From 74acd92d918485ae8c01d493505aac5b350ed5e0 Mon Sep 17 00:00:00 2001
From: myT <mighty.cow@mailinator.com>
Date: Tue, 18 Oct 2022 19:09:14 +0200
Subject: [PATCH] fixed the D3D projection transform not matching GL

---
 changelog.txt             | 2 ++
 code/renderer/tr_main.cpp | 9 +++++++--
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/changelog.txt b/changelog.txt
index 67e0880..731e67c 100644
--- a/changelog.txt
+++ b/changelog.txt
@@ -70,6 +70,8 @@ chg: with r_backend GL3, depth fade with MSAA now requires GLSL 4.00 at a minimu
 
 chg: with r_backend GL3, alpha to coverage now requires GLSL 4.00 at a minimum
 
+fix: the Direct3D projection transform didn't perfectly match the OpenGL version
+
 fix: /video was writing incorrect audio stream lengths to the .avi file headers
 
 fix: /systeminfo /serverinfo /clientinfo /dumpuser would crash when tokens were too long
diff --git a/code/renderer/tr_main.cpp b/code/renderer/tr_main.cpp
index 0e8ad6e..4496c4b 100644
--- a/code/renderer/tr_main.cpp
+++ b/code/renderer/tr_main.cpp
@@ -438,8 +438,13 @@ static void R_SetupProjection()
 
 	tr.viewParms.projectionMatrix[2] = 0;
 	tr.viewParms.projectionMatrix[6] = 0;
-	tr.viewParms.projectionMatrix[10] = -( zFar + zNear ) / depth;
-	tr.viewParms.projectionMatrix[14] = -2 * zFar * zNear / depth;
+	if ( gal.id == GAL_D3D11 ) {
+		tr.viewParms.projectionMatrix[10] = -zFar / depth;
+		tr.viewParms.projectionMatrix[14] = -zFar * zNear / depth;
+	} else {
+		tr.viewParms.projectionMatrix[10] = -( zFar + zNear ) / depth;
+		tr.viewParms.projectionMatrix[14] = -2 * zFar * zNear / depth;
+	}
 
 	tr.viewParms.projectionMatrix[3] = 0;
 	tr.viewParms.projectionMatrix[7] = 0;