From 5603b7b841055ee3298453456317f209d9b0cbef Mon Sep 17 00:00:00 2001
From: James R <justsomejames2@gmail.com>
Date: Wed, 17 Jan 2024 16:43:45 -0800
Subject: [PATCH] debugrender_freezebsp: freeze culling to your current
 position, so you can see how much level is being rendered

---
 src/cvars.cpp  |  1 +
 src/r_bsp.cpp  | 49 +++++++++++++++++++++++++++++++++++++++++++++++--
 src/r_bsp.h    |  1 +
 src/r_main.cpp |  8 ++++----
 4 files changed, 53 insertions(+), 6 deletions(-)

diff --git a/src/cvars.cpp b/src/cvars.cpp
index b16d04987..d8001f007 100644
--- a/src/cvars.cpp
+++ b/src/cvars.cpp
@@ -876,6 +876,7 @@ consvar_t cv_debugrank = PlayerCheat("debugrank", "Off").description("Show GP ra
 });
 
 consvar_t cv_debugrender_contrast = PlayerCheat("debugrender_contrast", "0.0").floating_point().min_max(-FRACUNIT, FRACUNIT).description("Change level lighting");
+consvar_t cv_debugrender_freezebsp = PlayerCheat("debugrender_freezebsp", "Off").on_off().description("Freeze level culling so you can observe how much of the level is being rendered");
 consvar_t cv_debugrender_portal = PlayerCheat("debugrender_portal", "Off").on_off().description("Highlight visual portals in red");
 consvar_t cv_debugrender_spriteclip = PlayerCheat("debugrender_spriteclip", "Off").on_off().description("Let sprites draw through walls");
 consvar_t cv_debugrender_visplanes = PlayerCheat("debugrender_visplanes", "Off").on_off().description("Highlight the number of visplanes");
diff --git a/src/r_bsp.cpp b/src/r_bsp.cpp
index e6a7c011a..736037dac 100644
--- a/src/r_bsp.cpp
+++ b/src/r_bsp.cpp
@@ -12,6 +12,7 @@
 /// \brief BSP traversal, handling of LineSegs for rendering
 
 #include <algorithm>
+#include <vector>
 
 #include <tracy/tracy/Tracy.hpp>
 
@@ -31,7 +32,7 @@
 
 #include "k_terrain.h"
 
-extern "C" consvar_t cv_debugfinishline;
+extern "C" consvar_t cv_debugfinishline, cv_debugrender_freezebsp;
 
 seg_t *curline;
 side_t *sidedef;
@@ -53,6 +54,9 @@ INT32 doorclosed;
 // can block off the BSP across that seg.
 boolean g_walloffscreen;
 
+static std::vector<std::vector<INT32>> node_cache;
+static std::vector<INT32>* current_node_cache;
+
 boolean R_NoEncore(sector_t *sector, levelflat_t *flat, boolean ceiling)
 {
 	const boolean invertEncore = (sector->flags & MSF_INVERTENCORE);
@@ -1420,5 +1424,46 @@ void R_RenderBSPNode(INT32 bspnum)
 		portalcullsector = NULL;
 	}
 
-	R_Subsector(bspnum == -1 ? 0 : bspnum & ~NF_SUBSECTOR);
+	bspnum = (bspnum == -1 ? 0 : bspnum & ~NF_SUBSECTOR);
+	R_Subsector(bspnum);
+
+	if (current_node_cache)
+	{
+		current_node_cache->push_back(bspnum);
+	}
+}
+
+static bool render_cache(size_t cachenum)
+{
+	if (node_cache.empty() && !cv_debugrender_freezebsp.value)
+	{
+		current_node_cache = nullptr;
+		return false;
+	}
+
+	if (!cv_debugrender_freezebsp.value)
+	{
+		// free cache
+		node_cache = {};
+		current_node_cache = nullptr;
+		return false;
+	}
+
+	if (node_cache.size() <= cachenum)
+	{
+		node_cache.resize(cachenum + 1);
+		current_node_cache = &node_cache[cachenum];
+		return false;
+	}
+
+	for (INT32 bspnum : node_cache[cachenum])
+		R_Subsector(bspnum);
+
+	return true;
+}
+
+void R_RenderFirstBSPNode(size_t cachenum)
+{
+	if (!render_cache(cachenum))
+		R_RenderBSPNode((INT32)numnodes - 1);
 }
diff --git a/src/r_bsp.h b/src/r_bsp.h
index 5002a4d8a..17407f5e6 100644
--- a/src/r_bsp.h
+++ b/src/r_bsp.h
@@ -42,6 +42,7 @@ void R_ClearClipSegs(void);
 void R_PortalClearClipSegs(INT32 start, INT32 end);
 void R_ClearDrawSegs(void);
 void R_RenderBSPNode(INT32 bspnum);
+void R_RenderFirstBSPNode(size_t cachenum);
 
 // determines when a given sector shouldn't abide by the encoremap's palette.
 // no longer a static since this is used for encore in hw_main.c as well now:
diff --git a/src/r_main.cpp b/src/r_main.cpp
index 2649fb3a1..365bd6674 100644
--- a/src/r_main.cpp
+++ b/src/r_main.cpp
@@ -1456,13 +1456,13 @@ static void Mask_Post (maskcount_t* m)
 // ================
 
 // viewx, viewy, viewangle, all that good stuff must be set
-static void R_RenderViewpoint(maskcount_t* mask)
+static void R_RenderViewpoint(maskcount_t* mask, INT32 cachenum)
 {
 	Mask_Pre(mask);
 
 	curdrawsegs = ds_p;
 
-	R_RenderBSPNode((INT32)numnodes - 1);
+	R_RenderFirstBSPNode(cachenum);
 	R_AddPrecipitationSprites();
 
 	Mask_Post(mask);
@@ -1518,7 +1518,7 @@ void R_RenderPlayerView(void)
 
 	srb2::ThreadPool::Sema tp_sema;
 	srb2::g_main_threadpool->begin_sema();
-	R_RenderViewpoint(&masks[nummasks - 1]);
+	R_RenderViewpoint(&masks[nummasks - 1], nummasks - 1);
 
 	ps_bsptime = I_GetPreciseTime() - ps_bsptime;
 #ifdef TIMING
@@ -1576,7 +1576,7 @@ void R_RenderPlayerView(void)
 			// Render the BSP from the new viewpoint, and clip
 			// any sprites with the new clipsegs and window.
 
-			R_RenderViewpoint(&masks[nummasks - 1]);
+			R_RenderViewpoint(&masks[nummasks - 1], nummasks - 1);
 
 			portalskipprecipmobjs = false;