From cf1f3103636b5221924c625145c2ddeb02833c27 Mon Sep 17 00:00:00 2001
From: Lactozilla <jp6781615@gmail.com>
Date: Fri, 25 Aug 2023 00:47:40 -0300
Subject: [PATCH] Add sector portals from visplanes while rendering a portal

---
 src/r_main.c   |  7 +++++--
 src/r_portal.c | 17 ++++++++++++-----
 src/r_portal.h |  4 +++-
 3 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/src/r_main.c b/src/r_main.c
index c73039c2a..c999b0f5e 100644
--- a/src/r_main.c
+++ b/src/r_main.c
@@ -1513,8 +1513,8 @@ void R_RenderPlayerView(player_t *player)
 	R_ClipSprites(drawsegs, NULL);
 	PS_STOP_TIMING(ps_sw_spritecliptime);
 
-	// Add skybox portals caused by sky visplanes.
-	Portal_AddSkyboxPortals();
+	// Add portals caused by visplanes.
+	Portal_AddPlanePortals(cv_skybox.value);
 
 	// Portal rendering. Hijacks the BSP traversal.
 	PS_START_TIMING(ps_sw_portaltime);
@@ -1559,6 +1559,9 @@ void R_RenderPlayerView(player_t *player)
 				R_RenderBSPNode((INT32)numnodes - 1);
 			}
 
+			// Don't add skybox portals while IN a skybox portal, because that'll cause infinite recursion
+			Portal_AddPlanePortals(!portal->is_skybox);
+
 			Mask_Post(&masks[nummasks - 1]);
 
 			R_ClipSprites(ds_p - (masks[nummasks - 1].drawsegs[1] - masks[nummasks - 1].drawsegs[0]), portal);
diff --git a/src/r_portal.c b/src/r_portal.c
index bb40b2c80..ffa5d1a0d 100644
--- a/src/r_portal.c
+++ b/src/r_portal.c
@@ -192,6 +192,7 @@ void Portal_Add2Lines (const INT32 line1, const INT32 line2, const INT32 x1, con
 	Portal_GetViewpointForLine(portal, start, dest);
 
 	portal->clipline = line2;
+	portal->is_skybox = false;
 	portal->is_horizon = false;
 	portal->horizon_sector = NULL;
 
@@ -317,6 +318,7 @@ void Portal_AddSkybox (const visplane_t* plane)
 	Portal_ClipVisplane(plane, portal);
 
 	portal->clipline = -1;
+	portal->is_skybox = true;
 	portal->is_horizon = false;
 	portal->horizon_sector = NULL;
 
@@ -396,7 +398,8 @@ void Portal_AddSectorPortal (const visplane_t* plane)
 	// Shortcut
 	if (secportal->type == SECPORTAL_SKYBOX)
 	{
-		Portal_AddSkybox(plane);
+		if (skyboxmo[0])
+			Portal_AddSkybox(plane);
 		return;
 	}
 
@@ -409,6 +412,7 @@ void Portal_AddSectorPortal (const visplane_t* plane)
 
 	portal->clipline = -1;
 	portal->is_horizon = false;
+	portal->is_skybox = false;
 	portal->horizon_sector = NULL;
 
 	Portal_GetViewpointForSecPortal(portal, secportal);
@@ -426,7 +430,7 @@ void Portal_AddTransferred (UINT32 secportalnum, const INT32 x1, const INT32 x2)
 		return;
 
 	portal_t* portal = Portal_Add(x1, x2);
-
+	portal->is_skybox = false;
 	portal->is_horizon = false;
 	portal->horizon_sector = NULL;
 
@@ -445,10 +449,10 @@ void Portal_AddTransferred (UINT32 secportalnum, const INT32 x1, const INT32 x2)
 	portalline = true;
 }
 
-/** Creates portals for the currently existing sky visplanes.
+/** Creates portals for the currently existing portal visplanes.
  * The visplanes are also removed and cleared from the list.
  */
-void Portal_AddSkyboxPortals (void)
+void Portal_AddPlanePortals (boolean add_skyboxes)
 {
 	visplane_t *pl;
 
@@ -456,6 +460,9 @@ void Portal_AddSkyboxPortals (void)
 	{
 		for (pl = visplanes[i]; pl; pl = pl->next)
 		{
+			if (pl->minx >= pl->maxx)
+				continue;
+
 			boolean added_portal = false;
 
 			// Render sector portal if recursiveness limit hasn't been reached
@@ -466,7 +473,7 @@ void Portal_AddSkyboxPortals (void)
 			}
 
 			// Render skybox portal
-			if (!added_portal && pl->picnum == skyflatnum && cv_skybox.value && skyboxmo[0])
+			if (!added_portal && pl->picnum == skyflatnum && add_skyboxes && skyboxmo[0])
 			{
 				Portal_AddSkybox(pl);
 				added_portal = true;
diff --git a/src/r_portal.h b/src/r_portal.h
index 69ecb8d7f..b3c4b0edc 100644
--- a/src/r_portal.h
+++ b/src/r_portal.h
@@ -34,6 +34,8 @@ typedef struct portal_s
 	boolean is_horizon;
 	sector_t *horizon_sector;
 
+	boolean is_skybox;
+
 	UINT8 pass;			/**< Keeps track of the portal's recursion depth. */
 	INT32 clipline;		/**< Optional clipline for line-based portals. */
 
@@ -63,5 +65,5 @@ void Portal_AddTransferred	(UINT32 secportalnum, const INT32 x1, const INT32 x2)
 void Portal_ClipRange (portal_t* portal);
 void Portal_ClipApply (const portal_t* portal);
 
-void Portal_AddSkyboxPortals (void);
+void Portal_AddPlanePortals (boolean add_skyboxes);
 #endif