From 099e25824fcb3cbda74256e0d16e0255475b0176 Mon Sep 17 00:00:00 2001
From: Monster Iestyn <iestynjealous@ntlworld.com>
Date: Sat, 5 Mar 2016 16:29:25 +0000
Subject: [PATCH] First person view now should correctly take the skybox
 centerpoint's angle into account

---
 src/r_main.c | 36 ++++++++++++++++++++++++++++++++----
 1 file changed, 32 insertions(+), 4 deletions(-)

diff --git a/src/r_main.c b/src/r_main.c
index a4e72cba9..b1a2036cc 100644
--- a/src/r_main.c
+++ b/src/r_main.c
@@ -972,14 +972,42 @@ void R_SkyboxFrame(player_t *player)
 		{
 			if (skyboxmo[1])
 			{
+				fixed_t x = 0, y = 0;
 				if (mh->skybox_scalex > 0)
-					viewx += (player->mo->x - skyboxmo[1]->x) / mh->skybox_scalex;
+					x = (player->mo->x - skyboxmo[1]->x) / mh->skybox_scalex;
 				else if (mh->skybox_scalex < 0)
-					viewx += (player->mo->x - skyboxmo[1]->x) * -mh->skybox_scalex;
+					x = (player->mo->x - skyboxmo[1]->x) * -mh->skybox_scalex;
 				if (mh->skybox_scaley > 0)
-					viewy += (player->mo->y - skyboxmo[1]->y) / mh->skybox_scaley;
+					y = (player->mo->y - skyboxmo[1]->y) / mh->skybox_scaley;
 				else if (mh->skybox_scaley < 0)
-					viewy += (player->mo->y - skyboxmo[1]->y) * -mh->skybox_scaley;
+					y = (player->mo->y - skyboxmo[1]->y) * -mh->skybox_scaley;
+
+				if (viewmobj->angle == 0)
+				{
+					viewx += x;
+					viewy += y;
+				}
+				else if (viewmobj->angle == ANGLE_90)
+				{
+					viewx -= y;
+					viewy += x;
+				}
+				else if (viewmobj->angle == ANGLE_180)
+				{
+					viewx -= x;
+					viewy -= y;
+				}
+				else if (viewmobj->angle == ANGLE_270)
+				{
+					viewx += y;
+					viewy -= x;
+				}
+				else
+				{
+					angle_t ang = viewmobj->angle>>ANGLETOFINESHIFT;
+					viewx += FixedMul(x,FINECOSINE(ang)) - FixedMul(y,  FINESINE(ang));
+					viewy += FixedMul(x,  FINESINE(ang)) + FixedMul(y,FINECOSINE(ang));
+				}
 			}
 			if (mh->skybox_scalez > 0)
 				viewz += player->viewz / mh->skybox_scalez;