From d87c8745597c6d107950cf222dc34554ad14d479 Mon Sep 17 00:00:00 2001
From: Jaime Passos <lazymyuutsu@gmail.com>
Date: Fri, 10 Jul 2020 19:19:51 -0300
Subject: [PATCH] Fix GL y-shearing ignoring a Y-flipped transform

---
 src/hardware/r_opengl/r_opengl.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/hardware/r_opengl/r_opengl.c b/src/hardware/r_opengl/r_opengl.c
index e5f6ff3cf..b7baa4eb0 100644
--- a/src/hardware/r_opengl/r_opengl.c
+++ b/src/hardware/r_opengl/r_opengl.c
@@ -2939,6 +2939,8 @@ EXPORT void HWRAPI(SetTransform) (FTransform *stransform)
 	if (shearing)
 	{
 		float fdy = stransform->viewaiming * 2;
+		if (stransform->flip)
+			fdy *= -1.0f;
 		pglTranslatef(0.0f, -fdy/BASEVIDHEIGHT, 0.0f);
 	}