diff --git a/src/nu.zig b/src/nu.zig
index 759e098..26be0d6 100644
--- a/src/nu.zig
+++ b/src/nu.zig
@@ -22,8 +22,16 @@ pub fn run(
         _ = events;
 
         inline for (modules) |module| {
-            if (@hasDecl(module, "frame"))
-                module.frame();
+            if (@hasDecl(module, "frame")) {
+                if (@typeInfo(@TypeOf(module.frame)).Fn.return_type) |R| {
+                    switch (@typeInfo(R)) {
+                        .ErrorUnion => try module.frame(),
+                        else => @compileError("frame must be void or !void."),
+                    }
+                } else {
+                    module.frame();
+                }
+            }
         }
 
         // todo fixed timestep
diff --git a/src/nu/Render.zig b/src/nu/Render.zig
index 972f4e8..43dc9f0 100644
--- a/src/nu/Render.zig
+++ b/src/nu/Render.zig
@@ -6,6 +6,7 @@ const std = @import("std");
 const builtin = @import("builtin");
 const vk = @import("vk");
 
+const nu = @import("../nu.zig");
 const au = @import("Render/au.zig");
 
 pub const Options = struct {
@@ -26,15 +27,79 @@ pub const Options = struct {
     frames_in_flight: u8 = 3,
 };
 
-pub fn init(alloc: std.mem.Allocator) !void {
-    // todo make ctx not globals
+var sc: au.SwapChain = undefined;
+var flights: au.Flights = undefined;
 
+pub fn init(alloc: std.mem.Allocator) !void {
+    // todo pick apart au into helpers; not a sub-module filled with its own globals.
     try au.init(alloc);
     errdefer au.deinit();
+
+    sc = try au.SwapChain.init(alloc);
+    errdefer sc.deinit();
+
+    flights = try au.Flights.init(alloc, nu.options.render.frames_in_flight);
+    errdefer flights.deinit();
 }
 
-pub fn frame() void {}
+pub fn frame() !void {
+    const flight: au.Flights.Flight = flights.next();
+    try flight.wait();
+
+    while (true) {
+        _ = try sc.rebuild();
+
+        const target = sc.acquire(flight.acquire, .null_handle) catch |err| switch (err) {
+            error.OutOfDateKHR => {
+                sc.mark();
+                continue;
+            },
+            else => return err,
+        };
+
+        const render_area: vk.Rect2D = .{
+            .offset = .{ .x = 0, .y = 0 },
+            .extent = sc.cinfo.image_extent,
+        };
+
+        try au.D.resetCommandPool(flight.pool, .{});
+        var cmd = au.CommandBufferProxy.init(flight.cmd, au.D.wrapper);
+
+        try cmd.beginCommandBuffer(&.{ .flags = .{ .one_time_submit_bit = true } });
+        target.begin_rendering(cmd, render_area);
+        target.end_rendering(cmd);
+        try cmd.endCommandBuffer();
+
+        try au.Q.submit(1, &.{
+            vk.SubmitInfo{
+                .wait_semaphore_count = 1,
+                .p_wait_semaphores = &.{flight.acquire},
+                .p_wait_dst_stage_mask = &.{
+                    vk.PipelineStageFlags{ .color_attachment_output_bit = true },
+                },
+                .command_buffer_count = 1,
+                .p_command_buffers = &.{cmd.handle},
+                .signal_semaphore_count = 1,
+                .p_signal_semaphores = &.{flight.complete},
+            },
+        }, flight.fence);
+
+        if (sc.present(&.{flight.complete}, target)) |_| {
+            return;
+        } else |err| switch (err) {
+            error.OutOfDateKHR => {
+                try flight.wait();
+                sc.mark();
+                continue;
+            },
+            else => return err,
+        }
+    }
+}
 
 pub fn deinit() void {
+    au.D.deviceWaitIdle() catch {};
+    flights.deinit();
+    sc.deinit();
     au.deinit();
 }
diff --git a/src/nu/Render/au/Flights.zig b/src/nu/Render/au/Flights.zig
index d758170..4662e08 100644
--- a/src/nu/Render/au/Flights.zig
+++ b/src/nu/Render/au/Flights.zig
@@ -4,12 +4,17 @@ const au = @import("../au.zig");
 
 const Self = @This();
 
-const Flight = struct {
+pub const Flight = struct {
     acquire: vk.Semaphore = .null_handle,
     complete: vk.Semaphore = .null_handle,
     fence: vk.Fence = .null_handle,
     pool: vk.CommandPool = .null_handle,
     cmd: vk.CommandBuffer = .null_handle,
+
+    pub fn wait(self: Flight) !void {
+        _ = try au.D.waitForFences(1, &.{self.fence}, vk.TRUE, std.math.maxInt(u64));
+        try au.D.resetFences(1, &.{self.fence});
+    }
 };
 
 alloc: std.mem.Allocator,
diff --git a/src/nu/Render/au/SwapChain.zig b/src/nu/Render/au/SwapChain.zig
index 77a28a9..204316d 100644
--- a/src/nu/Render/au/SwapChain.zig
+++ b/src/nu/Render/au/SwapChain.zig
@@ -11,7 +11,7 @@ images: std.ArrayListUnmanaged(vk.Image) = .{},
 views: std.ArrayListUnmanaged(vk.ImageView) = .{},
 
 pub fn init(alloc: std.mem.Allocator) !Self {
-    const caps = try au.I.getPhysicalDeviceSurfaceCapabilitiesKHR(au.device_config.pdev, au.W.surface);
+    const caps = try au.I.getPhysicalDeviceSurfaceCapabilitiesKHR(au.device_config.pdev, au.S.*);
 
     var min_image_count = @max(3, caps.min_image_count + 1); // todo magic numbers
     if (caps.max_image_count > 0) {
@@ -24,7 +24,7 @@ pub fn init(alloc: std.mem.Allocator) !Self {
     return .{
         .alloc = alloc,
         .cinfo = .{
-            .surface = au.W.surface,
+            .surface = au.S.*,
             .min_image_count = min_image_count,
             .image_format = format.format,
             .image_color_space = format.color_space,