wlbg: only do one frame per minute

F gpu

scripts/wlbg/build.zig

@@ -16,6 +16,10 @@ pub fn build(b: *std.Build) void {
         .optimize = optimize,
     });
 
+    exe.addModule("xev", b.dependency("xev", .{
+        .target = target,
+        .optimize = optimize,
+    }).module("xev"));
     exe.addModule("wayland", wayland_mod);
 
     scanner.addSystemProtocol("stable/xdg-shell/xdg-shell.xml");

scripts/wlbg/build.zig.zon

@@ -7,5 +7,9 @@
             .url = "https://git.mzte.de/LordMZTE/zig-wayland/archive/85722422985f928087e56d90c3617ecb04232486.tar.gz",
             .hash = "1220d992b223e473988d203d66d262e54141b59559c09587eb00231c800d46f9b408",
         },
+        .xev = .{
+            .url = "https://github.com/mitchellh/libxev/archive/5ecbc871f3bfa80fb7bf0fa853866cb93b99bc18.tar.gz",
+            .hash = "1220416854e424601ecc9814afb461a5dc9cf95db5917d82f794594a58ffc723b82c",
+        },
     },
 }

scripts/wlbg/src/Gfx.zig

@@ -7,7 +7,6 @@ const OutputInfo = @import("OutputInfo.zig");
 
 egl_dpy: c.EGLDisplay,
 bg_shader_program: c_uint,
-time: f64,
 
 const Gfx = @This();
 
@@ -31,7 +30,6 @@ pub fn init(egl_dpy: c.EGLDisplay) !Gfx {
     return .{
         .egl_dpy = egl_dpy,
         .bg_shader_program = program,
-        .time = 0.0,
     };
 }
 
@@ -40,15 +38,15 @@ pub fn deinit(self: *Gfx) void {
     self.* = undefined;
 }
 
-pub fn draw(
+pub fn drawBackground(
     self: *Gfx,
-    dt: f32,
+    dt: i64,
     egl_surface: c.EGLSurface,
     info: OutputInfo,
     base_xoff: i32,
     base_yoff: i32,
 ) !void {
-    self.time += dt;
+    _ = dt;
 
     // There's just about a 0% chance this works properly when monitors have different resolutions,
     // but I can't even begin thinking about that.
@@ -76,9 +74,11 @@ pub fn draw(
     c.glVertexAttribPointer(1, 2, c.GL_FLOAT, c.GL_FALSE, @sizeOf(f32) * 5, @ptrFromInt(@intFromPtr(&vertices) + @sizeOf(f32) * 3));
     c.glEnableVertexAttribArray(1);
 
-    c.glUniform1f(c.glGetUniformLocation(self.bg_shader_program, "time"), @as(f32, @floatCast(self.time / 10000.0)));
+    const rand = std.crypto.random.float(f32);
+    c.glUniform1f(c.glGetUniformLocation(self.bg_shader_program, "time"), rand * 2000.0 - 1000.0);
 
     c.glDrawArrays(c.GL_TRIANGLES, 0, vertices.len / 3);
 
-    if (c.eglSwapBuffers(self.egl_dpy, egl_surface) != c.EGL_TRUE) return error.EGLError;
+    if (c.eglSwapInterval(self.egl_dpy, 0) != c.EGL_TRUE or
+        c.eglSwapBuffers(self.egl_dpy, egl_surface) != c.EGL_TRUE) return error.EGLError;
 }

scripts/wlbg/src/main.zig

@@ -12,9 +12,11 @@ const wl = wayland.client.wl;
 const zwlr = wayland.client.zwlr;
 const zxdg = wayland.client.zxdg;
 
-const fps = 10;
-
 pub fn main() !void {
+    std.log.info("initializing event loop", .{});
+    var loop = try xev.Loop.init(.{});
+    defer loop.deinit();
+
     std.log.info("connecting to wayland display", .{});
     const dpy = try wl.Display.connect(null);
     defer dpy.disconnect();
@@ -146,32 +148,116 @@ pub fn main() !void {
     var gfx = try Gfx.init(egl_dpy);
     defer gfx.deinit();
 
-    var timer = try std.time.Timer.start();
-    var prev_time = std.time.milliTimestamp();
-    while (true) {
-        const now_time = std.time.milliTimestamp();
-        const delta_time: f32 = @floatFromInt(now_time - prev_time);
-        prev_time = now_time;
+    var rbgdata = RenderBackgroundData{
+        .gfx = &gfx,
+        .egl_dpy = egl_dpy,
+        .egl_ctx = egl_ctx,
+        .outputs = output_windows,
+        .output_info = output_info,
+        .last_time = loop.now(),
+        .base_offset = .{ base_xoff, base_yoff },
+    };
 
-        for (output_windows, output_info) |output, info| {
-            if (c.eglMakeCurrent(
-                egl_dpy,
-                output.egl_surface,
-                output.egl_surface,
-                egl_ctx,
-            ) != c.EGL_TRUE) return error.EGLError;
-            try gfx.draw(delta_time, output.egl_surface, info, base_xoff, base_yoff);
+    var rbg_timer_completion: xev.Completion = undefined;
+    var rbg_timer = try xev.Timer.init();
+    defer rbg_timer.deinit();
+
+    rbg_timer.run(
+        &loop,
+        &rbg_timer_completion,
+        0,
+        RenderBackgroundData,
+        &rbgdata,
+        renderBackgroundCb,
+    );
+
+    var wl_poll_completion = xev.Completion{
+        .op = .{ .poll = .{ .fd = dpy.getFd() } },
+        .userdata = dpy,
+        .callback = wlPollCb,
+    };
+    loop.add(&wl_poll_completion);
+
+    std.log.info("running event loop", .{});
+    try loop.run(.until_done);
+}
+
+const RenderBackgroundData = struct {
+    gfx: *Gfx,
+    egl_dpy: c.EGLDisplay,
+    egl_ctx: c.EGLContext,
+    outputs: []const OutputWindow,
+    output_info: []const OutputInfo,
+    last_time: isize,
+    base_offset: [2]c_int,
+};
+
+fn renderBackgroundCb(
+    data: ?*RenderBackgroundData,
+    loop: *xev.Loop,
+    completion: *xev.Completion,
+    result: xev.Timer.RunError!void,
+) xev.CallbackAction {
+    result catch unreachable;
+
+    const now = loop.now();
+
+    const delta_time = now - data.?.last_time;
+    data.?.last_time = now;
+    const next_time = now + std.time.ms_per_min;
+    completion.op.timer.reset = .{
+        .tv_sec = @divTrunc(next_time, std.time.ms_per_s),
+        .tv_nsec = @mod(next_time, std.time.ms_per_s) * std.time.ns_per_ms,
+    };
+
+    for (data.?.outputs, data.?.output_info) |output, info| {
+        if (c.eglMakeCurrent(
+            data.?.egl_dpy,
+            output.egl_surface,
+            output.egl_surface,
+            data.?.egl_ctx,
+        ) != c.EGL_TRUE) {
+            std.log.err("failed to set EGL context", .{});
+            loop.stop();
+            return .disarm;
         }
 
-        if (dpy.dispatchPending() != .SUCCESS or dpy.flush() != .SUCCESS) {
-            std.log.err("error processing wayland events", .{});
-            return error.DispatchFail;
-        }
-
-        const elapsed = timer.lap();
-        if (elapsed < 1000 * std.time.ns_per_ms / fps)
-            std.os.nanosleep(0, (1000 * std.time.ns_per_ms) / fps - elapsed);
+        data.?.gfx.drawBackground(
+            delta_time,
+            output.egl_surface,
+            info,
+            data.?.base_offset[0],
+            data.?.base_offset[1],
+        ) catch |e| {
+            std.log.err("drawing: {}", .{e});
+            loop.stop();
+            return .disarm;
+        };
     }
+
+    return .rearm;
+}
+
+fn wlPollCb(
+    userdata: ?*anyopaque,
+    loop: *xev.Loop,
+    _: *xev.Completion,
+    result: xev.Result,
+) xev.CallbackAction {
+    result.poll catch |e| {
+        std.log.err("unable to poll wayland FD: {}", .{e});
+        loop.stop();
+        return .disarm;
+    };
+
+    const dpy: *wl.Display = @ptrCast(@alignCast(userdata));
+    if (dpy.dispatchPending() != .SUCCESS or dpy.flush() != .SUCCESS) {
+        std.log.err("error processing wayland events", .{});
+        loop.stop();
+        return .disarm;
+    }
+
+    return .rearm;
 }
 
 const OutputWindow = struct {