Core: add .present_frame event replacing swapbuffers call

Note that on e.g. web platform, swapbuffers is not an explicit call.
We also need a signal that the frame has been submitted and finished,
and this is it.

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>

examples/core-custom-entrypoint/Game.zig

@@ -104,7 +104,7 @@ fn tick(core: *mach.Core.Mod, game: *Mod) !void {
     core.state().queue.submit(&[_]*gpu.CommandBuffer{command});
 
     // Present the frame
-    mach.core.swap_chain.present();
+    core.send(.present_frame, .{});
 
     // update the window title every second
     if (game.state().title_timer.read() >= 1.0) {

examples/custom-renderer/Game.zig

@@ -47,10 +47,6 @@ fn init(
     renderer: *Renderer.Mod,
     game: *Mod,
 ) !void {
-    // The Mach .core is where we set window options, etc.
-    // TODO(important): replace this API with something better
-    mach.core.setTitle("Hello, ECS!");
-
     // Create our player entity.
     const player = try core.newEntity();
 

examples/custom-renderer/Renderer.zig

@@ -123,22 +123,29 @@ fn tick(
     renderer: *Mod,
 ) !void {
     const device = core.state().device;
+    _ = device; // autofix
 
-    // Begin our render pass
+    // Grab the back buffer of the swapchain
     const back_buffer_view = mach.core.swap_chain.getCurrentTextureView().?;
-    const color_attachment = gpu.RenderPassColorAttachment{
+    defer back_buffer_view.release();
+
+    // Create a command encoder
+    const label = @tagName(name) ++ ".tick";
+    const encoder = core.state().device.createCommandEncoder(&.{ .label = label });
+    defer encoder.release();
+
+    // Begin render pass
+    const sky_blue_background = gpu.Color{ .r = 0.776, .g = 0.988, .b = 1, .a = 1 };
+    const color_attachments = [_]gpu.RenderPassColorAttachment{.{
         .view = back_buffer_view,
-        .clear_value = std.mem.zeroes(gpu.Color),
+        .clear_value = sky_blue_background,
         .load_op = .clear,
         .store_op = .store,
-    };
-
-    const label = @tagName(name) ++ ".tick";
-    const encoder = device.createCommandEncoder(&.{ .label = label });
-    const render_pass_info = gpu.RenderPassDescriptor.init(.{
+    }};
+    const render_pass = encoder.beginRenderPass(&gpu.RenderPassDescriptor.init(.{
         .label = label,
-        .color_attachments = &.{color_attachment},
-    });
+        .color_attachments = &color_attachments,
+    }));
 
     // Update uniform buffer
     var archetypes_iter = core.entities.query(.{ .all = &.{
@@ -161,20 +168,21 @@ fn tick(
         }
     }
 
-    const pass = encoder.beginRenderPass(&render_pass_info);
+    // Draw
     for (renderer.state().bind_groups[0..num_entities]) |bind_group| {
-        pass.setPipeline(renderer.state().pipeline);
-        pass.setBindGroup(0, bind_group, &.{0});
-        pass.draw(3, 1, 0, 0);
+        render_pass.setPipeline(renderer.state().pipeline);
+        render_pass.setBindGroup(0, bind_group, &.{0});
+        render_pass.draw(3, 1, 0, 0);
     }
-    pass.end();
-    pass.release();
 
+    // Finish render pass
+    render_pass.end();
+
+    // Submit our commands to the queue
     var command = encoder.finish(&.{ .label = label });
-    encoder.release();
+    defer command.release();
+    core.state().queue.submit(&[_]*gpu.CommandBuffer{command});
 
-    renderer.state().queue.submit(&[_]*gpu.CommandBuffer{command});
-    command.release();
-    mach.core.swap_chain.present();
-    back_buffer_view.release();
+    // Present the frame
+    core.send(.present_frame, .{});
 }

examples/glyphs/Game.zig

@@ -238,7 +238,7 @@ fn endFrame(game: *Mod, core: *mach.Core.Mod) !void {
     core.state().queue.submit(&[_]*gpu.CommandBuffer{command});
 
     // Present the frame
-    mach.core.swap_chain.present();
+    core.send(.present_frame, .{});
 
     // Every second, update the window title with the FPS
     if (game.state().fps_timer.read() >= 1.0) {

examples/piano/Piano.zig

@@ -12,6 +12,7 @@ const std = @import("std");
 const builtin = @import("builtin");
 
 const mach = @import("mach");
+const gpu = mach.gpu;
 const math = mach.math;
 const sysaudio = mach.sysaudio;
 
@@ -109,10 +110,40 @@ fn tick(
         }
     }
 
+    // Grab the back buffer of the swapchain
     const back_buffer_view = mach.core.swap_chain.getCurrentTextureView().?;
+    defer back_buffer_view.release();
 
-    mach.core.swap_chain.present();
-    back_buffer_view.release();
+    // Create a command encoder
+    const label = @tagName(name) ++ ".tick";
+    const encoder = core.state().device.createCommandEncoder(&.{ .label = label });
+    defer encoder.release();
+
+    // Begin render pass
+    const sky_blue_background = gpu.Color{ .r = 0.776, .g = 0.988, .b = 1, .a = 1 };
+    const color_attachments = [_]gpu.RenderPassColorAttachment{.{
+        .view = back_buffer_view,
+        .clear_value = sky_blue_background,
+        .load_op = .clear,
+        .store_op = .store,
+    }};
+    const render_pass = encoder.beginRenderPass(&gpu.RenderPassDescriptor.init(.{
+        .label = label,
+        .color_attachments = &color_attachments,
+    }));
+
+    // Draw nothing
+
+    // Finish render pass
+    render_pass.end();
+
+    // Submit our commands to the queue
+    var command = encoder.finish(&.{ .label = label });
+    defer command.release();
+    core.state().queue.submit(&[_]*gpu.CommandBuffer{command});
+
+    // Present the frame
+    core.send(.present_frame, .{});
 }
 
 fn fillTone(audio: *mach.Audio.Mod, frequency: f32) ![]const f32 {

examples/sprite/Game.zig

@@ -222,7 +222,7 @@ fn endFrame(game: *Mod, core: *mach.Core.Mod) !void {
     core.state().queue.submit(&[_]*gpu.CommandBuffer{command});
 
     // Present the frame
-    mach.core.swap_chain.present();
+    core.send(.present_frame, .{});
 
     // Every second, update the window title with the FPS
     if (game.state().fps_timer.read() >= 1.0) {

examples/text/Game.zig

@@ -63,9 +63,6 @@ fn init(
     text_style: *gfx.TextStyle.Mod,
     game: *Mod,
 ) !void {
-    // The Mach .core is where we set window options, etc.
-    mach.core.setTitle("gfx.Text example");
-
     // TODO: a better way to initialize entities with default values
     // TODO(text): most of these style options are not respected yet.
     const style1 = try core.newEntity();
@@ -268,7 +265,7 @@ fn endFrame(game: *Mod, text: *gfx.Text.Mod, core: *mach.Core.Mod) !void {
     core.state().queue.submit(&[_]*gpu.CommandBuffer{command});
 
     // Present the frame
-    mach.core.swap_chain.present();
+    core.send(.present_frame, .{});
 
     // Every second, update the window title with the FPS
     if (game.state().fps_timer.read() >= 1.0) {

src/Core.zig

@@ -19,6 +19,10 @@ pub const local_events = .{
     \\ Send this when window entities have been updated and you want the new values respected.
     },
 
+    .present_frame = .{ .handler = presentFrame, .description = 
+    \\ Send this when rendering has finished and the swapchain should be presented.
+    },
+
     .init = .{ .handler = init },
     .init_done = .{ .handler = fn () void },
 
@@ -49,7 +53,7 @@ pub const components = .{
 /// try mach.Core.printTitle(core_mod, core_mod.state().main_window, "Hello, {s}!", .{"Mach"});
 /// ```
 pub fn printTitle(
-    core: *mach.Core.Mod,
+    core: *Mod,
     window_id: mach.EntityID,
     comptime fmt: []const u8,
     args: anytype,
@@ -106,6 +110,13 @@ fn update(core: *Mod) !void {
     if (num_windows > 1) @panic("mach: Core currently only supports a single window");
 }
 
+fn presentFrame(core: *Mod) !void {
+    mach.core.swap_chain.present();
+
+    // Signal that mainThreadTick is done
+    core.send(.main_thread_tick_done, .{});
+}
+
 fn deinit(core: *Mod) void {
     core.state().queue.release();
     // TODO: this triggers a device loss error, which we should handle correctly
@@ -129,9 +140,6 @@ fn mainThreadTick(core: *Mod) !void {
 
     // Send .tick to anyone interested
     core.sendGlobal(.tick, .{});
-
-    // Signal that mainThreadTick is done
-    core.send(.main_thread_tick_done, .{});
 }
 
 fn exit(core: *Mod) void {

src/module/module.zig

@@ -342,6 +342,7 @@ pub fn Modules(comptime modules: anytype) type {
             options: DispatchOptions,
             injectable: anytype,
         ) !void {
+            @setEvalBranchQuota(10000);
             // TODO: optimize to reduce send contention
             // TODO: parallel / multi-threaded dispatch
             // TODO: PGO