diff --git a/CMakeLists.txt b/CMakeLists.txt
index 80a049d..1e43796 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -170,6 +170,8 @@ set(SOURCE_FILES
         SpaceCadetPinball/imstb_textedit.h
         SpaceCadetPinball/imstb_rectpack.h
         SpaceCadetPinball/imstb_truetype.h
+        SpaceCadetPinball/DebugOverlay.cpp
+        SpaceCadetPinball/DebugOverlay.h
         )
 
 # On Windows, include resource file with the icon
diff --git a/SpaceCadetPinball/DebugOverlay.cpp b/SpaceCadetPinball/DebugOverlay.cpp
new file mode 100644
index 0000000..2c1f226
--- /dev/null
+++ b/SpaceCadetPinball/DebugOverlay.cpp
@@ -0,0 +1,255 @@
+#include "pch.h"
+#include "DebugOverlay.h"
+
+#include "maths.h"
+#include "proj.h"
+#include "winmain.h"
+#include "TFlipperEdge.h"
+#include "TFlipper.h"
+#include "pb.h"
+#include "TLine.h"
+#include "TCircle.h"
+#include "TPinballTable.h"
+#include "TEdgeBox.h"
+#include "TTableLayer.h"
+#include "TBall.h"
+#include "render.h"
+#include "options.h"
+
+
+gdrv_bitmap8* DebugOverlay::dbScreen = nullptr;
+
+int SDL_RenderDrawCircle(SDL_Renderer* renderer, int x, int y, int radius)
+{
+	int offsetx, offsety, d;
+	int status;
+
+	offsetx = 0;
+	offsety = radius;
+	d = radius - 1;
+	status = 0;
+
+	while (offsety >= offsetx) {
+		status += SDL_RenderDrawPoint(renderer, x + offsetx, y + offsety);
+		status += SDL_RenderDrawPoint(renderer, x + offsety, y + offsetx);
+		status += SDL_RenderDrawPoint(renderer, x - offsetx, y + offsety);
+		status += SDL_RenderDrawPoint(renderer, x - offsety, y + offsetx);
+		status += SDL_RenderDrawPoint(renderer, x + offsetx, y - offsety);
+		status += SDL_RenderDrawPoint(renderer, x + offsety, y - offsetx);
+		status += SDL_RenderDrawPoint(renderer, x - offsetx, y - offsety);
+		status += SDL_RenderDrawPoint(renderer, x - offsety, y - offsetx);
+
+		if (status < 0) {
+			status = -1;
+			break;
+		}
+
+		if (d >= 2 * offsetx) {
+			d -= 2 * offsetx + 1;
+			offsetx += 1;
+		}
+		else if (d < 2 * (radius - offsety)) {
+			d += 2 * offsety - 1;
+			offsety -= 1;
+		}
+		else {
+			d += 2 * (offsety - offsetx - 1);
+			offsety -= 1;
+			offsetx += 1;
+		}
+	}
+
+	return status;
+}
+
+void DebugOverlay::UnInit()
+{
+	delete dbScreen;
+	dbScreen = nullptr;
+}
+
+void DebugOverlay::DrawOverlay()
+{
+	if (dbScreen == nullptr)
+	{
+		dbScreen = new gdrv_bitmap8(render::vscreen->Width, render::vscreen->Height, false, false);
+		dbScreen->CreateTexture("nearest", SDL_TEXTUREACCESS_TARGET);
+		SDL_SetTextureBlendMode(dbScreen->Texture, SDL_BLENDMODE_BLEND);
+	}
+
+	// Setup overlay rendering
+	Uint8 initialR, initialG, initialB, initialA;
+	auto initialRenderTarget = SDL_GetRenderTarget(winmain::Renderer);
+	SDL_GetRenderDrawColor(winmain::Renderer, &initialR, &initialG, &initialB, &initialA);
+	SDL_SetRenderTarget(winmain::Renderer, dbScreen->Texture);
+	SDL_SetRenderDrawColor(winmain::Renderer, 0, 0, 0, 0);
+	SDL_RenderClear(winmain::Renderer);
+
+	// Draw EdgeManager box grid
+	if (options::Options.DebugOverlayGrid)
+		DrawBoxGrid();
+
+	// Draw all edges registered in TCollisionComponent.EdgeList + flippers
+	if (options::Options.DebugOverlayAllEdges)
+		DrawAllEdges();
+
+	// Draw ball collision
+	if (options::Options.DebugOverlayBallPosition || options::Options.DebugOverlayBallEdges)
+		DrawBallInfo();
+
+	// Restore render target
+	SDL_SetRenderTarget(winmain::Renderer, initialRenderTarget);
+	SDL_SetRenderDrawColor(winmain::Renderer,
+		initialR, initialG, initialB, initialA);
+
+	// Copy overlay with alpha blending
+	SDL_BlendMode blendMode;
+	SDL_GetRenderDrawBlendMode(winmain::Renderer, &blendMode);
+	SDL_SetRenderDrawBlendMode(winmain::Renderer, SDL_BLENDMODE_BLEND);
+	SDL_RenderCopy(winmain::Renderer, dbScreen->Texture, nullptr, &render::DestinationRect);
+	SDL_SetRenderDrawBlendMode(winmain::Renderer, blendMode);
+}
+
+void DebugOverlay::DrawBoxGrid()
+{
+	auto& edgeMan = *TTableLayer::edge_manager;
+
+	SDL_SetRenderDrawColor(winmain::Renderer, 0, 255, 0, 255);
+	for (int x = 0; x <= edgeMan.MaxBoxX; x++)
+	{
+		vector2 boxPt{ x * edgeMan.AdvanceX + edgeMan.X , edgeMan.Y };
+		auto pt1 = proj::xform_to_2d(boxPt);
+		boxPt.Y = edgeMan.MaxBoxY * edgeMan.AdvanceY + edgeMan.Y;
+		auto pt2 = proj::xform_to_2d(boxPt);
+
+		SDL_RenderDrawLine(winmain::Renderer, pt1.X, pt1.Y, pt2.X, pt2.Y);
+	}
+	for (int y = 0; y <= edgeMan.MaxBoxY; y++)
+	{
+		vector2 boxPt{ edgeMan.X, y * edgeMan.AdvanceY + edgeMan.Y };
+		auto pt1 = proj::xform_to_2d(boxPt);
+		boxPt.X = edgeMan.MaxBoxX * edgeMan.AdvanceX + edgeMan.X;
+		auto pt2 = proj::xform_to_2d(boxPt);
+
+		SDL_RenderDrawLine(winmain::Renderer, pt1.X, pt1.Y, pt2.X, pt2.Y);
+	}
+}
+
+void DebugOverlay::DrawAllEdges()
+{
+	SDL_SetRenderDrawColor(winmain::Renderer, 0, 200, 200, 255);
+	for (auto cmp : pb::MainTable->ComponentList)
+	{
+		auto collCmp = dynamic_cast<TCollisionComponent*>(cmp);
+		if (collCmp)
+		{
+			for (auto edge : collCmp->EdgeList)
+			{
+				DrawEdge(edge);
+			}
+		}
+		auto flip = dynamic_cast<TFlipper*>(cmp);
+		if (flip)
+		{
+			DrawEdge(flip->FlipperEdge);
+		}
+	}
+}
+
+void DebugOverlay::DrawBallInfo()
+{
+	auto& edgeMan = *TTableLayer::edge_manager;
+	for (auto ball : pb::MainTable->BallList)
+	{
+		if (ball->ActiveFlag)
+		{
+			vector2 ballPosition = { ball->Position.X, ball->Position.Y };
+
+			if (options::Options.DebugOverlayBallEdges)
+			{
+				SDL_SetRenderDrawColor(winmain::Renderer, 255, 0, 0, 255);
+				auto x = edgeMan.box_x(ballPosition.X), y = edgeMan.box_y(ballPosition.Y);
+				auto& box = edgeMan.BoxArray[x + y * edgeMan.MaxBoxX];
+				for (auto edge : box.EdgeList)
+				{
+					DrawEdge(edge);
+				}
+			}
+
+			if (options::Options.DebugOverlayBallPosition)
+			{
+				SDL_SetRenderDrawColor(winmain::Renderer, 0, 0, 255, 255);
+
+				auto pt1 = proj::xform_to_2d(ballPosition);
+				SDL_RenderDrawCircle(winmain::Renderer, pt1.X, pt1.Y, 10);
+
+				auto nextPos = ballPosition;
+				maths::vector_add(nextPos, maths::vector_mul(ball->Acceleration, ball->Speed / 10.0f));
+				auto pt2 = proj::xform_to_2d(nextPos);
+				SDL_RenderDrawLine(winmain::Renderer, pt1.X, pt1.Y, pt2.X, pt2.Y);
+			}
+		}
+	}
+}
+
+void DebugOverlay::DrawCicleType(circle_type& circle)
+{
+	vector2 linePt{ circle.Center.X + sqrt(circle.RadiusSq), circle.Center.Y };
+	auto pt1 = proj::xform_to_2d(circle.Center);
+	auto pt2 = proj::xform_to_2d(linePt);
+	auto radius = abs(pt2.X - pt1.X);
+
+	SDL_RenderDrawCircle(winmain::Renderer, pt1.X, pt1.Y, radius);
+}
+
+void DebugOverlay::DrawLineType(line_type& line)
+{
+	auto pt1 = proj::xform_to_2d(line.Origin);
+	auto pt2 = proj::xform_to_2d(line.End);
+
+	SDL_RenderDrawLine(winmain::Renderer, pt1.X, pt1.Y, pt2.X, pt2.Y);
+}
+
+void DebugOverlay::DrawEdge(TEdgeSegment* edge)
+{
+	if (options::Options.DebugOverlayCollisionMask)
+	{
+		TBall* refBall = nullptr;
+		for (auto ball : pb::MainTable->BallList)
+		{
+			if (ball->ActiveFlag)
+			{
+				refBall = ball;
+				break;
+			}
+		}
+		if (refBall != nullptr && (refBall->FieldFlag & edge->CollisionGroup) == 0)
+			return;
+	}
+
+	auto line = dynamic_cast<TLine*>(edge);
+	if (line)
+	{
+		DrawLineType(line->Line);
+		return;
+	}
+
+	auto circle = dynamic_cast<TCircle*>(edge);
+	if (circle)
+	{
+		DrawCicleType(circle->Circle);
+		return;
+	}
+
+	auto flip = dynamic_cast<TFlipperEdge*>(edge);
+	if (flip)
+	{
+		flip->set_control_points(pb::time_now);
+		flip->build_edges_in_motion();
+
+		DrawLineType(TFlipperEdge::lineA);
+		DrawLineType(TFlipperEdge::lineB);
+		DrawCicleType(TFlipperEdge::circlebase);
+		DrawCicleType(TFlipperEdge::circleT1);
+	}
+}
diff --git a/SpaceCadetPinball/DebugOverlay.h b/SpaceCadetPinball/DebugOverlay.h
new file mode 100644
index 0000000..136b7ce
--- /dev/null
+++ b/SpaceCadetPinball/DebugOverlay.h
@@ -0,0 +1,22 @@
+#pragma once
+
+struct gdrv_bitmap8;
+struct circle_type;
+struct line_type;
+class TEdgeSegment;
+
+class DebugOverlay
+{
+public:
+	static void UnInit();
+	static void DrawOverlay();
+private:
+	static gdrv_bitmap8* dbScreen;
+
+	static void DrawCicleType(circle_type& circle);
+	static void DrawLineType(line_type& line);
+	static void DrawEdge(TEdgeSegment* edge);
+	static void DrawBoxGrid();
+	static void DrawAllEdges();
+	static void DrawBallInfo();
+};
\ No newline at end of file
diff --git a/SpaceCadetPinball/GroupData.cpp b/SpaceCadetPinball/GroupData.cpp
index dbffde3..eda4d73 100644
--- a/SpaceCadetPinball/GroupData.cpp
+++ b/SpaceCadetPinball/GroupData.cpp
@@ -47,7 +47,7 @@ void GroupData::AddEntry(EntryData* entry)
 			if (srcBmp->BitmapType == BitmapTypes::Spliced)
 			{
 				// Get rid of spliced bitmap early on, to simplify render pipeline
-				auto bmp = new gdrv_bitmap8(srcBmp->Width, srcBmp->Height, srcBmp->Width);
+				auto bmp = new gdrv_bitmap8(srcBmp->Width, srcBmp->Height, true);
 				auto zMap = new zmap_header_type(srcBmp->Width, srcBmp->Height, srcBmp->Width);
 				SplitSplicedBitmap(*srcBmp, *bmp, *zMap);
 
diff --git a/SpaceCadetPinball/TBall.cpp b/SpaceCadetPinball/TBall.cpp
index f19bcad..823df3f 100644
--- a/SpaceCadetPinball/TBall.cpp
+++ b/SpaceCadetPinball/TBall.cpp
@@ -50,7 +50,7 @@ TBall::TBall(TPinballTable* table) : TPinballComponent(table, -1, false)
 		if (ListBitmap)
 			ListBitmap->push_back(visual.Bitmap);
 		auto visVec = reinterpret_cast<vector3*>(loader::query_float_attribute(groupIndex, index, 501));
-		auto zDepth = proj::z_distance(visVec);
+		auto zDepth = proj::z_distance(*visVec);
 		VisualZArray[index] = zDepth;
 	}
 	RenderSprite = render::create_sprite(VisualTypes::Ball, nullptr, nullptr, 0, 0, nullptr);
@@ -60,8 +60,6 @@ TBall::TBall(TPinballTable* table) : TPinballComponent(table, -1, false)
 
 void TBall::Repaint()
 {
-	int pos2D[2];
-
 	if (CollisionFlag)
 	{
 		Position.Z =
@@ -70,8 +68,8 @@ void TBall::Repaint()
 			Offset + CollisionOffset.Z;
 	}
 
-	proj::xform_to_2d(&Position, pos2D);
-	auto zDepth = proj::z_distance(&Position);
+	auto pos2D = proj::xform_to_2d(Position);
+	auto zDepth = proj::z_distance(Position);
 
 	auto zArrPtr = VisualZArray;
 	auto index = 0u;
@@ -85,8 +83,8 @@ void TBall::Repaint()
 		RenderSprite,
 		bmp,
 		zDepth,
-		pos2D[0] - bmp->Width / 2,
-		pos2D[1] - bmp->Height / 2);
+		pos2D.X - bmp->Width / 2,
+		pos2D.Y - bmp->Height / 2);
 }
 
 void TBall::not_again(TEdgeSegment* edge)
diff --git a/SpaceCadetPinball/gdrv.cpp b/SpaceCadetPinball/gdrv.cpp
index fc46860..048bd98 100644
--- a/SpaceCadetPinball/gdrv.cpp
+++ b/SpaceCadetPinball/gdrv.cpp
@@ -9,7 +9,15 @@
 
 ColorRgba gdrv::current_palette[256]{};
 
-gdrv_bitmap8::gdrv_bitmap8(int width, int height, bool indexed)
+gdrv_bitmap8::gdrv_bitmap8(int width, int height) : gdrv_bitmap8(width, height, true, true)
+{
+}
+
+gdrv_bitmap8::gdrv_bitmap8(int width, int height, bool indexed) : gdrv_bitmap8(width, height, indexed, true)
+{
+}
+
+gdrv_bitmap8::gdrv_bitmap8(int width, int height, bool indexed, bool bmpBuff)
 {
 	assertm(width >= 0 && height >= 0, "Negative bitmap8 dimensions");
 
@@ -20,13 +28,15 @@ gdrv_bitmap8::gdrv_bitmap8(int width, int height, bool indexed)
 	BitmapType = BitmapTypes::DibBitmap;
 	Texture = nullptr;
 	IndexedBmpPtr = nullptr;
+	BmpBufPtr1 = nullptr;
 	XPosition = 0;
 	YPosition = 0;
 	Resolution = 0;
 
 	if (indexed)
 		IndexedBmpPtr = new char[Height * IndexedStride];
-	BmpBufPtr1 = new ColorRgba[Height * Stride];
+	if (bmpBuff)
+		BmpBufPtr1 = new ColorRgba[Height * Stride];
 }
 
 gdrv_bitmap8::gdrv_bitmap8(const dat8BitBmpHeader& header)
diff --git a/SpaceCadetPinball/gdrv.h b/SpaceCadetPinball/gdrv.h
index f30fd96..cc27f15 100644
--- a/SpaceCadetPinball/gdrv.h
+++ b/SpaceCadetPinball/gdrv.h
@@ -47,7 +47,9 @@ static_assert(sizeof(ColorRgba) == 4, "Wrong size of RGBA color");
 
 struct gdrv_bitmap8
 {
+	gdrv_bitmap8(int width, int height);
 	gdrv_bitmap8(int width, int height, bool indexed);
+	gdrv_bitmap8(int width, int height, bool indexed, bool bmpBuff);
 	gdrv_bitmap8(const struct dat8BitBmpHeader& header);
 	~gdrv_bitmap8();
 	void ScaleIndexed(float scaleX, float scaleY);
diff --git a/SpaceCadetPinball/maths.cpp b/SpaceCadetPinball/maths.cpp
index 069bec4..0ae2250 100644
--- a/SpaceCadetPinball/maths.cpp
+++ b/SpaceCadetPinball/maths.cpp
@@ -132,6 +132,7 @@ float maths::normalize_2d(vector2& vec)
 void maths::line_init(line_type& line, float x0, float y0, float x1, float y1)
 {
 	line.Origin = { x0, y0 };
+	line.End = { x1, y1 };
 	line.Direction.X = x1 - x0;
 	line.Direction.Y = y1 - y0;
 	normalize_2d(line.Direction);
@@ -219,6 +220,11 @@ vector2 maths::vector_sub(const vector2& vec1, const vector2& vec2)
 	return { vec1.X - vec2.X, vec1.Y - vec2.Y };
 }
 
+vector2 maths::vector_mul(const vector2& vec1, float val)
+{
+	return { vec1.X * val, vec1.Y * val };
+}
+
 float maths::basic_collision(TBall* ball, vector2* nextPosition, vector2* direction, float elasticity, float smoothness,
                              float threshold, float boost)
 {
diff --git a/SpaceCadetPinball/maths.h b/SpaceCadetPinball/maths.h
index ce7a67a..863eccc 100644
--- a/SpaceCadetPinball/maths.h
+++ b/SpaceCadetPinball/maths.h
@@ -19,9 +19,18 @@ struct vector2
 
 struct vector3 :vector2
 {	
+	vector3() = default;
+	vector3(float x, float y) : vector3{ x, y, 0 } {}
+	vector3(float x, float y, float z) : vector2{ x, y }, Z(z) {}
 	float Z;
 };
 
+struct vector2i
+{
+	int X;
+	int Y;
+};
+
 struct rectangle_type
 {
 	int XPosition;
@@ -52,6 +61,7 @@ struct line_type
 	vector2 PerpendicularC;
 	vector2 Direction;
 	vector2 Origin;
+	vector2 End;
 	float MinCoord;
 	float MaxCoord;
 	vector2 RayIntersect;
@@ -98,6 +108,7 @@ public:
 	static float magnitude(const vector3& vec);
 	static void vector_add(vector2& vec1Dst, const vector2& vec2);
 	static vector2 vector_sub(const vector2& vec1, const vector2& vec2);
+	static vector2 vector_mul(const vector2& vec1, float val);
 	static float basic_collision(TBall* ball, vector2* nextPosition, vector2* direction, float elasticity,
 	                             float smoothness,
 	                             float threshold, float boost);
diff --git a/SpaceCadetPinball/options.cpp b/SpaceCadetPinball/options.cpp
index d05074e..f0ebb5c 100644
--- a/SpaceCadetPinball/options.cpp
+++ b/SpaceCadetPinball/options.cpp
@@ -104,6 +104,12 @@ void options::InitPrimary()
 	Options.IntegerScaling = get_int("Integer Scaling", false);
 	Options.SoundVolume = Clamp(get_int("Sound Volume", DefVolume), MinVolume, MaxVolume);
 	Options.MusicVolume = Clamp(get_int("Music Volume", DefVolume), MinVolume, MaxVolume);
+	Options.DebugOverlay = get_int("Debug Overlay", false);
+	Options.DebugOverlayGrid = get_int("Debug Overlay Grid", true);
+	Options.DebugOverlayAllEdges = get_int("Debug Overlay All Edges", true);
+	Options.DebugOverlayBallPosition = get_int("Debug Overlay Ball Position", true);
+	Options.DebugOverlayBallEdges = get_int("Debug Overlay Ball Edges", true);
+	Options.DebugOverlayCollisionMask = get_int("Debug Overlay Collision Mask", true);
 }
 
 void options::InitSecondary()
@@ -143,6 +149,12 @@ void options::uninit()
 	set_int("Integer Scaling", Options.IntegerScaling);
 	set_int("Sound Volume", Options.SoundVolume);
 	set_int("Music Volume", Options.MusicVolume);
+	set_int("Debug Overlay", Options.DebugOverlay);
+	set_int("Debug Overlay Grid", Options.DebugOverlayGrid);
+	set_int("Debug Overlay All Edges", Options.DebugOverlayAllEdges);
+	set_int("Debug Overlay Ball Position", Options.DebugOverlayBallPosition);
+	set_int("Debug Overlay Ball Edges", Options.DebugOverlayBallEdges);
+	set_int("Debug Overlay Collision Mask", Options.DebugOverlayCollisionMask);
 }
 
 
diff --git a/SpaceCadetPinball/options.h b/SpaceCadetPinball/options.h
index 7ba4a20..202871b 100644
--- a/SpaceCadetPinball/options.h
+++ b/SpaceCadetPinball/options.h
@@ -80,6 +80,12 @@ struct optionsStruct
 	bool IntegerScaling;
 	int SoundVolume;
 	int MusicVolume;
+	bool DebugOverlay;
+	bool DebugOverlayGrid;
+	bool DebugOverlayAllEdges;
+	bool DebugOverlayBallPosition;
+	bool DebugOverlayBallEdges;
+	bool DebugOverlayCollisionMask;
 };
 
 struct ControlRef
diff --git a/SpaceCadetPinball/proj.cpp b/SpaceCadetPinball/proj.cpp
index c53ddc7..7491591 100644
--- a/SpaceCadetPinball/proj.cpp
+++ b/SpaceCadetPinball/proj.cpp
@@ -26,33 +26,42 @@ void proj::init(float* mat4x3, float d, float centerX, float centerY)
 	centery = centerY;
 }
 
-void proj::matrix_vector_multiply(mat4_row_major* mat, vector3* vec, vector3* dstVec)
+vector3 proj::matrix_vector_multiply(const mat4_row_major& mat, const vector3& vec)
 {
-	const float x = vec->X, y = vec->Y, z = vec->Z;
-	dstVec->X = z * mat->Row0.Z + y * mat->Row0.Y + x * mat->Row0.X + mat->Row0.W;
-	dstVec->Y = z * mat->Row1.Z + y * mat->Row1.Y + x * mat->Row1.X + mat->Row1.W;
-	dstVec->Z = z * mat->Row2.Z + y * mat->Row2.Y + x * mat->Row2.X + mat->Row2.W;
+	vector3 dstVec;
+	const float x = vec.X, y = vec.Y, z = vec.Z;
+	dstVec.X = z * mat.Row0.Z + y * mat.Row0.Y + x * mat.Row0.X + mat.Row0.W;
+	dstVec.Y = z * mat.Row1.Z + y * mat.Row1.Y + x * mat.Row1.X + mat.Row1.W;
+	dstVec.Z = z * mat.Row2.Z + y * mat.Row2.Y + x * mat.Row2.X + mat.Row2.W;
+	return dstVec;
 }
 
-float proj::z_distance(vector3* vec)
+float proj::z_distance(const vector3& vec)
 {
-	vector3 dstVec{};
-	matrix_vector_multiply(&matrix, vec, &dstVec);
-	return maths::magnitude(dstVec);
+	auto projVec = matrix_vector_multiply(matrix, vec);
+	return maths::magnitude(projVec);
 }
 
-void proj::xform_to_2d(vector3* vec, int* dst)
+vector2i proj::xform_to_2d(const vector2& vec)
+{
+	vector3 vec3{ vec.X, vec.Y, 0 };
+	return xform_to_2d(vec3);
+}
+
+vector2i proj::xform_to_2d(const vector3& vec)
 {
 	float projCoef;
-	vector3 dstVec2{};
 
-	matrix_vector_multiply(&matrix, vec, &dstVec2);
-	if (dstVec2.Z == 0.0f)
+	auto projVec = matrix_vector_multiply(matrix, vec);
+	if (projVec.Z == 0.0f)
 		projCoef = 999999.88f;
 	else
-		projCoef = d_ / dstVec2.Z;
-	dst[0] = static_cast<int>(dstVec2.X * projCoef + centerx);
-	dst[1] = static_cast<int>(dstVec2.Y * projCoef + centery);
+		projCoef = d_ / projVec.Z;
+	return
+	{
+		static_cast<int>(projVec.X * projCoef + centerx),
+		static_cast<int>(projVec.Y * projCoef + centery)
+	};
 }
 
 void proj::recenter(float centerX, float centerY)
diff --git a/SpaceCadetPinball/proj.h b/SpaceCadetPinball/proj.h
index e872925..d8cb728 100644
--- a/SpaceCadetPinball/proj.h
+++ b/SpaceCadetPinball/proj.h
@@ -22,9 +22,10 @@ class proj
 {
 public:
 	static void init(float* mat4x3, float d, float centerX, float centerY);
-	static void matrix_vector_multiply(mat4_row_major* mat, vector3* vec, vector3* dstVec);
-	static float z_distance(vector3* vec);
-	static void xform_to_2d(vector3* vec, int* dst);
+	static vector3 matrix_vector_multiply(const mat4_row_major& mat, const vector3& vec);
+	static float z_distance(const vector3& vec);
+	static vector2i xform_to_2d(const vector3& vec);
+	static vector2i xform_to_2d(const vector2& vec);
 	static void recenter(float centerX, float centerY);
 private:
 	static mat4_row_major matrix;
diff --git a/SpaceCadetPinball/render.cpp b/SpaceCadetPinball/render.cpp
index 78c94b5..0a36f96 100644
--- a/SpaceCadetPinball/render.cpp
+++ b/SpaceCadetPinball/render.cpp
@@ -8,6 +8,7 @@
 #include "score.h"
 #include "TPinballTable.h"
 #include "winmain.h"
+#include "DebugOverlay.h"
 
 std::vector<render_sprite_type_struct*> render::dirty_list, render::sprite_list, render::ball_list;
 zmap_header_type* render::background_zmap;
@@ -57,6 +58,7 @@ void render::uninit()
 	ball_list.clear();
 	dirty_list.clear();
 	sprite_list.clear();
+	DebugOverlay::UnInit();
 }
 
 void render::recreate_screen_texture()
@@ -585,4 +587,9 @@ void render::PresentVScreen()
 		SDL_RenderCopy(winmain::Renderer, vscreen->Texture, &srcSidebarRect, &dstSidebarRect);
 #endif
 	}
+
+	if (options::Options.DebugOverlay)
+	{
+		DebugOverlay::DrawOverlay();
+	}
 }
diff --git a/SpaceCadetPinball/winmain.cpp b/SpaceCadetPinball/winmain.cpp
index 12e5d1a..89e233a 100644
--- a/SpaceCadetPinball/winmain.cpp
+++ b/SpaceCadetPinball/winmain.cpp
@@ -577,6 +577,24 @@ void winmain::RenderUi()
 			{
 				DispGRhistory ^= true;
 			}
+			if (ImGui::MenuItem("Debug Overlay", nullptr, Options.DebugOverlay))
+			{
+				Options.DebugOverlay ^= true;
+			}
+			if (Options.DebugOverlay && ImGui::BeginMenu("Overlay Options"))
+			{
+				if (ImGui::MenuItem("Box Grid", nullptr, Options.DebugOverlayGrid))
+					Options.DebugOverlayGrid ^= true;
+				if (ImGui::MenuItem("All Edges", nullptr, Options.DebugOverlayAllEdges))
+					Options.DebugOverlayAllEdges ^= true;
+				if (ImGui::MenuItem("Ball Position", nullptr, Options.DebugOverlayBallPosition))
+					Options.DebugOverlayBallPosition ^= true;
+				if (ImGui::MenuItem("Ball Box Edges", nullptr, Options.DebugOverlayBallEdges))
+					Options.DebugOverlayBallEdges ^= true;
+				if (ImGui::MenuItem("Apply Collision Mask", nullptr, Options.DebugOverlayCollisionMask))
+					Options.DebugOverlayCollisionMask ^= true;
+				ImGui::EndMenu();
+			}
 			if (ImGui::BeginMenu("Cheats"))
 			{
 				if (ImGui::MenuItem("hidden test", nullptr, pb::cheat_mode))