diff --git a/src/common/RasterGeometry.h b/src/common/RasterGeometry.h
index b2cee21d1..1916ee75f 100644
--- a/src/common/RasterGeometry.h
+++ b/src/common/RasterGeometry.h
@@ -121,44 +121,44 @@ void RasterizeEllipseRows(Vec2<float> radiusSquared, F f)
 }
 
 // Call f for every point on the boundary of the indicated rectangle (so that
-// TopLeft and BottomRight are both corners).
+// pos and BottomRight are both corners).
 template<typename F>
 void RasterizeRect(Rect<int> rect, F f)
 {
-	for (int x = rect.TopLeft.X; x <= rect.BottomRight.X; x++)
-		f(Vec2(x, rect.TopLeft.Y));
+	for (int x = rect.pos.X; x < rect.pos.X + rect.size.X; x++)
+		f(Vec2(x, rect.pos.Y));
 
-	if (rect.TopLeft.Y != rect.BottomRight.Y)
-		for (int x = rect.TopLeft.X; x <= rect.BottomRight.X; x++)
-			f(Vec2(x, rect.BottomRight.Y));
+	if (rect.pos.Y != rect.pos.Y + rect.size.Y - 1)
+		for (int x = rect.pos.X; x < rect.pos.X + rect.size.X; x++)
+			f(Vec2(x, rect.pos.Y + rect.size.Y - 1));
 
 	// corners already drawn
-	for (int y = rect.TopLeft.Y + 1; y <= rect.BottomRight.Y - 1; y++)
-		f(Vec2(rect.TopLeft.X, y));
+	for (int y = rect.pos.Y + 1; y < rect.pos.Y + rect.size.Y - 1; y++)
+		f(Vec2(rect.pos.X, y));
 
-	if (rect.TopLeft.X != rect.BottomRight.X)
-		for (int y = rect.TopLeft.Y + 1; y <= rect.BottomRight.Y - 1; y++)
-			f(Vec2(rect.BottomRight.X, y));
+	if (rect.pos.X != rect.pos.X + rect.size.X - 1)
+		for (int y = rect.pos.Y + 1; y < rect.pos.Y + rect.size.Y - 1; y++)
+			f(Vec2(rect.pos.X + rect.size.X - 1, y));
 }
 
 // Call f for every point on the dotted boundary of the indicated rectangle.
 template<typename F>
 void RasterizeDottedRect(Rect<int> rect, F f)
 {
-	for (int x = rect.TopLeft.X; x <= rect.BottomRight.X; x += 2)
-		f(Vec2(x, rect.TopLeft.Y));
+	for (int x = rect.pos.X; x < rect.pos.X + rect.size.X; x += 2)
+		f(Vec2(x, rect.pos.Y));
 
-	int bottomOff = (rect.BottomRight.Y - rect.TopLeft.Y) % 2;
-	if (rect.TopLeft.Y != rect.BottomRight.Y)
-		for (int x = rect.TopLeft.X + bottomOff; x <= rect.BottomRight.X; x += 2)
-			f(Vec2(x, rect.BottomRight.Y));
+	int bottomOff = (rect.pos.Y + rect.size.Y - 1 - rect.pos.Y) % 2;
+	if (rect.pos.Y != rect.pos.Y + rect.size.Y - 1)
+		for (int x = rect.pos.X + bottomOff; x < rect.pos.X + rect.size.X; x += 2)
+			f(Vec2(x, rect.pos.Y + rect.size.Y - 1));
 
 	// corners already drawn
-	for (int y = rect.TopLeft.Y + 1 + 1; y <= rect.BottomRight.Y - 1; y += 2)
-		f(Vec2(rect.TopLeft.X, y));
+	for (int y = rect.pos.Y + 1 + 1; y < rect.pos.Y + rect.size.Y - 1; y += 2)
+		f(Vec2(rect.pos.X, y));
 
-	int leftOff = (rect.BottomRight.X - rect.TopLeft.X + 1) % 2;
-	if (rect.TopLeft.X != rect.BottomRight.X)
-		for (int y = rect.TopLeft.Y + 1 + leftOff; y <= rect.BottomRight.Y - 1; y += 2)
-			f(Vec2(rect.BottomRight.X, y));
+	int leftOff = (rect.pos.X + rect.size.X - 1 - rect.pos.X + 1) % 2;
+	if (rect.pos.X != rect.pos.X + rect.size.X - 1)
+		for (int y = rect.pos.Y + 1 + leftOff; y < rect.pos.Y + rect.size.Y - 1; y += 2)
+			f(Vec2(rect.pos.X + rect.size.X - 1, y));
 }
diff --git a/src/common/Vec2.h b/src/common/Vec2.h
index aee87b7c6..34133f785 100644
--- a/src/common/Vec2.h
+++ b/src/common/Vec2.h
@@ -107,8 +107,8 @@ struct Vec2
 	Vec2<T> Clamp(Rect<T> rect) const
 	{
 		return Vec2<T>(
-			std::clamp(X, rect.TopLeft.X, rect.BottomRight.X),
-			std::clamp(Y, rect.TopLeft.Y, rect.BottomRight.Y)
+			std::clamp(X, rect.pos.X, rect.pos.X + rect.size.X - T(1)),
+			std::clamp(Y, rect.pos.Y, rect.pos.Y + rect.size.Y - T(1))
 		);
 	}
 
@@ -185,8 +185,8 @@ Mat2<T> const Mat2<T, V>::MirrorY = Mat2<T>(1, 0, 0, -1);
 template<typename T, typename V>
 Mat2<T> const Mat2<T, V>::CCW = Mat2<T>(0, 1, -1, 0); // reminder: the Y axis points down
 
-template<typename T, typename = std::enable_if_t<std::is_arithmetic_v<T>>>
-constexpr static inline Rect<T> RectBetween(Vec2<T>, Vec2<T>);
+template<typename T, typename = std::enable_if_t<std::is_integral_v<T>>>
+constexpr static inline Rect<T> RectSized(Vec2<T>, Vec2<T>);
 
 enum IterationDirection
 {
@@ -200,16 +200,15 @@ template<typename T, typename>
 struct Rect
 {
 	// Inclusive
-	Vec2<T> TopLeft, BottomRight;
+	Vec2<T> pos, size;
 
-private:
-	constexpr Rect(Vec2<T> topLeft, Vec2<T> bottomRight):
-		TopLeft(topLeft),
-		BottomRight(bottomRight)
+	constexpr Rect(Vec2<T> newPos, Vec2<T> newSize):
+		pos(newPos),
+		size(newSize)
 	{
 	}
-	friend constexpr Rect<T> RectBetween<T>(Vec2<T>, Vec2<T>);
 
+private:
 	struct end_sentinel
 	{};
 
@@ -350,48 +349,25 @@ private:
 public:
 	constexpr bool operator==(Rect other) const
 	{
-		return TopLeft == other.TopLeft && BottomRight == other.BottomRight;
+		return pos == other.pos && size == other.size;
 	}
 
 	constexpr bool operator!=(Rect other) const
 	{
-		return TopLeft != other.TopLeft || BottomRight != other.BottomRight;
+		return pos != other.pos || size != other.size;
 	}
 
 	constexpr explicit operator bool() const
 	{
-		return BottomRight.X >= TopLeft.X && BottomRight.Y >= TopLeft.Y;
-	}
-
-	// Return the smallest rectangle that contains both input rectangles,
-	// **assuming neither are empty**
-	Rect<T> operator|(Rect<T> other) const
-	{
-		return Rect<T>(
-			Vec2<T>(std::min(TopLeft.X, other.TopLeft.X), std::min(TopLeft.Y, other.TopLeft.Y)),
-			Vec2<T>(std::max(BottomRight.X, other.BottomRight.X), std::max(BottomRight.Y, other.BottomRight.Y))
-		);
+		return size.X > 0 && size.Y > 0;
 	}
 
 	// Return the intersection of two rectangles (possibly empty)
 	Rect<T> operator&(Rect<T> other) const
 	{
-		auto rect = Rect<T>(
-			Vec2<T>(std::max(TopLeft.X, other.TopLeft.X), std::max(TopLeft.Y, other.TopLeft.Y)),
-			Vec2<T>(std::min(BottomRight.X, other.BottomRight.X), std::min(BottomRight.Y, other.BottomRight.Y))
-		);
-		return Rect<T>(
-			rect.TopLeft,
-			Vec2<T>(
-				std::max(rect.TopLeft.X - 1, rect.BottomRight.X),
-				std::max(rect.TopLeft.Y - 1, rect.BottomRight.Y)
-			)
-		);
-	}
-
-	inline Rect<T> &operator|=(Rect<T> other)
-	{
-		return *this = *this | other;
+		auto tl  = Vec2<T>(std::max(pos.X         , other.pos.X               ), std::max(pos.Y         , other.pos.Y               ));
+		auto br1 = Vec2<T>(std::min(pos.X + size.X, other.pos.X + other.size.X), std::min(pos.Y + size.Y, other.pos.Y + other.size.Y));
+		return Rect<T>(tl, br1 - tl);
 	}
 
 	inline Rect<T> &operator&=(Rect<T> other)
@@ -401,19 +377,13 @@ public:
 
 	constexpr bool Contains(Vec2<T> point) const
 	{
-		return point.X >= TopLeft.X && point.X <= BottomRight.X && point.Y >= TopLeft.Y && point.Y <= BottomRight.Y;
-	}
-
-	template<typename S = T, typename = std::enable_if_t<std::is_integral_v<S>>>
-	inline Vec2<T> Size() const
-	{
-		return BottomRight - TopLeft + Vec2<T>(1, 1);
+		return point.X >= pos.X && point.X < pos.X + size.X && point.Y >= pos.Y && point.Y < pos.Y + size.Y;
 	}
 
 	template<typename S>
 	Rect<decltype(std::declval<T>() + std::declval<S>())> Inset(S delta) const
 	{
-		return Rect<decltype(std::declval<T>() + std::declval<S>())>(TopLeft + Vec2(delta, delta), BottomRight - Vec2(delta, delta));
+		return Rect<decltype(std::declval<T>() + std::declval<S>())>(pos + Vec2(delta, delta), size - Vec2(delta, delta) * S(2));
 	}
 
 	template<IterationDirection D1, IterationDirection D2, typename S = T, typename = std::enable_if_t<std::is_integral_v<T>>>
@@ -426,10 +396,10 @@ public:
 		);
 		if constexpr (D1 == TOP_TO_BOTTOM || D1 == BOTTOM_TO_TOP)
 		{
-			return range_row_major<D1, D2>{TopLeft.X, TopLeft.Y, BottomRight.X, BottomRight.Y};
+			return range_row_major<D1, D2>{pos.X, pos.Y, pos.X + size.X - T(1), pos.Y + size.Y - T(1)};
 		}
 		else
-			return range_column_major<D1, D2>{TopLeft.X, TopLeft.Y, BottomRight.X, BottomRight.Y};
+			return range_column_major<D1, D2>{pos.X, pos.Y, pos.X + size.X - T(1), pos.Y + size.Y - T(1)};
 	}
 
 	// Use when the order isn't important
@@ -445,19 +415,19 @@ public:
 };
 
 template<typename T, typename>
+constexpr inline Rect<T> RectSized(Vec2<T> pos, Vec2<T> size)
+{
+	return Rect<T>(pos, size);
+}
+
+template<typename T, typename = std::enable_if_t<std::is_arithmetic_v<T>>>
 constexpr inline Rect<T> RectBetween(Vec2<T> topLeft, Vec2<T> bottomRight)
 {
-	return Rect<T>(topLeft, bottomRight);
+	return RectSized(topLeft, bottomRight - topLeft + Vec2<T>(1, 1));
 }
 
 template<typename T, typename = std::enable_if_t<std::is_arithmetic_v<T>>>
 constexpr inline Rect<T> RectAt(Vec2<T> pos)
 {
-	return RectBetween<T>(pos, pos);
-}
-
-template<typename T, typename = std::enable_if_t<std::is_integral_v<T>>>
-constexpr inline Rect<T> RectSized(Vec2<T> topLeft, Vec2<T> dimen)
-{
-	return RectBetween<T>(topLeft, topLeft + dimen - Vec2<T>(1, 1));
+	return RectSized(pos, Vec2<T>(1, 1));
 }
diff --git a/src/graphics/Graphics.cpp b/src/graphics/Graphics.cpp
index 8e3036508..aa8ff287f 100644
--- a/src/graphics/Graphics.cpp
+++ b/src/graphics/Graphics.cpp
@@ -36,10 +36,10 @@ void VideoBuffer::Crop(Rect<int> rect)
 	if (rect == Size().OriginRect())
 		return;
 
-	PlaneAdapter<std::vector<pixel> &> newVideo(rect.Size(), std::in_place, video.Base);
+	PlaneAdapter<std::vector<pixel> &> newVideo(rect.size, std::in_place, video.Base);
 	for (auto y = 0; y < newVideo.Size().Y; y++)
 		std::copy_n(
-			video.RowIterator(rect.TopLeft + Vec2(0, y)),
+			video.RowIterator(rect.pos + Vec2(0, y)),
 			newVideo.Size().X,
 			newVideo.RowIterator(Vec2(0, y))
 		);
diff --git a/src/graphics/RasterDrawMethodsImpl.h b/src/graphics/RasterDrawMethodsImpl.h
index 5fe5b5492..509f9d596 100644
--- a/src/graphics/RasterDrawMethodsImpl.h
+++ b/src/graphics/RasterDrawMethodsImpl.h
@@ -135,8 +135,8 @@ void RasterDrawMethods<Derived>::DrawFilledRect(Rect<int> rect, RGB<uint8_t> col
 	pixel packed = colour.Pack();
 	auto &video = static_cast<Derived &>(*this).video;
 	if (rect)
-		for (int y = rect.TopLeft.Y; y <= rect.BottomRight.Y; y++)
-			std::fill_n(video.RowIterator(Vec2(rect.TopLeft.X, y)), rect.Size().X, packed);
+		for (int y = rect.pos.Y; y < rect.pos.Y + rect.size.Y; y++)
+			std::fill_n(video.RowIterator(Vec2(rect.pos.X, y)), rect.size.X, packed);
 }
 
 template<typename Derived>
@@ -166,22 +166,22 @@ void RasterDrawMethods<Derived>::BlendFilledEllipse(Vec2<int> center, Vec2<int>
 template<typename Derived>
 void RasterDrawMethods<Derived>::BlendImage(pixel const *data, uint8_t alpha, Rect<int> rect)
 {
-	BlendImage(data, alpha, rect, rect.Size().X);
+	BlendImage(data, alpha, rect, rect.size.X);
 }
 
 template<typename Derived>
 void RasterDrawMethods<Derived>::BlendImage(pixel const *data, uint8_t alpha, Rect<int> rect, size_t rowStride)
 {
-	auto origin = rect.TopLeft;
+	auto origin = rect.pos;
 	rect &= clipRect();
 	if (alpha == 0xFF)
 	{
 		auto &video = static_cast<Derived &>(*this).video;
-		for (int y = rect.TopLeft.Y; y <= rect.BottomRight.Y; y++)
+		for (int y = rect.pos.Y; y < rect.pos.Y + rect.size.Y; y++)
 			std::copy_n(
-				data + (rect.TopLeft.X - origin.X) + (y - origin.Y) * rowStride,
-				rect.Size().X,
-				video.RowIterator(Vec2(rect.TopLeft.X, y))
+				data + (rect.pos.X - origin.X) + (y - origin.Y) * rowStride,
+				rect.size.X,
+				video.RowIterator(Vec2(rect.pos.X, y))
 			);
 	}
 	else
@@ -197,13 +197,13 @@ void RasterDrawMethods<Derived>::BlendImage(pixel const *data, uint8_t alpha, Re
 template<typename Derived>
 void RasterDrawMethods<Derived>::XorImage(unsigned char const *data, Rect<int> rect)
 {
-	XorImage(data, rect, rect.Size().X);
+	XorImage(data, rect, rect.size.X);
 }
 
 template<typename Derived>
 void RasterDrawMethods<Derived>::XorImage(unsigned char const *data, Rect<int> rect, size_t rowStride)
 {
-	auto origin = rect.TopLeft;
+	auto origin = rect.pos;
 	rect &= clipRect();
 	for (auto pos : rect)
 		if (data[(pos.X - origin.X) + (pos.Y - origin.Y) * rowStride])
@@ -213,13 +213,13 @@ void RasterDrawMethods<Derived>::XorImage(unsigned char const *data, Rect<int> r
 template<typename Derived>
 void RasterDrawMethods<Derived>::BlendRGBAImage(pixel_rgba const *data, Rect<int> rect)
 {
-	BlendRGBAImage(data, rect, rect.Size().X);
+	BlendRGBAImage(data, rect, rect.size.X);
 }
 
 template<typename Derived>
 void RasterDrawMethods<Derived>::BlendRGBAImage(pixel_rgba const *data, Rect<int> rect, size_t rowStride)
 {
-	auto origin = rect.TopLeft;
+	auto origin = rect.pos;
 	rect &= clipRect();
 	for (auto pos : rect)
 	{
diff --git a/src/gui/game/ToolButton.cpp b/src/gui/game/ToolButton.cpp
index 1e703f231..0b24349d9 100644
--- a/src/gui/game/ToolButton.cpp
+++ b/src/gui/game/ToolButton.cpp
@@ -50,7 +50,7 @@ void ToolButton::Draw(const ui::Point& screenPos)
 {
 	Graphics * g = GetGraphics();
 	auto rect = ClipRect;
-	if (ClipRect.Size().X && ClipRect.Size().Y)
+	if (ClipRect.size.X && ClipRect.size.Y)
 		g->SwapClipRect(rect); // old cliprect is now in rect
 
 	int totalColour = Appearance.BackgroundInactive.Blue + (3*Appearance.BackgroundInactive.Green) + (2*Appearance.BackgroundInactive.Red);
@@ -87,7 +87,7 @@ void ToolButton::Draw(const ui::Point& screenPos)
 		g->BlendText(screenPos + textPosition, buttonDisplayText, 0x000000_rgb .WithAlpha(255));
 	}
 
-	if (ClipRect.Size().X && ClipRect.Size().Y)
+	if (ClipRect.size.X && ClipRect.size.Y)
 		g->SwapClipRect(rect); // apply old clip rect
 }
 
diff --git a/src/gui/interface/Panel.cpp b/src/gui/interface/Panel.cpp
index 36e26f342..f49e29a30 100644
--- a/src/gui/interface/Panel.cpp
+++ b/src/gui/interface/Panel.cpp
@@ -80,7 +80,7 @@ void Panel::Draw(const Point& screenPos)
 			//check if the component is in the screen, draw if it is
 			if (rect & Size.OriginRect())
 			{
-				child->Draw(screenPos + rect.TopLeft);
+				child->Draw(screenPos + rect.pos);
 			}
 		}
 
diff --git a/src/gui/interface/ProgressBar.cpp b/src/gui/interface/ProgressBar.cpp
index e9c1b1052..c29c30cd6 100644
--- a/src/gui/interface/ProgressBar.cpp
+++ b/src/gui/interface/ProgressBar.cpp
@@ -46,7 +46,7 @@ void ProgressBar::Draw(const Point &screenPos)
 	g->DrawRect(RectSized(screenPos, Size), 0xFFFFFF_rgb);
 	auto inner = RectSized(screenPos + Vec2{ 2, 2 }, Size - Vec2{ 4, 4 });
 	auto drawContent = [this, screenPos, g, inner](int beginX, int endX, ui::Colour bgColour, ui::Colour textColour) {
-		auto clip = RectSized(inner.TopLeft + Vec2{ beginX, 0 }, Vec2{ endX - beginX, inner.Size().Y }) & g->GetClipRect();
+		auto clip = RectSized(inner.pos + Vec2{ beginX, 0 }, Vec2{ endX - beginX, inner.size.Y }) & g->GetClipRect();
 		g->SwapClipRect(clip);
 		if (bgColour.Alpha)
 		{
@@ -58,18 +58,18 @@ void ProgressBar::Draw(const Point &screenPos)
 		}, progressStatus, textColour);
 		g->SwapClipRect(clip);
 	};
-	drawContent(0, inner.Size().X, 0x000000_rgb .WithAlpha(0), 0xFFFFFF_rgb .WithAlpha(255));
+	drawContent(0, inner.size.X, 0x000000_rgb .WithAlpha(0), 0xFFFFFF_rgb .WithAlpha(255));
 	if (progress == -1)
 	{
 		constexpr auto size = 40;
-		auto pos = int(inner.Size().X * intermediatePos / 100);
+		auto pos = int(inner.size.X * intermediatePos / 100);
 		drawContent(pos, pos + size, style::Colour::WarningTitle, 0x000000_rgb .WithAlpha(255));
-		pos -= inner.Size().X;
+		pos -= inner.size.X;
 		drawContent(pos, pos + size, style::Colour::WarningTitle, 0x000000_rgb .WithAlpha(255));
 	}
 	else
 	{
-		drawContent(0, inner.Size().X * progress / 100, style::Colour::WarningTitle, 0x000000_rgb .WithAlpha(255));
+		drawContent(0, inner.size.X * progress / 100, style::Colour::WarningTitle, 0x000000_rgb .WithAlpha(255));
 	}
 }
 
diff --git a/src/gui/interface/Window.cpp b/src/gui/interface/Window.cpp
index cb8534986..8de1a0e24 100644
--- a/src/gui/interface/Window.cpp
+++ b/src/gui/interface/Window.cpp
@@ -189,7 +189,7 @@ void Window::DoDraw()
 		{
 			auto rect = RectSized(Position + child->Position, child->Size);
 			if (AllowExclusiveDrawing || bool(rect & GetGraphics()->Size().OriginRect()))
-				child->Draw(rect.TopLeft);
+				child->Draw(rect.pos);
 		}
 	};
 	for (auto child : Components)
diff --git a/src/lua/LuaGraphics.cpp b/src/lua/LuaGraphics.cpp
index f6c746824..aaf2f0a21 100644
--- a/src/lua/LuaGraphics.cpp
+++ b/src/lua/LuaGraphics.cpp
@@ -261,10 +261,10 @@ static int setClipRect(lua_State *L)
 	int h = luaL_optinteger(L, 4, WINDOWH);
 	auto rect = RectSized(Vec2(x, y), Vec2(w, h));
 	lsi->g->SwapClipRect(rect);
-	lua_pushinteger(L, rect.TopLeft.X);
-	lua_pushinteger(L, rect.TopLeft.Y);
-	lua_pushinteger(L, rect.Size().X);
-	lua_pushinteger(L, rect.Size().Y);
+	lua_pushinteger(L, rect.pos.X);
+	lua_pushinteger(L, rect.pos.Y);
+	lua_pushinteger(L, rect.size.X);
+	lua_pushinteger(L, rect.size.Y);
 	return 4;
 }
 
diff --git a/src/simulation/Editing.cpp b/src/simulation/Editing.cpp
index 1bd8d4ccd..e2ea0ceda 100644
--- a/src/simulation/Editing.cpp
+++ b/src/simulation/Editing.cpp
@@ -85,10 +85,10 @@ void Simulation::Restore(const Snapshot &snap)
 void Simulation::clear_area(int area_x, int area_y, int area_w, int area_h)
 {
 	auto intersection = RES.OriginRect() & RectSized(Vec2{ area_x, area_y }, Vec2{ area_w, area_h });
-	area_x = intersection.TopLeft.X;
-	area_y = intersection.TopLeft.Y;
-	area_w = intersection.Size().X;
-	area_h = intersection.Size().Y;
+	area_x = intersection.pos.X;
+	area_y = intersection.pos.Y;
+	area_w = intersection.size.X;
+	area_h = intersection.size.Y;
 	float fx = area_x-.5f, fy = area_y-.5f;
 	for (int i = 0; i <= parts_lastActiveIndex; i++)
 	{
diff --git a/src/simulation/Simulation.cpp b/src/simulation/Simulation.cpp
index c3507daaa..2b9b43444 100644
--- a/src/simulation/Simulation.cpp
+++ b/src/simulation/Simulation.cpp
@@ -53,20 +53,20 @@ void Simulation::Load(const GameSave *save, bool includePressure, Vec2<int> bloc
 	std::sort(existingParticles.begin(), existingParticles.end(), [](const auto &lhs, const auto &rhs) {
 		return std::tie(lhs.pos.Y, lhs.pos.X) < std::tie(rhs.pos.Y, rhs.pos.X);
 	});
-	PlaneAdapter<std::vector<size_t>> existingParticleIndices(pasteArea.Size(), existingParticles.size());
+	PlaneAdapter<std::vector<size_t>> existingParticleIndices(pasteArea.size, existingParticles.size());
 	{
 		auto lastPos = Vec2<int>{ -1, -1 }; // not a valid pos in existingParticles
 		for (auto it = existingParticles.begin(); it != existingParticles.end(); ++it)
 		{
 			if (lastPos != it->pos)
 			{
-				existingParticleIndices[it->pos - pasteArea.TopLeft] = it - existingParticles.begin();
+				existingParticleIndices[it->pos - pasteArea.pos] = it - existingParticles.begin();
 				lastPos = it->pos;
 			}
 		}
 	}
 	auto removeExistingParticles = [this, pasteArea, &existingParticles, &existingParticleIndices](Vec2<int> p) {
-		auto rp = p - pasteArea.TopLeft;
+		auto rp = p - pasteArea.pos;
 		if (existingParticleIndices.Size().OriginRect().Contains(rp))
 		{
 			auto index = existingParticleIndices[rp];
@@ -312,10 +312,10 @@ void Simulation::Load(const GameSave *save, bool includePressure, Vec2<int> bloc
 
 std::unique_ptr<GameSave> Simulation::Save(bool includePressure, Rect<int> partR) // particle coordinates
 {
-	auto blockR = RectBetween(partR.TopLeft / CELL, partR.BottomRight / CELL);
-	auto blockP = blockR.TopLeft;
+	auto blockR = RectSized(partR.pos / CELL, partR.size / CELL);
+	auto blockP = blockR.pos;
 
-	auto newSave = std::make_unique<GameSave>(blockR.Size());
+	auto newSave = std::make_unique<GameSave>(blockR.size);
 	newSave->frameCount = frameCount;
 	newSave->rngState = rng.state();