From 84df44d344cf2a2713fcf01196da8852a72e1bc9 Mon Sep 17 00:00:00 2001
From: 23rd <23rd@vivaldi.net>
Date: Thu, 23 Apr 2026 23:25:26 +0300
Subject: [PATCH] Fixed upside-down webcam in group calls on Linux QRhi path.

---
 .../calls/group/calls_group_viewport_rhi.cpp         | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/Telegram/SourceFiles/calls/group/calls_group_viewport_rhi.cpp b/Telegram/SourceFiles/calls/group/calls_group_viewport_rhi.cpp
index ecb32041f8..31696f3fad 100644
--- a/Telegram/SourceFiles/calls/group/calls_group_viewport_rhi.cpp
+++ b/Telegram/SourceFiles/calls/group/calls_group_viewport_rhi.cpp
@@ -952,12 +952,24 @@ void Viewport::RendererRhi::drawYuv2RgbPass(
 		tileData.convertedSize = frameSize;
 	}
 
+	// Y-flip the UV for Linux: QRhi/OpenGL on Linux lands YUV frames
+	// upside-down in the offscreen RGB target compared with Metal/D3D11
+	// backends used on macOS/Windows, which already render correctly.
+#ifdef Q_OS_LINUX
+	const float coords[] = {
+		-1.f, -1.f, 0.f, 0.f,
+		 1.f, -1.f, 1.f, 0.f,
+		-1.f,  1.f, 0.f, 1.f,
+		 1.f,  1.f, 1.f, 1.f,
+	};
+#else // Q_OS_LINUX
 	const float coords[] = {
 		-1.f, -1.f, 0.f, 1.f,
 		 1.f, -1.f, 1.f, 1.f,
 		-1.f,  1.f, 0.f, 0.f,
 		 1.f,  1.f, 1.f, 0.f,
 	};
+#endif // Q_OS_LINUX
 
 	if (!_rub) {
 		_rub = _rhi->nextResourceUpdateBatch();