diff --git a/Doc/FuncStats.xlsx b/Doc/FuncStats.xlsx
index b5acbe9..ea9f0bd 100644
Binary files a/Doc/FuncStats.xlsx and b/Doc/FuncStats.xlsx differ
diff --git a/SpaceCadetPinball/loader.cpp b/SpaceCadetPinball/loader.cpp
index fb7ba3b..0daf74f 100644
--- a/SpaceCadetPinball/loader.cpp
+++ b/SpaceCadetPinball/loader.cpp
@@ -451,8 +451,8 @@ int  loader::query_visual(int groupIndex, int groupIndexOffset, visualStruct* vi
 	visual->ZMap = bitmap16;
 	if (bitmap16)
 	{
-		bitmap16->BmpBufPtr1 = bitmap16->BmpBuffer;
-		visual->ZMap->bmpBufPtr2 = visual->ZMap->BmpBufPtr1;
+		bitmap16->ZPtr1 = bitmap16->ZBuffer;
+		visual->ZMap->ZPtr2 = visual->ZMap->ZPtr1;
 	}
 	shortArr = (__int16*)partman::field(loader_table, groupIndexSum2, datFieldTypes::ShortArray);
 	if (shortArr)
diff --git a/SpaceCadetPinball/memory.h b/SpaceCadetPinball/memory.h
index d7e4a50..e42d53c 100644
--- a/SpaceCadetPinball/memory.h
+++ b/SpaceCadetPinball/memory.h
@@ -11,3 +11,12 @@ public:
 	static int critical_allocation;
 	static void (*critical_callback)();
 };
+
+
+// Fill memory block with an integer value
+inline void memset32(void* ptr, unsigned int value, int count)
+{
+	auto p = (unsigned int*)ptr;
+	for (int i = 0; i < count; i++)
+		*p++ = value;
+}
\ No newline at end of file
diff --git a/SpaceCadetPinball/render.h b/SpaceCadetPinball/render.h
index 78c85ed..f56fcc1 100644
--- a/SpaceCadetPinball/render.h
+++ b/SpaceCadetPinball/render.h
@@ -20,8 +20,7 @@ struct __declspec(align(4)) render_sprite_type_struct
 	zmap_header_type* ZMap;
 	char Unknown6_0;
 	VisualType VisualType;
-	char Unknown6_2;
-	char Unknown6_3;
+	short Depth;
 	int XPosition2;
 	int YPosition2;
 	int Bmp8Width2;
@@ -37,6 +36,8 @@ struct __declspec(align(4)) render_sprite_type_struct
 	visual_rect Rect;
 };
 
+static_assert(sizeof(render_sprite_type_struct) == 0x5c, "Wrong size render_sprite_type_struct");
+
 class render
 {
 public:
diff --git a/SpaceCadetPinball/zdrv.cpp b/SpaceCadetPinball/zdrv.cpp
index 01f2c4d..8abcb7c 100644
--- a/SpaceCadetPinball/zdrv.cpp
+++ b/SpaceCadetPinball/zdrv.cpp
@@ -1,2 +1,122 @@
 #include "pch.h"
 #include "zdrv.h"
+#include "memory.h"
+
+
+int zdrv::create_zmap(zmap_header_type* zmap, int width, int height)
+{
+	int stride = pad(width);
+	zmap->Stride = stride;
+	auto bmpBuf = (unsigned short*)memory::allocate(2 * height * stride);
+	zmap->ZPtr1 = bmpBuf;
+	if (!bmpBuf)
+		return -1;
+	zmap->ZPtr2 = bmpBuf;
+	zmap->Width = width;
+	zmap->Height = height;
+	return 0;
+}
+
+int zdrv::pad(int width)
+{
+	int result = width;
+	if (width & 3)
+		result = width - (width & 3) + 4;
+	return result;
+}
+
+int zdrv::destroy_zmap(zmap_header_type* zmap)
+{
+	if (!zmap)
+		return -1;
+	if (zmap->ZPtr1)
+		memory::free(zmap->ZPtr1);
+	zmap->Width = 0;
+	zmap->Height = 0;
+	zmap->Stride = 0;
+	zmap->ZPtr1 = nullptr;
+	zmap->ZPtr2 = nullptr;
+	return 0;
+}
+
+void zdrv::fill(zmap_header_type* zmap, int width, int height, int xOff, int yOff, __int16 fillChar)
+{
+	int fillCharInt = fillChar | (fillChar << 16);
+	auto zmapPtr = &zmap->ZPtr1[2 * (xOff + zmap->Stride * (zmap->Height - height - yOff))];
+
+	for (int y = height; width > 0 && y > 0; y--)
+	{
+		char widthMod2 = width & 1;
+		unsigned int widthDiv2 = static_cast<unsigned int>(width) >> 1;
+		memset32(zmapPtr, fillCharInt, widthDiv2);
+
+		__int16* lastShort = (__int16*)&zmapPtr[2 * widthDiv2];
+		for (int i = widthMod2; i; --i)
+			*lastShort++ = fillChar;
+
+		zmapPtr += zmap->Stride;
+	}
+}
+
+
+void zdrv::paint(int width, int height, gdrv_bitmap8* dstBmp, int dstBmpXOff, int dstBmpYOff, zmap_header_type* dstZMap,
+                 int dstZMapXOff, int dstZMapYOff, gdrv_bitmap8* srcBmp, int srcBmpXOff, int srcBmpYOff,
+                 zmap_header_type* srcZMap, int srcZMapXOff, int srcZMapYOff)
+{
+	int dstHeightAbs = abs(dstBmp->Height);
+	int srcHeightAbs = abs(srcBmp->Height);
+	auto srcPtr = &srcBmp->BmpBufPtr1[srcBmp->Stride * (srcHeightAbs - height - srcBmpYOff) + srcBmpXOff];
+	auto dstPtr = &dstBmp->BmpBufPtr1[dstBmp->Stride * (dstHeightAbs - height - dstBmpYOff) + dstBmpXOff];
+	auto srcPtrZ = &srcZMap->ZPtr1[srcZMap->Stride * (srcZMap->Height - height - srcZMapYOff) + srcZMapXOff];
+	auto dstPtrZ = &dstZMap->ZPtr1[dstZMap->Stride * (dstZMap->Height - height - dstZMapYOff) + dstZMapXOff];
+
+	for (int y = height; y > 0; y--)
+	{
+		for (int x = width; x > 0; --x)
+		{
+			if (*dstPtrZ >= *srcPtrZ)
+			{
+				*dstPtr = *srcPtr;
+				*dstPtrZ = *srcPtrZ;
+			}
+			++srcPtr;
+			++dstPtr;
+			++srcPtrZ;
+			++dstPtrZ;
+		}
+
+		srcPtr += srcBmp->Stride - width;
+		dstPtr += dstBmp->Stride - width;
+		srcPtrZ += srcZMap->Stride - width;
+		dstPtrZ += dstZMap->Stride - width;
+	}
+}
+
+void zdrv::paint_flat(int width, int height, gdrv_bitmap8* dstBmp, int dstBmpXOff, int dstBmpYOff,
+                      zmap_header_type* zMap, int dstZMapXOff, int dstZMapYOff, gdrv_bitmap8* srcBmp, int srcBmpXOff,
+                      int srcBmpYOff, unsigned __int16 depth)
+{
+	int dstHeightAbs = abs(dstBmp->Height);
+	int srcHeightAbs = abs(srcBmp->Height);
+	auto dstPtr = &dstBmp->BmpBufPtr1[dstBmp->Stride * (dstHeightAbs - height - dstBmpYOff) + dstBmpXOff];
+	auto srcPtr = &srcBmp->BmpBufPtr1[srcBmp->Stride * (srcHeightAbs - height - srcBmpYOff) + srcBmpXOff];
+	auto zPtr = &zMap->ZPtr1[zMap->Stride * (zMap->Height - height - dstZMapYOff) + dstZMapXOff];
+
+	for (int y = height; y > 0; y--)
+	{
+		for (int x = width; x > 0; --x)
+		{
+			if (*srcPtr && *zPtr > depth)
+			{
+				*dstPtr = *srcPtr;
+			}
+			++srcPtr;
+			++dstPtr;
+			++zPtr;
+		}
+
+		srcPtr += srcBmp->Stride - width;
+		dstPtr += dstBmp->Stride - width;
+		zPtr += zMap->Stride - width;
+	}
+}
diff --git a/SpaceCadetPinball/zdrv.h b/SpaceCadetPinball/zdrv.h
index cd26bdf..92d23ce 100644
--- a/SpaceCadetPinball/zdrv.h
+++ b/SpaceCadetPinball/zdrv.h
@@ -1,4 +1,5 @@
 #pragma once
+#include "gdrv.h"
 
 #pragma pack(push, 1)
 struct __declspec(align(1)) zmap_header_type
@@ -6,17 +7,26 @@ struct __declspec(align(1)) zmap_header_type
 	__int16 Width;
 	__int16 Height;
 	__int16 Stride;
-	char* BmpBufPtr1;
-	char* bmpBufPtr2;
-	char BmpBuffer[1];
+	unsigned __int16* ZPtr1;
+	unsigned __int16* ZPtr2;
+	unsigned __int16 ZBuffer[1];
 };
+
 #pragma pack(pop)
 
-static_assert(sizeof(zmap_header_type) == 15, "Wrong size of zmap_header_type");
+static_assert(sizeof(zmap_header_type) == 16, "Wrong size of zmap_header_type");
 
 class zdrv
 {
 public:
-	
+	static int pad(int width);
+	static int create_zmap(zmap_header_type* zmap, int width, int height);
+	static int destroy_zmap(zmap_header_type* zmap);
+	static void fill(zmap_header_type* zmap, int width, int height, int xOff, int yOff, __int16 fillChar);
+	static void paint(int width, int height, gdrv_bitmap8* dstBmp, int dstBmpXOff, int dstBmpYOff,
+	                  zmap_header_type* dstZMap, int dstZMapXOff, int dstZMapYOff, gdrv_bitmap8* srcBmp, int srcBmpXOff,
+	                  int srcBmpYOff, zmap_header_type* srcZMap, int srcZMapXOff, int srcZMapYOff);
+	static void paint_flat(int width, int height, gdrv_bitmap8* dstBmp, int dstBmpXOff, int dstBmpYOff,
+	                       zmap_header_type* zMap, int dstZMapXOff, int dstZMapYOff, gdrv_bitmap8* srcBmp,
+	                       int srcBmpXOff, int srcBmpYOff, unsigned __int16 depth);
 };
-