GL_SetAttribute(ext.SDL_GL_CONTEXT_PROFILE_MASK, ext.SDL_GL_CONTEXT_PROFILE_CORE);
-		result |= ext.SDL_GL_SetAttribute(ext.SDL_GL_CONTEXT_MAJOR_VERSION, 3);
-		result |= ext.SDL_GL_SetAttribute(ext.SDL_GL_CONTEXT_MINOR_VERSION, 3);
-		result |= ext.SDL_GL_SetAttribute(ext.SDL_GL_DOUBLEBUFFER, 1);
-
-		if (result != 0) {
-			return error.Unsupported;
-		}
-
-		break: configure_and_create ext.SDL_GL_CreateContext(window);
-	};
-
-	sokol.gfx.setup(.{
-		.environment = .{
-			.defaults = .{
-				.color_format = .RGBA8,
-				.depth_format = .DEPTH_STENCIL,
-				.sample_count = 1,
-			},
-		},
-
-		.logger = .{
-			.func = sokol.log.func,
-		},
-	});
-
-	defer {
-		sokol.gfx.shutdown();
-		ext.SDL_GL_DeleteContext(context);
-	}
-
-	var render = Render.init();
-
-	defer render.deinit();
-
-	state.finished.post();
-
-	while (state.is_running.load(.monotonic)) {
-		state.ready.wait();
-
-		defer state.finished.post();
-
-		var frame = init_frame: {
-			var width, var height = [_]c_int{0, 0};
-
-			ext.SDL_GL_GetDrawableSize(window, &width, &height);
-			std.debug.assert(width > 0 and height > 0);
-
-			break: init_frame Frame{
-				.width = @intCast(width),
-				.height = @intCast(height),
-			};
-		};
-
-		sokol.gfx.beginPass(.{
-			.swapchain = .{
-				.width = frame.width,
-				.height = frame.height,
-				.sample_count = 1,
-				.color_format = .RGBA8,
-				.depth_format = .DEPTH_STENCIL,
-				.gl = .{.framebuffer = 0},
-			},
-
-			.action = .{
-				.colors = get: {
-					var actions = [_]sokol.gfx.ColorAttachmentAction{.{}} ** 4;
-
-					actions[0] = .{
-						.load_action = .CLEAR,
-						.clear_value = @as(sokol.gfx.Color, @bitCast(state.clear_color)),
-					};
-
-					break: get actions;
-				},
-			},
-		});
-
-		try Queue.visit_open_commands(process_open_command, .{&render});
-		try Queue.visit_draw_commands(process_draw_command, .{&render, &frame});
-		try Queue.visit_close_commands(process_close_command, .{&render});
-
-		sokol.gfx.endPass();
-		sokol.gfx.commit();
-		ext.SDL_GL_SwapWindow(window);
-	}
-}
-
-pub fn submit(self: *Self) void {
-	self.state.finished.wait();
-
-	self.state.clear_color = self.clear_color;
-
-	Queue.swap();
-	self.state.ready.post();
-}

src/ona/gfx/Queue.zig

@@ -1,309 +0,0 @@
-const coral = @import("coral");
-
-const gfx = @import("../gfx.zig");
-
-const std = @import("std");
-
-buffers: [2]Buffer,
-is_swapped: bool = false,
-ref_count: AtomicCount = AtomicCount.init(1),
-has_next: ?*Self = null,
-has_prev: ?*Self = null,
-
-const AtomicCount = std.atomic.Value(usize);
-
-pub const Buffer = struct {
-	arena: std.heap.ArenaAllocator,
-	closed_handles: coral.stack.Sequential(usize),
-	open_commands: coral.stack.Sequential(OpenCommand),
-	draw_commands: coral.stack.Sequential(DrawCommand),
-	close_commands: coral.stack.Sequential(CloseCommand),
-
-	pub fn clear(self: *Buffer) void {
-		self.close_commands.clear();
-		self.draw_commands.clear();
-		self.open_commands.clear();
-
-		if (!self.arena.reset(.retain_capacity)) {
-			std.log.warn("failed to reset the buffer of a gfx queue with retained capacity", .{});
-		}
-	}
-
-	fn deinit(self: *Buffer) void {
-		self.arena.deinit();
-		self.closed_handles.deinit();
-		self.open_commands.deinit();
-		self.draw_commands.deinit();
-		self.close_commands.deinit();
-	}
-
-	fn init(allocator: std.mem.Allocator) Buffer {
-		return .{
-			.arena = std.heap.ArenaAllocator.init(allocator),
-			.closed_handles = .{.allocator = allocator},
-			.open_commands = .{.allocator = allocator},
-			.draw_commands = .{.allocator = allocator},
-			.close_commands = .{.allocator = allocator},
-		};
-	}
-
-	pub fn draw(self: *Buffer, command: DrawCommand) std.mem.Allocator.Error!void {
-		try self.draw_commands.push(switch (command) {
-			.instance_2d => |instance_2d| .{.instance_2d = instance_2d},
-			.post_process => |post_process| .{.post_process = post_process},
-		});
-	}
-
-	pub fn open(self: *Buffer, command: OpenCommand) std.mem.Allocator.Error!gfx.Handle {
-		const reserved_handle = @as(gfx.Handle, switch (command.handle) {
-			.none => @enumFromInt(reserve_handle: {
-				if (self.closed_handles.get()) |handle| {
-					std.debug.assert(self.closed_handles.pop());
-
-					break: reserve_handle handle;
-				}
-
-				break: reserve_handle next_handle.fetchAdd(1, .monotonic);
-			}),
-
-			_ => |handle| handle,
-		});
-
-		std.debug.assert(reserved_handle != .none);
-
-		const arena_allocator = self.arena.allocator();
-
-		try self.open_commands.push(.{
-			.resource = switch (command.resource) {
-				.texture => |texture| .{
-					.texture = .{
-						.data = try arena_allocator.dupe(coral.io.Byte, texture.data),
-						.width = texture.width,
-						.format = texture.format,
-						.access = texture.access,
-					},
-				},
-
-				.mesh_2d => |mesh_2d| .{
-					.mesh_2d = .{
-						.indices = try arena_allocator.dupe(u16, mesh_2d.indices),
-						.vertices = try arena_allocator.dupe(OpenCommand.Mesh2D.Vertex, mesh_2d.vertices),
-					},
-				},
-			},
-
-			.label = if (command.label) |label| try arena_allocator.dupe(coral.io.Byte, label) else null,
-			.handle = reserved_handle,
-		});
-
-		return reserved_handle;
-	}
-};
-
-pub const CloseCommand = struct {
-	handle: gfx.Handle,
-};
-
-pub const DrawCommand = union (enum) {
-	instance_2d: Instance,
-	post_process: PostProcess,
-
-	pub const Instance = struct {
-		texture: gfx.Handle,
-		mesh_2d: gfx.Handle,
-		transform: gfx.Transform2D,
-	};
-
-	pub const PostProcess = struct {
-
-	};
-};
-
-pub const OpenCommand = struct {
-	handle: gfx.Handle = .none,
-	label: ?[]const u8 = null,
-
-	resource: union (enum) {
-		texture: Texture,
-		mesh_2d: Mesh2D,
-	},
-
-	pub const Mesh2D = struct {
-		vertices: []const Vertex,
-		indices: []const u16,
-
-		pub const Vertex = struct {
-			xy: gfx.Point2D,
-			uv: gfx.Point2D,
-		};
-	};
-
-	pub const Texture = struct {
-		data: []const coral.io.Byte,
-		width: u16,
-		format: Format,
-		access: Access,
-
-		pub const Access = enum {
-			static,
-		};
-
-		pub const Format = enum {
-			rgba8888,
-			bgra8888,
-			argb8888,
-			rgb888,
-			bgr888,
-
-			pub fn byte_size(self: Format) usize {
-				return switch (self) {
-					.rgba8888, .bgra8888, .argb8888 => 4,
-					.rgb888, .bgr888 => 3,
-				};
-			}
-		};
-	};
-};
-
-pub fn acquire(self: *Self) void {
-	self.ref_count.fetchAdd(1, .monotonic);
-}
-
-pub fn create() std.mem.Allocator.Error!*Self {
-	const queue = try coral.heap.allocator.create(Self);
-
-	errdefer coral.heap.allocator.destroy(queue);
-
-	queue.* = .{
-		.buffers = .{Buffer.init(coral.heap.allocator), Buffer.init(coral.heap.allocator)},
-	};
-
-	mutex.lock();
-
-	defer mutex.unlock();
-
-	if (has_tail) |tail| {
-		tail.has_next = queue;
-		queue.has_prev = tail;
-	} else {
-		std.debug.assert(has_head == null);
-
-		has_head = queue;
-	}
-
-	has_tail = queue;
-
-	return queue;
-}
-
-pub fn pending(self: *Self) *Buffer {
-	return &self.buffers[@intFromBool(self.is_swapped)];
-}
-
-pub fn release(self: *Self) void {
-	if (self.ref_count.fetchSub(1, .monotonic) == 1) {
-		mutex.lock();
-
-		defer mutex.unlock();
-
-		if (self.has_prev) |prev| {
-			prev.has_next = self.has_next;
-		} else {
-			has_head = self.has_next;
-		}
-
-		if (self.has_next) |next| {
-			next.has_prev = self.has_prev;
-		} else {
-			has_tail = self.has_prev;
-		}
-
-		for (&self.buffers) |*buffer| {
-			buffer.deinit();
-		}
-
-		coral.heap.allocator.destroy(self);
-	}
-}
-
-pub fn submitted(self: *Self) *Buffer {
-	return &self.buffers[@intFromBool(!self.is_swapped)];
-}
-
-const Self = @This();
-
-var has_head = @as(?*Self, null);
-
-var has_tail = @as(?*Self, null);
-
-var mutex = std.Thread.Mutex{};
-
-var next_handle = AtomicCount.init(1);
-
-pub fn swap() void {
-	mutex.lock();
-
-	defer mutex.unlock();
-
-	var has_node = has_head;
-
-	while (has_node) |node| : (has_node = node.has_next) {
-		node.is_swapped = !node.is_swapped;
-
-		node.pending().clear();
-	}
-}
-
-pub fn visit_close_commands(visit: anytype, args: anytype) !void {
-	mutex.lock();
-
-	defer mutex.unlock();
-
-	var has_node = has_head;
-	var iterations = @as(usize, 0);
-
-	while (has_node) |node| : ({
-		has_node = node.has_next;
-		iterations += 1;
-	}) {
-		for (node.submitted().close_commands.values) |command| {
-			try @call(.auto, visit, .{command} ++ args);
-		}
-	}
-}
-
-pub fn visit_draw_commands(visit: anytype, args: anytype) !void {
-	mutex.lock();
-
-	defer mutex.unlock();
-
-	var has_node = has_head;
-	var iterations = @as(usize, 0);
-
-	while (has_node) |node| : ({
-		has_node = node.has_next;
-		iterations += 1;
-	}) {
-		for (node.submitted().draw_commands.values) |command| {
-			try @call(.auto, visit, .{command} ++ args);
-		}
-	}
-}
-
-pub fn visit_open_commands(visit: anytype, args: anytype) !void {
-	mutex.lock();
-
-	defer mutex.unlock();
-
-	var has_node = has_head;
-	var iterations = @as(usize, 0);
-
-	while (has_node) |node| : ({
-		has_node = node.has_next;
-		iterations += 1;
-	}) {
-		for (node.submitted().open_commands.values) |command| {
-			try @call(.auto, visit, .{command} ++ args);
-		}
-	}
-}

src/ona/gfx/commands.zig

@@ -0,0 +1,80 @@
+const coral = @import("coral");
+
+const std = @import("std");
+
+pub fn Chain(comptime Command: type, comptime clone_command: ?Clone(Command)) type {
+	return struct {
+		swap_lists: [2]CommandList,
+		swap_state: u1 = 0,
+
+		const CommandList = List(Command, clone_command);
+
+		const Self = @This();
+
+		pub fn deinit(self: *Self) void {
+			for (&self.swap_lists) |*list| {
+				list.deinit();
+			}
+
+			self.* = undefined;
+		}
+
+		pub fn init(allocator: std.mem.Allocator) Self {
+			return .{
+				.swap_lists = .{CommandList.init(allocator), CommandList.init(allocator)},
+			};
+		}
+
+		pub fn pending(self: *Self) *CommandList {
+			return &self.swap_lists[self.swap_state];
+		}
+
+		pub fn submitted(self: *Self) *CommandList {
+			return &self.swap_lists[self.swap_state ^ 1];
+		}
+
+		pub fn swap(self: *Self) void {
+			self.swap_state ^= 1;
+		}
+	};
+}
+
+pub fn Clone(comptime Command: type) type {
+	return fn (Command, *std.heap.ArenaAllocator) std.mem.Allocator.Error!Command;
+}
+
+pub fn List(comptime Command: type, comptime clone_command: ?Clone(Command)) type {
+	return struct {
+		arena: std.heap.ArenaAllocator,
+		stack: coral.stack.Sequential(Command),
+
+		const Self = @This();
+
+		pub fn append(self: *Self, command: Command) std.mem.Allocator.Error!void {
+			return self.stack.push_grow(if (clone_command) |clone| try clone(command, &self.arena) else command);
+		}
+
+		pub fn clear(self: *Self) void {
+			self.stack.clear();
+
+			if (!self.arena.reset(.retain_capacity)) {
+				std.log.warn("failed to reset the buffer of a gfx queue with retained capacity", .{});
+			}
+		}
+
+		pub fn deinit(self: *Self) void {
+			self.arena.deinit();
+			self.stack.deinit();
+
+			self.* = undefined;
+		}
+
+		pub fn init(allocator: std.mem.Allocator) Self {
+			return .{
+				.arena = std.heap.ArenaAllocator.init(allocator),
+				.stack = .{.allocator = allocator},
+			};
+		}
+	};
+}
+

src/ona/gfx/device.zig

@@ -0,0 +1,691 @@
+const commands = @import("./commands.zig");
+
+const coral = @import("coral");
+
+const ext = @import("../ext.zig");
+
+const gfx = @import("../gfx.zig");
+
+const sokol = @import("sokol");
+
+const std = @import("std");
+
+pub const Context = struct {
+	window: *ext.SDL_Window,
+	thread: std.Thread,
+	loop: *Loop,
+
+	pub const Submission = struct {
+		width: u16,
+		height: u16,
+		clear_color: gfx.Color = gfx.colors.black,
+		renders: []RenderChain,
+	};
+
+	pub fn close(self: *Context, handle: gfx.Handle) void {
+		const handle_index = handle.index() orelse {
+			return;
+		};
+
+		const close_commands = self.loop.closes.pending();
+
+		std.debug.assert(close_commands.stack.cap > close_commands.stack.len());
+		close_commands.append(.{.index = handle_index}) catch unreachable;
+	}
+
+	pub fn deinit(self: *Context) void {
+		self.loop.is_running.store(false, .monotonic);
+		self.loop.ready.post();
+		self.thread.join();
+		self.loop.deinit();
+		coral.heap.allocator.destroy(self.loop);
+		ext.SDL_DestroyWindow(self.window);
+
+		self.* = undefined;
+	}
+
+	pub fn init() !Context {
+		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;
+			};
+		};
+
+		errdefer ext.SDL_DestroyWindow(window);
+
+		const loop = try coral.heap.allocator.create(Loop);
+
+		errdefer coral.heap.allocator.destroy(loop);
+
+		loop.* = .{};
+
+		return .{
+			.loop = loop,
+			.window = window,
+
+			.thread = spawn: {
+				const thread = try std.Thread.spawn(.{}, Loop.run, .{loop, window});
+
+				thread.setName("Ona Graphics") catch {
+					std.log.warn("failed to name the graphics thread", .{});
+				};
+
+				break: spawn thread;
+			},
+		};
+	}
+
+	pub fn open(self: *Context, desc: gfx.Desc) std.mem.Allocator.Error!gfx.Handle {
+		const open_commands = self.loop.opens.pending();
+		const index = self.loop.closed_indices.get() orelse open_commands.stack.len();
+
+		try open_commands.append(.{
+			.index = index,
+			.desc = desc,
+		});
+
+		const pending_closes = self.loop.closes.pending();
+
+		if (pending_closes.stack.len() == pending_closes.stack.cap) {
+			try pending_closes.stack.grow(1);
+		}
+
+		_ = self.loop.closed_indices.pop();
+
+		return @enumFromInt(index + 1);
+	}
+
+	pub fn submit(self: *Context, submission: Submission) void {
+		self.loop.finished.wait();
+
+		defer self.loop.ready.post();
+
+		for (submission.renders) |*render| {
+			render.swap();
+		}
+
+		self.loop.opens.swap();
+		self.loop.closes.swap();
+
+		var last_width, var last_height = [_]c_int{0, 0};
+
+		ext.SDL_GetWindowSize(self.window, &last_width, &last_height);
+
+		if (submission.width != last_width or submission.height != last_height) {
+			ext.SDL_SetWindowSize(self.window, submission.width, submission.height);
+		}
+
+		self.loop.clear_color = submission.clear_color;
+		self.loop.renders = submission.renders;
+
+		self.loop.ready.post();
+	}
+};
+
+const Loop = struct {
+	ready: std.Thread.Semaphore = .{},
+	finished: std.Thread.Semaphore = .{},
+	clear_color: gfx.Color = gfx.colors.black,
+	is_running: AtomicBool = AtomicBool.init(true),
+	renders: []RenderChain = &.{},
+	closes: CloseChain = CloseChain.init(coral.heap.allocator),
+	opens: OpenChain = OpenChain.init(coral.heap.allocator),
+	closed_indices: coral.stack.Sequential(usize) = .{.allocator = coral.heap.allocator},
+
+	const AtomicBool = std.atomic.Value(bool);
+
+	const CloseCommand = struct {
+		index: usize,
+	};
+
+	const OpenCommand = struct {
+		index: usize,
+		desc: gfx.Desc,
+
+		fn clone(command: OpenCommand, arena: *std.heap.ArenaAllocator) std.mem.Allocator.Error!OpenCommand {
+			const allocator = arena.allocator();
+
+			return .{
+				.desc = switch (command.desc) {
+					.texture => |texture| .{
+						.texture = .{
+							.data = try allocator.dupe(coral.io.Byte, texture.data),
+							.width = texture.width,
+							.format = texture.format,
+							.access = texture.access,
+						},
+					},
+
+					.mesh_2d => |mesh_2d| .{
+						.mesh_2d = .{
+							.vertices = try allocator.dupe(gfx.Desc.Mesh2D.Vertex, mesh_2d.vertices),
+							.indices = try allocator.dupe(u16, mesh_2d.indices),
+						},
+					},
+				},
+
+				.index = command.index,
+			};
+		}
+	};
+
+	const CloseChain = commands.Chain(CloseCommand, null);
+
+	const OpenChain = commands.Chain(OpenCommand, OpenCommand.clone);
+
+	fn deinit(self: *Loop) void {
+		self.closes.deinit();
+		self.opens.deinit();
+		self.closed_indices.deinit();
+	}
+
+	fn run(self: *Loop, window: *ext.SDL_Window) !void {
+		const context = configure_and_create: {
+			var result = @as(c_int, 0);
+
+			result |= ext.SDL_GL_SetAttribute(ext.SDL_GL_CONTEXT_FLAGS, ext.SDL_GL_CONTEXT_FORWARD_COMPATIBLE_FLAG);
+			result |= ext.SDL_GL_SetAttribute(ext.SDL_GL_CONTEXT_PROFILE_MASK, ext.SDL_GL_CONTEXT_PROFILE_CORE);
+			result |= ext.SDL_GL_SetAttribute(ext.SDL_GL_CONTEXT_MAJOR_VERSION, 3);
+			result |= ext.SDL_GL_SetAttribute(ext.SDL_GL_CONTEXT_MINOR_VERSION, 3);
+			result |= ext.SDL_GL_SetAttribute(ext.SDL_GL_DOUBLEBUFFER, 1);
+
+			if (result != 0) {
+				return error.Unsupported;
+			}
+
+			break: configure_and_create ext.SDL_GL_CreateContext(window);
+		};
+
+		sokol.gfx.setup(.{
+			.environment = .{
+				.defaults = .{
+					.color_format = .RGBA8,
+					.depth_format = .DEPTH_STENCIL,
+					.sample_count = 1,
+				},
+			},
+
+			.logger = .{
+				.func = sokol.log.func,
+			},
+		});
+
+		defer {
+			sokol.gfx.shutdown();
+			ext.SDL_GL_DeleteContext(context);
+		}
+
+		var rendering = Rendering.init();
+
+		defer rendering.deinit();
+
+		self.finished.post();
+
+		while (self.is_running.load(.monotonic)) {
+			self.ready.wait();
+
+			defer self.finished.post();
+
+			const open_commands = self.opens.submitted();
+
+			defer open_commands.clear();
+
+			for (open_commands.stack.values) |command| {
+				switch (command.desc) {
+					.texture => |texture| {
+						const stride = texture.width * texture.format.byte_size();
+
+						const image = sokol.gfx.makeImage(.{
+							.width = texture.width,
+							.height = @intCast(texture.data.len / stride),
+
+							.data = .{
+								.subimage = get: {
+									var subimage = [_][16]sokol.gfx.Range{.{.{}} ** 16} ** 6;
+
+									subimage[0][0] = sokol.gfx.asRange(texture.data);
+
+									break: get subimage;
+								},
+							},
+
+							.pixel_format = switch (texture.format) {
+								.rgba8 => .RGBA8,
+								.bgra8 => .BGRA8,
+							},
+						});
+
+						errdefer sokol.gfx.destroyImage(image);
+
+						const sampler = sokol.gfx.makeSampler(.{});
+
+						errdefer sokol.gfx.destroySampler(sampler);
+
+						try rendering.insert_object(command.index, .{
+							.texture = .{
+								.sampler = sampler,
+								.image = image,
+							},
+						});
+					},
+
+					.mesh_2d => |mesh_2d| {
+						const index_buffer = sokol.gfx.makeBuffer(.{
+							.data = sokol.gfx.asRange(mesh_2d.indices),
+							.type = .INDEXBUFFER,
+						});
+
+						const vertex_buffer = sokol.gfx.makeBuffer(.{
+							.data = sokol.gfx.asRange(mesh_2d.vertices),
+							.type = .VERTEXBUFFER,
+						});
+
+						errdefer {
+							sokol.gfx.destroyBuffer(index_buffer);
+							sokol.gfx.destroyBuffer(vertex_buffer);
+						}
+
+						if (mesh_2d.indices.len > std.math.maxInt(u32)) {
+							return error.OutOfMemory;
+						}
+
+						try rendering.insert_object(command.index, .{
+							.mesh_2d = .{
+								.index_buffer = index_buffer,
+								.vertex_buffer = vertex_buffer,
+								.index_count = @intCast(mesh_2d.indices.len),
+							},
+						});
+					},
+				}
+			}
+
+			var frame = init_frame: {
+				var width, var height = [_]c_int{0, 0};
+
+				ext.SDL_GL_GetDrawableSize(window, &width, &height);
+				std.debug.assert(width > 0 and height > 0);
+
+				break: init_frame Rendering.Frame{
+					.width = @intCast(width),
+					.height = @intCast(height),
+				};
+			};
+
+			sokol.gfx.beginPass(.{
+				.swapchain = .{
+					.width = frame.width,
+					.height = frame.height,
+					.sample_count = 1,
+					.color_format = .RGBA8,
+					.depth_format = .DEPTH_STENCIL,
+					.gl = .{.framebuffer = 0},
+				},
+
+				.action = .{
+					.colors = get: {
+						var actions = [_]sokol.gfx.ColorAttachmentAction{.{}} ** 4;
+
+						actions[0] = .{
+							.load_action = .CLEAR,
+							.clear_value = @as(sokol.gfx.Color, @bitCast(self.clear_color)),
+						};
+
+						break: get actions;
+					},
+				},
+			});
+
+			for (self.renders) |*render| {
+				const render_commands = render.submitted();
+
+				defer render_commands.clear();
+
+				for (render_commands.stack.values) |command| {
+					switch (command) {
+						.instance_2d => |instance_2d| {
+							try rendering.push_instance_2d(&frame, instance_2d);
+						},
+
+						.post_process => |post_process| {
+							rendering.flush_instance_2ds(&frame);
+							// sokol.gfx.applyPipeline(self.post_process_pipeline);
+
+							_ = post_process;
+						},
+					}
+				}
+			}
+
+			rendering.flush_instance_2ds(&frame);
+			sokol.gfx.endPass();
+			sokol.gfx.commit();
+			ext.SDL_GL_SwapWindow(window);
+
+			const close_commands = self.closes.submitted();
+
+			defer close_commands.clear();
+
+			for (close_commands.stack.values) |command| {
+				const object = &rendering.objects.values[command.index];
+
+				switch (object.*) {
+					.empty => {}, // TODO: Handle double-closes.
+
+					.mesh_2d => |mesh_2d| {
+						sokol.gfx.destroyBuffer(mesh_2d.vertex_buffer);
+						sokol.gfx.destroyBuffer(mesh_2d.index_buffer);
+					},
+
+					.texture => |texture| {
+						sokol.gfx.destroyImage(texture.image);
+						sokol.gfx.destroySampler(texture.sampler);
+					},
+				}
+
+				object.* = .empty;
+			}
+		}
+	}
+};
+
+const Rendering = struct {
+	objects: coral.stack.Sequential(Object),
+	instance_2d_pipeline: sokol.gfx.Pipeline,
+	instance_2d_buffers: coral.stack.Sequential(sokol.gfx.Buffer),
+
+	const Instance2D = extern struct {
+		transform: gfx.Transform2D,
+		tint: @Vector(4, u8) = @splat(std.math.maxInt(u8)),
+		depth: f32 = 0,
+		texture_offset: gfx.Point2D = @splat(0),
+		texture_size: gfx.Point2D = @splat(1),
+
+		const buffer_indices = .{
+			.mesh = 0,
+			.instance = 1,
+		};
+
+		const instances_per_buffer = 512;
+
+		const shader = @import("./shaders/instance_2d.glsl.zig");
+	};
+
+	const Frame = struct {
+		width: u16,
+		height: u16,
+		flushed_instance_2d_count: usize = 0,
+		pushed_instance_2d_count: usize = 0,
+		mesh_2d: gfx.Handle = .none,
+		texture: gfx.Handle = .none,
+
+		fn unflushed_instance_2d_count(self: Frame) usize {
+			return self.pushed_instance_2d_count - self.flushed_instance_2d_count;
+		}
+	};
+
+	const Object = union (enum) {
+		empty,
+
+		mesh_2d: struct {
+			index_count: u32,
+			vertex_buffer: sokol.gfx.Buffer,
+			index_buffer: sokol.gfx.Buffer,
+		},
+
+		texture: struct {
+			image: sokol.gfx.Image,
+			sampler: sokol.gfx.Sampler,
+		},
+	};
+
+	fn deinit(self: *Rendering) void {
+		for (self.instance_2d_buffers.values) |buffer| {
+			sokol.gfx.destroyBuffer(buffer);
+		}
+
+		self.instance_2d_buffers.deinit();
+		sokol.gfx.destroyPipeline(self.instance_2d_pipeline);
+		self.objects.deinit();
+	}
+
+	fn init() Rendering {
+		sokol.gfx.setup(.{
+			.environment = .{
+				.defaults = .{
+					.color_format = .RGBA8,
+					.depth_format = .DEPTH_STENCIL,
+					.sample_count = 1,
+				},
+			},
+
+			.logger = .{
+				.func = sokol.log.func,
+			},
+		});
+
+		return .{
+			.instance_2d_pipeline = sokol.gfx.makePipeline(.{
+				.label = "2D drawing pipeline",
+
+				.layout = .{
+					.attrs = get: {
+						var attrs = [_]sokol.gfx.VertexAttrState{.{}} ** 16;
+
+						attrs[Instance2D.shader.ATTR_vs_mesh_xy] = .{
+							.format = .FLOAT2,
+							.buffer_index = Instance2D.buffer_indices.mesh,
+						};
+
+						attrs[Instance2D.shader.ATTR_vs_mesh_uv] = .{
+							.format = .FLOAT2,
+							.buffer_index = Instance2D.buffer_indices.mesh,
+						};
+
+						attrs[Instance2D.shader.ATTR_vs_instance_xbasis] = .{
+							.format = .FLOAT2,
+							.buffer_index = Instance2D.buffer_indices.instance,
+						};
+
+						attrs[Instance2D.shader.ATTR_vs_instance_ybasis] = .{
+							.format = .FLOAT2,
+							.buffer_index = Instance2D.buffer_indices.instance,
+						};
+
+						attrs[Instance2D.shader.ATTR_vs_instance_origin] = .{
+							.format = .FLOAT2,
+							.buffer_index = Instance2D.buffer_indices.instance,
+						};
+
+						attrs[Instance2D.shader.ATTR_vs_instance_tint] = .{
+							.format = .UBYTE4N,
+							.buffer_index = Instance2D.buffer_indices.instance,
+						};
+
+						attrs[Instance2D.shader.ATTR_vs_instance_depth] = .{
+							.format = .FLOAT,
+							.buffer_index = Instance2D.buffer_indices.instance,
+						};
+
+						attrs[Instance2D.shader.ATTR_vs_instance_rect] = .{
+							.format = .FLOAT4,
+							.buffer_index = Instance2D.buffer_indices.instance,
+						};
+
+						break: get attrs;
+					},
+
+					.buffers = get: {
+						var buffers = [_]sokol.gfx.VertexBufferLayoutState{.{}} ** 8;
+
+						buffers[Instance2D.buffer_indices.instance].step_func = .PER_INSTANCE;
+
+						break: get buffers;
+					},
+				},
+
+				.shader = sokol.gfx.makeShader(Instance2D.shader.draw2dShaderDesc(sokol.gfx.queryBackend())),
+				.index_type = .UINT16,
+			}),
+
+			.instance_2d_buffers = .{.allocator = coral.heap.allocator},
+			.objects = .{.allocator = coral.heap.allocator},
+		};
+	}
+
+	fn flush_instance_2ds(self: *Rendering, frame: *Frame) void {
+		const unflushed_count = frame.unflushed_instance_2d_count();
+
+		if (unflushed_count == 0) {
+			return;
+		}
+
+		sokol.gfx.applyPipeline(self.instance_2d_pipeline);
+
+		sokol.gfx.applyUniforms(.VS, Instance2D.shader.SLOT_Screen, sokol.gfx.asRange(&Instance2D.shader.Screen{
+			.screen_size = .{@floatFromInt(frame.width), @floatFromInt(frame.height)},
+		}));
+
+		const mesh_2d = self.objects.values[frame.mesh_2d.index().?].mesh_2d;
+		const texture = self.objects.values[frame.texture.index().?].texture;
+
+		var bindings = sokol.gfx.Bindings{
+			.vertex_buffers = get: {
+				var buffers = [_]sokol.gfx.Buffer{.{}} ** 8;
+
+				buffers[Instance2D.buffer_indices.mesh] = mesh_2d.vertex_buffer;
+
+				break: get buffers;
+			},
+
+			.index_buffer = mesh_2d.index_buffer,
+
+			.fs = .{
+				.images = get: {
+					var images = [_]sokol.gfx.Image{.{}} ** 12;
+
+					images[0] = texture.image;
+
+					break: get images;
+				},
+
+				.samplers = get: {
+					var samplers = [_]sokol.gfx.Sampler{.{}} ** 8;
+
+					samplers[0] = texture.sampler;
+
+					break: get samplers;
+				},
+			},
+		};
+
+		while (frame.flushed_instance_2d_count < frame.pushed_instance_2d_count) {
+			const buffer_index = frame.flushed_instance_2d_count / Instance2D.instances_per_buffer;
+			const buffer_offset = frame.flushed_instance_2d_count % Instance2D.instances_per_buffer;
+			const instances_to_flush = @min(Instance2D.instances_per_buffer - buffer_offset, unflushed_count);
+
+			bindings.vertex_buffers[Instance2D.buffer_indices.instance] = self.instance_2d_buffers.values[buffer_index];
+			bindings.vertex_buffer_offsets[Instance2D.buffer_indices.instance] = @intCast(buffer_offset);
+
+			sokol.gfx.applyBindings(bindings);
+			sokol.gfx.draw(0, mesh_2d.index_count, @intCast(instances_to_flush));
+
+			frame.flushed_instance_2d_count += instances_to_flush;
+		}
+	}
+
+	fn insert_object(self: *Rendering, index: usize, object: Object) !void {
+		const resource_count = self.objects.len();
+
+		if (index < resource_count) {
+			const empty_object = &self.objects.values[index];
+
+			if (empty_object.* != .empty) {
+				return error.InvalidHandle;
+			}
+
+			empty_object.* = object;
+		} else {
+			if (index != resource_count) {
+				return error.InvalidIndex;
+			}
+
+			try self.objects.push_grow(object);
+		}
+	}
+
+	fn push_instance_2d(self: *Rendering, frame: *Frame, command: RenderCommand.Instance) std.mem.Allocator.Error!void {
+		if (command.mesh_2d != frame.mesh_2d or command.texture != frame.texture) {
+			self.flush_instance_2ds(frame);
+		}
+
+		frame.mesh_2d = command.mesh_2d;
+		frame.texture = command.texture;
+
+		const has_filled_buffer = (frame.pushed_instance_2d_count % Instance2D.instances_per_buffer) == 0;
+		const pushed_buffer_count = frame.pushed_instance_2d_count / Instance2D.instances_per_buffer;
+
+		if (has_filled_buffer and pushed_buffer_count == self.instance_2d_buffers.len()) {
+			const instance_buffer = sokol.gfx.makeBuffer(.{
+				.size = @sizeOf(Instance2D) * Instance2D.instances_per_buffer,
+				.usage = .STREAM,
+				.label = "2D drawing instance buffer",
+			});
+
+			errdefer sokol.gfx.destroyBuffer(instance_buffer);
+
+			try self.instance_2d_buffers.push_grow(instance_buffer);
+		}
+
+		_ = sokol.gfx.appendBuffer(self.instance_2d_buffers.get().?, sokol.gfx.asRange(&Instance2D{
+			.transform = command.transform,
+		}));
+
+		frame.pushed_instance_2d_count += 1;
+	}
+
+	fn remove_object(self: *Rendering, index: usize) ?Object {
+		const object = self.objects.values[index];
+
+		if (object != .empty) {
+			self.objects.values[index] = .empty;
+
+			return object;
+		}
+
+		return null;
+	}
+};
+
+pub const RenderCommand = union (enum) {
+	instance_2d: Instance,
+	post_process: PostProcess,
+
+	pub const Instance = struct {
+		texture: gfx.Handle,
+		mesh_2d: gfx.Handle,
+		transform: gfx.Transform2D,
+	};
+
+	pub const PostProcess = struct {
+
+	};
+
+	fn clone(self: RenderCommand, arena: *std.heap.ArenaAllocator) std.mem.Allocator.Error!RenderCommand {
+		_ = arena;
+
+		return switch (self) {
+			.instance_2d => |instance_2d| .{.instance_2d = instance_2d},
+			.post_process => |post_process| .{.post_process = post_process},
+		};
+	}
+};
+
+pub const RenderChain = commands.Chain(RenderCommand, RenderCommand.clone);
+
+pub const RenderList = commands.List(RenderCommand, RenderCommand.clone);

src/ona/gfx/formats.zig

@@ -0,0 +1,77 @@
+const coral = @import("coral");
+
+const gfx = @import("../gfx.zig");
+
+const std = @import("std");
+
+pub fn bmp_file_desc(arena: *std.heap.ArenaAllocator, path: []const u8) gfx.Assets.Format.Error!gfx.Desc {
+	const header = try coral.files.bundle.read_little(path, 0, extern struct {
+		type: [2]u8 align (1),
+		file_size: u32 align (1),
+		reserved: [2]u16 align (1),
+		image_offset: u32 align (1),
+		header_size: u32 align (1),
+		pixel_width: i32 align (1),
+		pixel_height: i32 align (1),
+		color_planes: u16 align (1),
+		bits_per_pixel: u16 align (1),
+		compression_method: u32 align (1),
+		image_size: u32 align(1),
+		pixels_per_meter_x: i32 align (1),
+		pixels_per_meter_y: i32 align (1),
+		palette_colors_used: u32 align (1),
+		important_colors_used: u32 align (1),
+	}) orelse {
+		return error.FormatUnsupported;
+	};
+
+	if (!std.mem.eql(u8, &header.type, "BM")) {
+		return error.FormatUnsupported;
+	}
+
+	const pixel_width = std.math.cast(u16, header.pixel_width) orelse {
+		return error.FormatUnsupported;
+	};
+
+	const pixels = try arena.allocator().alloc(coral.io.Byte, header.image_size);
+	const bytes_per_pixel = header.bits_per_pixel / coral.io.bits_per_byte;
+	const alignment = 4;
+	const byte_stride = pixel_width * bytes_per_pixel;
+	const padded_byte_stride = alignment * @divTrunc((byte_stride + alignment - 1), alignment);
+	const byte_padding = coral.scalars.sub(padded_byte_stride, byte_stride) orelse 0;
+	var buffer_offset: usize = 0;
+	var file_offset = @as(usize, header.image_offset);
+
+	switch (header.bits_per_pixel) {
+		32 => {
+			while (buffer_offset < pixels.len) {
+				const line = pixels[buffer_offset .. buffer_offset + byte_stride];
+
+				if (try coral.files.bundle.read_bytes(path, file_offset, line) != byte_stride) {
+					return error.FormatUnsupported;
+				}
+
+				for (0 .. pixel_width) |i| {
+					const line_offset = i * 4;
+					const pixel = line[line_offset .. line_offset + 4];
+
+					std.mem.swap(u8, &pixel[0], &pixel[2]);
+				}
+
+				file_offset += line.len + byte_padding;
+				buffer_offset += padded_byte_stride;
+			}
+		},
+
+		else => return error.FormatUnsupported,
+	}
+
+	return .{
+		.texture = .{
+			.width = pixel_width,
+			.data = pixels,
+			.format = .rgba8,
+			.access = .static,
+		}
+	};
+}

src/ona/gfx/shaders/instance_2d.glsl

@@ -51,6 +51,10 @@ out vec4 texel;
 
 void main() {
 	texel = texture(sampler2D(tex, smp), uv) * color;
+
+	if (texel.a == 0) {
+		discard;
+	}
 }
 @end
 

src/ona/msg.zig

@@ -7,7 +7,7 @@ const std = @import("std");
 fn Channel(comptime Message: type) type {
 	return struct {
 		buffers: [2]coral.stack.Sequential(Message),
-		swapped: bool = false,
+		swap_index: u1 = 0,
 		ticks: u1 = 0,
 
 		const Self = @This();
@@ -28,9 +28,9 @@ fn Channel(comptime Message: type) type {
 			channel.res.ticks = coral.scalars.add(channel.res.ticks, 1) orelse 0;
 
 			if (channel.res.ticks == 0) {
-				channel.res.swapped = !channel.res.swapped;
+				channel.res.swap_index ^= 1;
 
-				channel.res.buffers[@intFromBool(channel.res.swapped)].clear();
+				channel.res.buffers[channel.res.swap_index].clear();
 			}
 		}
 
@@ -44,11 +44,11 @@ fn Channel(comptime Message: type) type {
 		}
 
 		fn messages(self: Self) []const Message {
-			return self.buffers[@intFromBool(!self.swapped)].values;
+			return self.buffers[self.swap_index ^ 1].values;
 		}
 
 		fn push(self: *Self, message: Message) std.mem.Allocator.Error!void {
-			try self.buffers[@intFromBool(self.swapped)].push(message);
+			try self.buffers[self.swap_index].push_grow(message);
 		}
 	};
 }