From be4b0cb67b5bf2328bbdd4d353c6e3164f1f339a Mon Sep 17 00:00:00 2001
From: Magnus Norddahl <dpjudas@users.noreply.github.com>
Date: Mon, 12 May 2025 14:26:24 +0200
Subject: [PATCH] Stop memory allocations by keeping the RectPacker around

---
 .../rendering/hwrenderer/data/hw_rectpacker.cpp | 17 +++++++++++++++++
 .../rendering/hwrenderer/data/hw_rectpacker.h   |  2 ++
 src/common/rendering/vulkan/vk_lightmapper.cpp  |  7 +++++--
 src/common/rendering/vulkan/vk_lightmapper.h    |  2 ++
 4 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/src/common/rendering/hwrenderer/data/hw_rectpacker.cpp b/src/common/rendering/hwrenderer/data/hw_rectpacker.cpp
index ae7c1d003..757f270d9 100644
--- a/src/common/rendering/hwrenderer/data/hw_rectpacker.cpp
+++ b/src/common/rendering/hwrenderer/data/hw_rectpacker.cpp
@@ -16,6 +16,23 @@ RectPacker::RectPacker(int width, int height, int padding) : PageWidth(width), P
 {
 }
 
+void RectPacker::Clear()
+{
+	Pages.clear();
+	ItemFreeList.resize(Items.size());
+	size_t i = Items.size();
+	for (auto& item : Items)
+	{
+		item->Shelf = nullptr;
+		item->PrevItem = nullptr;
+		item->NextItem = nullptr;
+		item->IsAvailable = false;
+		item->PrevAvailable = nullptr;
+		item->NextAvailable = nullptr;
+		ItemFreeList[--i] = item.get();
+	}
+}
+
 RectPackerItem* RectPacker::Alloc(int width, int height)
 {
 	width += Padding * 2;
diff --git a/src/common/rendering/hwrenderer/data/hw_rectpacker.h b/src/common/rendering/hwrenderer/data/hw_rectpacker.h
index d8819108e..433bca9e2 100644
--- a/src/common/rendering/hwrenderer/data/hw_rectpacker.h
+++ b/src/common/rendering/hwrenderer/data/hw_rectpacker.h
@@ -56,6 +56,8 @@ class RectPacker
 public:
 	RectPacker(int width, int height, int padding);
 
+	void Clear();
+
 	RectPackerItem* Alloc(int width, int height);
 	void Free(RectPackerItem* item);
 
diff --git a/src/common/rendering/vulkan/vk_lightmapper.cpp b/src/common/rendering/vulkan/vk_lightmapper.cpp
index e32709d2d..1029ac139 100644
--- a/src/common/rendering/vulkan/vk_lightmapper.cpp
+++ b/src/common/rendering/vulkan/vk_lightmapper.cpp
@@ -133,7 +133,10 @@ void VkLightmapper::SelectTiles(const TArray<LightmapTile*>& tiles)
 	selectedTiles.Clear();
 
 	// We use a 3 texel spacing between rectangles so that the blur pass will not pick up anything from a neighbour tile.
-	RectPacker packer(bakeImageSize, bakeImageSize, 3);
+	if (!packer)
+		packer = std::make_unique<RectPacker>(bakeImageSize, bakeImageSize, 3);
+	else
+		packer->Clear();
 
 	for (int i = 0, count = tiles.Size(); i < count; i++)
 	{
@@ -143,7 +146,7 @@ void VkLightmapper::SelectTiles(const TArray<LightmapTile*>& tiles)
 			continue;
 
 		// Only grab surfaces until our bake texture is full
-		auto result = packer.Alloc(tile->AtlasLocation.Width, tile->AtlasLocation.Height);
+		auto result = packer->Alloc(tile->AtlasLocation.Width, tile->AtlasLocation.Height);
 		if (result->PageIndex == 0)
 		{
 			SelectedTile selected;
diff --git a/src/common/rendering/vulkan/vk_lightmapper.h b/src/common/rendering/vulkan/vk_lightmapper.h
index 80ea7f1ab..7b79aa0a3 100644
--- a/src/common/rendering/vulkan/vk_lightmapper.h
+++ b/src/common/rendering/vulkan/vk_lightmapper.h
@@ -6,6 +6,7 @@
 class VulkanRenderDevice;
 class FString;
 class ShaderIncludeResult;
+class RectPacker;
 
 struct Uniforms
 {
@@ -232,4 +233,5 @@ private:
 
 	LightmapBakeImage bakeImage;
 	static const int bakeImageSize = 2048;
+	std::unique_ptr<RectPacker> packer;
 };