From c915f1bcd46144578fad464e52b5a6013dc98de8 Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Fri, 17 Mar 2023 02:05:42 +0000
Subject: Fix texture packer return value so positions match inputs

---
 assetFactory/texturePacker.cpp | 15 +++++++++------
 assetFactory/texturePacker.h   |  5 +++--
 test/test-assetFactory.cpp     |  5 +++--
 3 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/assetFactory/texturePacker.cpp b/assetFactory/texturePacker.cpp
index 31c9a0e..68a6010 100644
--- a/assetFactory/texturePacker.cpp
+++ b/assetFactory/texturePacker.cpp
@@ -1,14 +1,16 @@
 #include "texturePacker.h"
+#include "collections.hpp"
 #include <algorithm>
 #include <cstdio>
 #include <numeric>
 #include <ostream>
 #include <set>
 
-TexturePacker::TexturePacker(std::vector<Image> in) : inputImages {std::move(in)}
+TexturePacker::TexturePacker(std::span<const Image> in) :
+	inputImages {std::move(in)}, sortedIndexes {vectorOfN(inputImages.size(), size_t {})}
 {
-	std::sort(inputImages.rbegin(), inputImages.rend(), [](const auto & a, const auto & b) {
-		return area(a) < area(b);
+	std::sort(sortedIndexes.rbegin(), sortedIndexes.rend(), [this](const auto a, const auto b) {
+		return area(inputImages[a]) < area(inputImages[b]);
 	});
 }
 
@@ -24,15 +26,16 @@ TexturePacker::pack(Size size) const
 	using Spaces = std::set<Space>;
 	Spaces spaces {{{}, size}};
 
-	Positions result;
-	for (const auto & image : inputImages) {
+	Positions result(inputImages.size());
+	for (const auto & idx : sortedIndexes) {
+		const auto & image = inputImages[idx];
 		if (const auto spaceItr = std::find_if(spaces.begin(), spaces.end(),
 					[image](const Space & s) {
 						return image.x <= s.size.x && image.y <= s.size.y;
 					});
 				spaceItr != spaces.end()) {
 			auto space = *spaceItr;
-			result.push_back(space.position);
+			result[idx] = space.position;
 			spaces.erase(spaceItr);
 			if (space.size.x > image.x) {
 				spaces.emplace(Position {space.position.x + image.x, space.position.y},
diff --git a/assetFactory/texturePacker.h b/assetFactory/texturePacker.h
index 8e2061b..7e00f1a 100644
--- a/assetFactory/texturePacker.h
+++ b/assetFactory/texturePacker.h
@@ -23,7 +23,7 @@ public:
 	using Positions = std::vector<Position>;
 	using Result = std::pair<Positions, Size>;
 
-	TexturePacker(std::vector<Image>);
+	TexturePacker(std::span<const Image>);
 
 	Result pack(Size) const;
 	Result pack() const;
@@ -32,5 +32,6 @@ public:
 	static decltype(Size::x) area(const Size & size);
 
 private:
-	std::vector<Image> inputImages;
+	std::span<const Image> inputImages;
+	std::vector<size_t> sortedIndexes;
 };
diff --git a/test/test-assetFactory.cpp b/test/test-assetFactory.cpp
index ad62a93..d71fa9b 100644
--- a/test/test-assetFactory.cpp
+++ b/test/test-assetFactory.cpp
@@ -129,14 +129,15 @@ BOOST_AUTO_TEST_CASE(parseX11RGB)
 
 BOOST_AUTO_TEST_CASE(texturePacker)
 {
-	TexturePacker tp {{
+	std::vector<TexturePacker::Image> input {
 			{10, 10},
 			{10, 10},
 			{10, 10},
 			{100, 10},
 			{10, 200},
 			{5, 5},
-	}};
+	};
+	TexturePacker tp {input};
 	BOOST_CHECK_EQUAL(TexturePacker::Size(128, 256), tp.minSize());
 	const auto result = tp.pack();
 }
-- 
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