From 14f9c63cd714c9cc06f7be5be34a04862bd63fee Mon Sep 17 00:00:00 2001
From: Magnus Norddahl <dpjudas@users.noreply.github.com>
Date: Tue, 8 May 2018 22:22:15 +0200
Subject: [PATCH] - added r_debug_draw that shows how the software renderer
 composes its scene

(cherry picked from commit 459f748c4e34bfa35f132bfaaa610b74ca9964bb)
---
 src/swrenderer/drawers/r_thread.cpp | 34 +++++++++++++++++++++++++++--
 src/swrenderer/drawers/r_thread.h   |  6 +++++
 src/swrenderer/scene/r_scene.cpp    |  4 +++-
 3 files changed, 41 insertions(+), 3 deletions(-)

diff --git a/src/swrenderer/drawers/r_thread.cpp b/src/swrenderer/drawers/r_thread.cpp
index 57d86ab9b..32e73683a 100644
--- a/src/swrenderer/drawers/r_thread.cpp
+++ b/src/swrenderer/drawers/r_thread.cpp
@@ -40,6 +40,7 @@ void PeekThreadedErrorPane();
 #endif
 
 CVAR(Bool, r_multithreaded, true, CVAR_ARCHIVE | CVAR_GLOBALCONFIG);
+CVAR(Int, r_debug_draw, 0, 0);
 
 /////////////////////////////////////////////////////////////////////////////
 
@@ -76,6 +77,23 @@ void DrawerThreads::Execute(DrawerCommandQueuePtr commands)
 	queue->start_condition.notify_all();
 }
 
+void DrawerThreads::ResetDebugDrawPos()
+{
+	auto queue = Instance();
+	std::unique_lock<std::mutex> start_lock(queue->start_mutex);
+	bool reached_end = false;
+	for (auto &thread : queue->threads)
+	{
+		if (thread.debug_draw_pos + r_debug_draw * 60 * 2 < queue->debug_draw_end)
+			reached_end = true;
+		thread.debug_draw_pos = 0;
+	}
+	if (!reached_end)
+		queue->debug_draw_end += r_debug_draw;
+	else
+		queue->debug_draw_end = 0;
+}
+
 void DrawerThreads::WaitForWorkers()
 {
 	using namespace std::chrono_literals;
@@ -124,9 +142,21 @@ void DrawerThreads::WorkerMain(DrawerThread *thread)
 		start_lock.unlock();
 
 		// Do the work:
-		for (auto& command : list->commands)
+		if (r_debug_draw)
 		{
-			command->Execute(thread);
+			for (auto& command : list->commands)
+			{
+				thread->debug_draw_pos++;
+				if (thread->debug_draw_pos < debug_draw_end)
+					command->Execute(thread);
+			}
+		}
+		else
+		{
+			for (auto& command : list->commands)
+			{
+				command->Execute(thread);
+			}
 		}
 
 		// Notify main thread that we finished:
diff --git a/src/swrenderer/drawers/r_thread.h b/src/swrenderer/drawers/r_thread.h
index 53c9bea44..fe6b9a931 100644
--- a/src/swrenderer/drawers/r_thread.h
+++ b/src/swrenderer/drawers/r_thread.h
@@ -52,6 +52,8 @@ public:
 
 	std::shared_ptr<PolyTriangleThreadData> poly;
 
+	size_t debug_draw_pos = 0;
+
 	// Checks if a line is rendered by this thread
 	bool line_skipped_by_thread(int line)
 	{
@@ -109,6 +111,8 @@ public:
 
 	// Waits for all commands to finish executing
 	static void WaitForWorkers();
+
+	static void ResetDebugDrawPos();
 	
 private:
 	DrawerThreads();
@@ -132,6 +136,8 @@ private:
 	std::condition_variable end_condition;
 	size_t tasks_left = 0;
 
+	size_t debug_draw_end = 0;
+
 	DrawerThread single_core_thread;
 	
 	friend class DrawerCommandQueue;
diff --git a/src/swrenderer/scene/r_scene.cpp b/src/swrenderer/scene/r_scene.cpp
index 8022afa1e..b229367ee 100644
--- a/src/swrenderer/scene/r_scene.cpp
+++ b/src/swrenderer/scene/r_scene.cpp
@@ -65,6 +65,7 @@ void PeekThreadedErrorPane();
 
 EXTERN_CVAR(Bool, r_shadercolormaps)
 EXTERN_CVAR(Int, r_clearbuffer)
+EXTERN_CVAR(Int, r_debug_draw)
 
 CVAR(Bool, r_scene_multithreaded, false, 0);
 CVAR(Bool, r_models, false, 0);
@@ -101,7 +102,7 @@ namespace swrenderer
 		if (r_models)
 			PolyTriangleDrawer::ClearBuffers(viewport->RenderTarget);
 
-		if (r_clearbuffer != 0)
+		if (r_clearbuffer != 0 || r_debug_draw != 0)
 		{
 			if (!viewport->RenderTarget->IsBgra())
 			{
@@ -115,6 +116,7 @@ namespace swrenderer
 				for (int i = 0; i < size; i++)
 					dest[i] = bgracolor;
 			}
+			DrawerThreads::ResetDebugDrawPos();
 		}
 
 		RenderActorView(player->mo);