From a144d93b43fe4cb2b563d3b3c5517297d28b9bb8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Pa=CC=84vels=20Nadtoc=CC=8Cajevs?=
 <7645683+bruvzg@users.noreply.github.com>
Date: Sat, 8 Mar 2025 16:28:25 +0200
Subject: [PATCH] [macOS] Enable transparency for windows with decorations.

---
 platform/macos/display_server_macos.mm  | 30 ++++++++++++++++---------
 platform/macos/godot_window_delegate.mm |  4 +++-
 2 files changed, 22 insertions(+), 12 deletions(-)

diff --git a/platform/macos/display_server_macos.mm b/platform/macos/display_server_macos.mm
index a563318d4c..e6fbb1d5c0 100644
--- a/platform/macos/display_server_macos.mm
+++ b/platform/macos/display_server_macos.mm
@@ -265,9 +265,15 @@ void DisplayServerMacOS::set_window_per_pixel_transparency_enabled(bool p_enable
 		return;
 	}
 	if (p_enabled) {
-		[wd.window_object setBackgroundColor:[NSColor clearColor]];
 		[wd.window_object setOpaque:NO];
-		[wd.window_object setHasShadow:NO];
+		if (wd.borderless) {
+			[wd.window_object setBackgroundColor:[NSColor clearColor]];
+			[wd.window_object setHasShadow:NO];
+		} else {
+			// Note: transparent and not borderless - set alpha to non-zero value to ensure window shadow is rendered correctly.
+			[wd.window_object setBackgroundColor:[NSColor colorWithCalibratedRed:0 green:0 blue:0 alpha:0.004f]];
+			[wd.window_object setHasShadow:YES];
+		}
 		CALayer *layer = [(NSView *)wd.window_view layer];
 		if (layer) {
 			[layer setBackgroundColor:[NSColor clearColor].CGColor];
@@ -286,7 +292,9 @@ void DisplayServerMacOS::set_window_per_pixel_transparency_enabled(bool p_enable
 		}
 		[wd.window_object setBackgroundColor:bg_color];
 		[wd.window_object setOpaque:YES];
-		[wd.window_object setHasShadow:YES];
+		if (!wd.borderless) {
+			[wd.window_object setHasShadow:YES];
+		}
 		CALayer *layer = [(NSView *)wd.window_view layer];
 		if (layer) {
 			[layer setBackgroundColor:bg_color.CGColor];
@@ -2622,12 +2630,17 @@ void DisplayServerMacOS::window_set_flag(WindowFlags p_flag, bool p_enabled, Win
 			wd.borderless = p_enabled;
 			if (p_enabled) {
 				[wd.window_object setStyleMask:NSWindowStyleMaskBorderless];
-			} else {
+				[wd.window_object setHasShadow:NO];
 				if (wd.layered_window) {
-					wd.layered_window = false;
-					set_window_per_pixel_transparency_enabled(false, p_window);
+					[wd.window_object setBackgroundColor:[NSColor clearColor]];
 				}
+			} else {
 				[wd.window_object setStyleMask:NSWindowStyleMaskTitled | NSWindowStyleMaskClosable | NSWindowStyleMaskMiniaturizable | (wd.extend_to_title ? NSWindowStyleMaskFullSizeContentView : 0) | (wd.resize_disabled ? 0 : NSWindowStyleMaskResizable)];
+				[wd.window_object setHasShadow:YES];
+				if (wd.layered_window) {
+					// Note: transparent and not borderless - set alpha to non-zero value to ensure window shadow is rendered correctly.
+					[wd.window_object setBackgroundColor:[NSColor colorWithCalibratedRed:0 green:0 blue:0 alpha:0.004f]];
+				}
 				// Force update of the window styles.
 				NSRect frameRect = [wd.window_object frame];
 				[wd.window_object setFrame:NSMakeRect(frameRect.origin.x, frameRect.origin.y, frameRect.size.width + 1, frameRect.size.height) display:NO];
@@ -2659,11 +2672,6 @@ void DisplayServerMacOS::window_set_flag(WindowFlags p_flag, bool p_enabled, Win
 			if (wd.fullscreen) {
 				return;
 			}
-			if (p_enabled) {
-				[wd.window_object setStyleMask:NSWindowStyleMaskBorderless]; // Force borderless.
-			} else if (!wd.borderless) {
-				[wd.window_object setStyleMask:NSWindowStyleMaskTitled | NSWindowStyleMaskClosable | NSWindowStyleMaskMiniaturizable | (wd.extend_to_title ? NSWindowStyleMaskFullSizeContentView : 0) | (wd.resize_disabled ? 0 : NSWindowStyleMaskResizable)];
-			}
 			wd.layered_window = p_enabled;
 			set_window_per_pixel_transparency_enabled(p_enabled, p_window);
 			// Force update of the window styles.
diff --git a/platform/macos/godot_window_delegate.mm b/platform/macos/godot_window_delegate.mm
index 35c053dca5..7a8a085299 100644
--- a/platform/macos/godot_window_delegate.mm
+++ b/platform/macos/godot_window_delegate.mm
@@ -184,10 +184,12 @@
 	}
 
 	// Restore borderless, transparent and resizability state.
-	if (wd.borderless || wd.layered_window) {
+	if (wd.borderless) {
 		[wd.window_object setStyleMask:NSWindowStyleMaskBorderless];
+		[wd.window_object setHasShadow:NO];
 	} else {
 		[wd.window_object setStyleMask:NSWindowStyleMaskTitled | NSWindowStyleMaskClosable | NSWindowStyleMaskMiniaturizable | (wd.extend_to_title ? NSWindowStyleMaskFullSizeContentView : 0) | (wd.resize_disabled ? 0 : NSWindowStyleMaskResizable)];
+		[wd.window_object setHasShadow:YES];
 	}
 	if (wd.layered_window) {
 		ds->set_window_per_pixel_transparency_enabled(true, window_id);