diff --git a/librtt/Display/Rtt_ClosedPath.cpp b/librtt/Display/Rtt_ClosedPath.cpp
index cd3c9e508..ad3033eaa 100644
--- a/librtt/Display/Rtt_ClosedPath.cpp
+++ b/librtt/Display/Rtt_ClosedPath.cpp
@@ -16,6 +16,8 @@
 #include "Display/Rtt_Shader.h"
 #include "Renderer/Rtt_Program.h"
 
+#include "Display/Rtt_CompositePaint.h"
+
 // ----------------------------------------------------------------------------
 
 namespace Rtt
@@ -79,12 +81,37 @@ ClosedPath::SetSelfBounds( Real width, Real height )
 	return false;
 }
 
+static bool
+ComesFromImageSheet( const Paint* paint )
+{
+	if ( paint->IsType( Paint::kImageSheet ) )
+	{
+		return true;
+	}
+	
+	if ( !paint->IsType( Paint::kMultitexture ) )
+	{
+		return false;
+	}
+	
+	const CompositePaint* composite = static_cast< const CompositePaint* >( paint );
+	
+	if ( composite->GetPaint0() && composite->GetPaint0()->IsType( Paint::kImageSheet ) )
+	{
+		return true;
+	}
+	 
+	return false;
+}
+
 void
 ClosedPath::UpdatePaint( RenderData& data )
 {
 	if ( HasFill() )
 	{
 		fFill->UpdatePaint( data );
+
+		data.fFromImageSheet = ComesFromImageSheet( fFill );
 	}
 
 	if ( HasStroke() && fStrokeData )
diff --git a/librtt/Display/Rtt_CompositePaint.h b/librtt/Display/Rtt_CompositePaint.h
index f03489bbd..b924a7118 100755
--- a/librtt/Display/Rtt_CompositePaint.h
+++ b/librtt/Display/Rtt_CompositePaint.h
@@ -36,6 +36,8 @@ class CompositePaint : public Paint
 	public:
 		virtual const Paint* AsPaint( Type t ) const;
 		virtual void ApplyPaintUVTransformations( ArrayVertex2& vertices ) const override;
+		
+		const Paint* GetPaint0() const { return fPaint0; }
 
 //		virtual const MLuaUserdataAdapter& GetAdapter() const;
 
diff --git a/librtt/Display/Rtt_DisplayDefaults.cpp b/librtt/Display/Rtt_DisplayDefaults.cpp
index 68d01bf3b..882e3b494 100644
--- a/librtt/Display/Rtt_DisplayDefaults.cpp
+++ b/librtt/Display/Rtt_DisplayDefaults.cpp
@@ -52,6 +52,7 @@ DisplayDefaults::DisplayDefaults()
 	fIsImageSheetSampledInsideFrame( false ),
 	fIsImageSheetFrameTrimCorrected( false ),
 	fIsExternalTextureRetina( true ),
+	fIsUnitRegionWantedForBuiltinEffects( false ),
     fSkipsCull( false ),
     fSkipsHitTest( false ),
     fEnableDepthInScene( false ),
diff --git a/librtt/Display/Rtt_DisplayDefaults.h b/librtt/Display/Rtt_DisplayDefaults.h
index 5542efb38..220c3f42e 100644
--- a/librtt/Display/Rtt_DisplayDefaults.h
+++ b/librtt/Display/Rtt_DisplayDefaults.h
@@ -63,15 +63,18 @@ class DisplayDefaults
 		U8 GetEmitterMapping() const { return fEmitterMapping; }
 		void SetEmitterMapping( U8 newValue ) { fEmitterMapping = newValue; }
 
-		bool IsImageSheetSampledInsideFrame() const { return fIsImageSheetSampledInsideFrame;}
+		bool IsImageSheetSampledInsideFrame() const { return fIsImageSheetSampledInsideFrame; }
 		void SetImageSheetSampledInsideFrame( bool newValue ) { fIsImageSheetSampledInsideFrame = newValue; }
 
-		bool IsImageSheetFrameTrimCorrected() const { return fIsImageSheetFrameTrimCorrected;}
+		bool IsImageSheetFrameTrimCorrected() const { return fIsImageSheetFrameTrimCorrected; }
 		void SetImageSheetFrameTrimCorrected( bool newValue ) { fIsImageSheetFrameTrimCorrected = newValue; }
 
-    bool IsExternalTextureRetina() const { return fIsExternalTextureRetina;}
+		bool IsExternalTextureRetina() const { return fIsExternalTextureRetina; }
 		void SetExternalTextureRetina( bool newValue ) { fIsExternalTextureRetina = newValue; }
 
+		bool IsUnitRegionWantedForBuiltinEffects() const { return fIsUnitRegionWantedForBuiltinEffects; }
+		void SetIsUnitRegionWantedForBuiltinEffects( bool newValue ) { fIsUnitRegionWantedForBuiltinEffects = newValue; }
+
 	public:
 		bool IsV1Compatibility() const { return fV1Compatibility; }
 		void SetV1Compatibility( bool newValue ) { fV1Compatibility = newValue; }
@@ -144,6 +147,7 @@ class DisplayDefaults
         bool fIsImageSheetSampledInsideFrame;
 		bool fIsImageSheetFrameTrimCorrected;
 		bool fIsExternalTextureRetina;
+		bool fIsUnitRegionWantedForBuiltinEffects;
         bool fSkipsCull;
         bool fSkipsHitTest;
         bool fEnableDepthInScene;
diff --git a/librtt/Display/Rtt_DisplayObject.cpp b/librtt/Display/Rtt_DisplayObject.cpp
index 1dd4cc820..18716eafc 100644
--- a/librtt/Display/Rtt_DisplayObject.cpp
+++ b/librtt/Display/Rtt_DisplayObject.cpp
@@ -225,6 +225,9 @@ DisplayObject::DidChangePaint( RenderData& data )
     data.fUserUniform1 = NULL;
     data.fUserUniform2 = NULL;
     data.fUserUniform3 = NULL;
+    
+	data.fFromImageSheet = false;
+	data.fWantsUnitRegion = false;
 }
 
 // ----------------------------------------------------------------------------
diff --git a/librtt/Display/Rtt_LuaLibDisplay.cpp b/librtt/Display/Rtt_LuaLibDisplay.cpp
index e188edac6..cc1ec4624 100644
--- a/librtt/Display/Rtt_LuaLibDisplay.cpp
+++ b/librtt/Display/Rtt_LuaLibDisplay.cpp
@@ -1977,6 +1977,11 @@ DisplayLibrary::getDefault( lua_State *L )
 		bool value = defaults.IsExternalTextureRetina();
 		lua_pushboolean( L, value ? 1 : 0 );
 	}
+	else if ( ( Rtt_StringCompare( key, "isUnitRegionWantedForBuiltinEffects" ) == 0 ) )
+	{
+		bool value = defaults.IsUnitRegionWantedForBuiltinEffects();
+		lua_pushboolean( L, value ? 1 : 0 );
+	}
     else if ( ( Rtt_StringCompare( key, "timeTransform" ) == 0 ) )
     {
         const TimeTransform* transform = defaults.GetTimeTransform();
@@ -2169,6 +2174,11 @@ DisplayLibrary::setDefault( lua_State *L )
 		bool value = lua_toboolean( L, index ) ? true : false;
 		defaults.SetExternalTextureRetina( value );
 	}
+	else if ( ( Rtt_StringCompare( key, "isUnitRegionWantedForBuiltinEffects" ) == 0 ) )
+	{
+		bool value = lua_toboolean( L, index ) ? true : false;
+		defaults.SetIsUnitRegionWantedForBuiltinEffects( value );
+	}
     else if ( ( Rtt_StringCompare( key, "timeTransform" ) == 0 ) )
     {
         if ( lua_isstring( L, index ) )
diff --git a/librtt/Display/Rtt_Scene.cpp b/librtt/Display/Rtt_Scene.cpp
index 0f280647a..2c3008eb5 100644
--- a/librtt/Display/Rtt_Scene.cpp
+++ b/librtt/Display/Rtt_Scene.cpp
@@ -210,6 +210,8 @@ Scene::Render( Renderer& renderer, PlatformSurface& rTarget, ProfilingEntryRAII*
 
     if ( ! IsValid() )
     {
+		renderer.SetOptInToUnitRegionEncoding( GetDisplay().GetDefaults().IsUnitRegionWantedForBuiltinEffects() );
+    
         const Rtt::Real kMillisecondsPerSecond = 1000.0f;
         Rtt_AbsoluteTime elapsedTime = fOwner.GetElapsedTime();
         Rtt::Real totalTime = Rtt_AbsoluteToMilliseconds( elapsedTime ) / kMillisecondsPerSecond;
@@ -318,6 +320,8 @@ Scene::Render( Renderer& renderer, PlatformSurface& rTarget, DisplayObject& obje
     const StageObject* stage = object.GetStage();
     if ( Rtt_VERIFY( stage == fCurrentStage ) )
     {
+		renderer.SetOptInToUnitRegionEncoding( GetDisplay().GetDefaults().IsUnitRegionWantedForBuiltinEffects() );
+    
         Clear( renderer );
 
         // This function is used to render a specific object in a scene.
diff --git a/librtt/Display/Rtt_Shader.cpp b/librtt/Display/Rtt_Shader.cpp
index dc1670098..b1594dfd1 100644
--- a/librtt/Display/Rtt_Shader.cpp
+++ b/librtt/Display/Rtt_Shader.cpp
@@ -255,6 +255,14 @@ Shader::Prepare( RenderData& objectData, int w, int h, ShaderResource::ProgramMo
 	
 	objectData.fProgram = program;
 
+	ShaderResource::UnitRegionPolicy policy = fResource->GetUnitRegionPolicy();
+	if ( objectData.fFromImageSheet && ShaderResource::kNone != policy )
+	{
+		objectData.fWantsUnitRegion = true;
+		objectData.fAlwaysUseUnitRegion = ShaderResource::kAlways == policy;
+		objectData.fHasDistortion = ShaderResource::k25D == mod;
+	}
+
     const CoronaEffectCallbacks * callbacks = fResource->GetEffectCallbacks();
 
     if (callbacks && callbacks->prepare)
@@ -275,7 +283,9 @@ Shader::Draw( Renderer& renderer, const RenderData& objectData, const GeometryWr
 {
     if ( !renderer.CanAddGeometryWriters() ) // ignore during raw draws
     {
-        renderer.SetGeometryWriters( writers, n );
+		bool encodeUnitRegion = objectData.fWantsUnitRegion &&
+			( objectData.fAlwaysUseUnitRegion || renderer.GetOptInToUnitRegionEncoding() );
+		renderer.SetGeometryWriters( writers, n, encodeUnitRegion, objectData.fHasDistortion );
     }
 
     DrawState state( fResource->GetEffectCallbacks(), fIsDrawing );
diff --git a/librtt/Display/Rtt_ShaderComposite.cpp b/librtt/Display/Rtt_ShaderComposite.cpp
index 0a764f0c4..14cd78be1 100755
--- a/librtt/Display/Rtt_ShaderComposite.cpp
+++ b/librtt/Display/Rtt_ShaderComposite.cpp
@@ -305,7 +305,9 @@ ShaderComposite::Draw( Renderer& renderer, const RenderData& objectData, const G
 {
     if ( !renderer.CanAddGeometryWriters() ) // ignore during raw draws
     {
-        renderer.SetGeometryWriters( writers, n );
+		bool encodeUnitRegion = objectData.fWantsUnitRegion &&
+			( objectData.fAlwaysUseUnitRegion || renderer.GetOptInToUnitRegionEncoding() );
+		renderer.SetGeometryWriters( writers, n, encodeUnitRegion, objectData.fHasDistortion );
     }
 
     DrawState state( fResource->GetEffectCallbacks(), fIsDrawing );
diff --git a/librtt/Display/Rtt_ShaderFactory.cpp b/librtt/Display/Rtt_ShaderFactory.cpp
index cfd4a22c7..192fc10b2 100644
--- a/librtt/Display/Rtt_ShaderFactory.cpp
+++ b/librtt/Display/Rtt_ShaderFactory.cpp
@@ -768,6 +768,22 @@ ShaderFactory::InitializeBindings( lua_State *L, int shaderIndex, const SharedPt
         BindTimeTransform( L, shaderIndex, resource );
     }
 
+	lua_getfield( L, shaderIndex, "wantUnitRegion" );
+	
+	bool forBuiltins = LUA_TSTRING == lua_type( L, -1 ) && Rtt_StringCompare( lua_tostring( L, -1 ), "builtin" ) == 0;
+	
+	if (forBuiltins)
+	{
+		resource->SetUnitRegionPolicy( ShaderResource::kOptIn );
+	}
+	
+	else if ( LUA_TBOOLEAN == lua_type( L, -1 ) && lua_toboolean( L, -1 ) )
+	{
+		resource->SetUnitRegionPolicy( ShaderResource::kAlways );
+	}
+	
+	lua_pop( L, 1 );
+
     bool has_vertex_data = BindVertexDataMap( L, shaderIndex, resource );
     if( has_vertex_data )
     {
diff --git a/librtt/Display/Rtt_ShaderResource.cpp b/librtt/Display/Rtt_ShaderResource.cpp
index 4669a51f8..34b35b8a3 100755
--- a/librtt/Display/Rtt_ShaderResource.cpp
+++ b/librtt/Display/Rtt_ShaderResource.cpp
@@ -268,6 +268,7 @@ ShaderResource::ShaderResource( Program *program, ShaderTypes::Category category
     fDetailsCount( 0U ),
     fShellTransform( NULL ),
 	fTimeTransform( NULL ),
+	fUnitRegionPolicy( kNone ),
 	fUsesUniforms( false ),
 	fUsesTime( false )
 {
@@ -286,6 +287,7 @@ ShaderResource::ShaderResource( Program *program, ShaderTypes::Category category
     fDetailsCount( 0U ),
     fShellTransform( NULL ),
 	fTimeTransform( NULL ),
+	fUnitRegionPolicy( kNone ),
 	fUsesUniforms( false ),
 	fUsesTime( false )
 {
diff --git a/librtt/Display/Rtt_ShaderResource.h b/librtt/Display/Rtt_ShaderResource.h
index 0567f1061..bfc08e6eb 100644
--- a/librtt/Display/Rtt_ShaderResource.h
+++ b/librtt/Display/Rtt_ShaderResource.h
@@ -68,6 +68,15 @@ class ShaderResource
         }
         ProgramMod;
     
+		typedef enum UnitRegionPolicy
+		{
+			kNone	 = 0,
+			kAlways	 = 1,
+			kOptIn	 = 2,
+			kNumUnitRegionPolicies
+		}
+		UnitRegionPolicy;
+    
         typedef std::map< std::string, int > VertexDataMap;
 
         struct UniformData
@@ -98,6 +107,9 @@ class ShaderResource
         bool UsesTime() const { return fUsesTime; }
         void SetUsesTime( bool newValue ) { fUsesTime = newValue; }
     
+		UnitRegionPolicy GetUnitRegionPolicy() const { return fUnitRegionPolicy; }
+		void SetUnitRegionPolicy( UnitRegionPolicy policy ) { fUnitRegionPolicy = policy; }
+    
         const CoronaEffectCallbacks * GetEffectCallbacks() const { return fEffectCallbacks; }
         void SetEffectCallbacks( CoronaEffectCallbacks * callbacks );
         const CoronaShellTransform * GetShellTransform() const { return fShellTransform; }
@@ -157,6 +169,7 @@ class ShaderResource
         std::vector< std::string > fDetailValues;
         U32 fDetailsCount;
         TimeTransform *fTimeTransform;
+        UnitRegionPolicy fUnitRegionPolicy;
         bool fUsesUniforms;
         bool fUsesTime;
 
diff --git a/librtt/Display/Shader/shell_default_gl.lua b/librtt/Display/Shader/shell_default_gl.lua
index cd28a7cbb..62496761a 100644
--- a/librtt/Display/Shader/shell_default_gl.lua
+++ b/librtt/Display/Shader/shell_default_gl.lua
@@ -21,7 +21,18 @@ uniform P_POSITION vec2 u_ContentScale;
 uniform P_POSITION mat4 u_ViewProjectionMatrix;
 
 #define CoronaVertexUserData a_UserData
-#define CoronaTexCoord a_TexCoord.xy
+
+#if WANT_UNIT_REGION
+	// want decoded attributes, but varyings aren't readable in general,
+	// as elaborated below in main()
+	P_UV vec4 g_DecodedCoords; // (x, y) = texcoord, (z, w) = unit coords
+	
+	#define CoronaTexCoord g_DecodedCoords.xy
+	#define CoronaLocalTexCoord g_DecodedCoords.zw
+#else
+	#define CoronaTexCoord a_TexCoord.xy
+	#define CoronaLocalTexCoord CoronaTexCoord
+#endif
 
 #define CoronaTotalTime u_TotalTime
 #define CoronaDeltaTime u_DeltaTime
@@ -67,6 +78,42 @@ varying P_DEFAULT vec4 v_UserData;
 P_POSITION vec2 VertexKernel( P_POSITION vec2 position );
 #endif
 
+#if WANT_UNIT_REGION
+	varying P_UV vec2 v_UnitCoords;
+
+	P_UV vec2 CoronaAuxDecodeTexCoord( P_UV vec2 texCoord )
+	{
+		P_UV vec2 isEncoded = step( vec2( .5 ), abs( texCoord - .5 ) ); // outside [0, 1]?
+		P_UV vec2 whichSide = sign( texCoord ); // if so, -1 (< 0) or +1 (> 1)
+		
+		g_DecodedCoords.zw = mix( texCoord, max( whichSide, 0. ), isEncoded ); // if decoded, 0 or 1
+
+		v_UnitCoords = g_DecodedCoords.zw;
+		
+		// "encoded" points interpret the texcoords like a
+		// (limited) mirrored repeat, so:
+		// 	< 0: -x
+		// 	from 0 to 1: just x (normal, not encoded)
+		// 	> 1: = 2 - x
+		
+		g_DecodedCoords.xy = mix( texCoord, ( whichSide + 1. ) - texCoord, isEncoded );
+		
+		return g_DecodedCoords.xy;
+	}
+	
+	#ifdef TEX_COORD_Z
+		P_UV vec2 CoronaDecodeTexCoord( P_UV vec3 texCoord )
+		{
+			return CoronaAuxDecodeTexCoord( texCoord.xy / texCoord.z ) * texCoord.z;
+		}
+	#else
+		#define CoronaDecodeTexCoord( texCoord ) CoronaAuxDecodeTexCoord( texCoord.xy )
+	#endif
+	
+#else
+	#define CoronaDecodeTexCoord( texCoord ) texCoord.xy
+#endif
+
 void main()
 {
 	// "varying" are only meant as OUTPUT variables. ie: Write-only variables
@@ -76,7 +123,7 @@ void main()
 	// Certain devices, like the "Samsung Galaxy Tab 2", DON'T allow you to
 	// use "varying" variable like any other local variables.
 
-	v_TexCoord = a_TexCoord.xy;
+	v_TexCoord = CoronaDecodeTexCoord( a_TexCoord );
 #ifdef TEX_COORD_Z
 	v_TexCoordZ = a_TexCoord.z;
 #endif
@@ -122,6 +169,13 @@ varying P_DEFAULT vec4 v_UserData;
 #define CoronaColorScale( color ) (v_ColorScale*(color))
 #define CoronaVertexUserData v_UserData
 
+#if WANT_UNIT_REGION
+	varying P_UV vec2 v_UnitCoords;
+	#define CoronaLocalTexCoord( _ ) v_UnitCoords
+#else
+	#define CoronaLocalTexCoord( texCoord ) texCoord
+#endif
+
 #define CoronaTotalTime u_TotalTime
 #define CoronaDeltaTime u_DeltaTime
 #define CoronaTexelSize u_TexelSize
diff --git a/librtt/Renderer/Rtt_GLProgram.cpp b/librtt/Renderer/Rtt_GLProgram.cpp
index 437697979..85c9e96da 100644
--- a/librtt/Renderer/Rtt_GLProgram.cpp
+++ b/librtt/Renderer/Rtt_GLProgram.cpp
@@ -363,8 +363,10 @@ GLProgram::UpdateShaderSource( Program* program, Program::Version version, Versi
     char highp_support[] = "#define FRAGMENT_SHADER_SUPPORTS_HIGHP 0\n";
     highp_support[ sizeof( highp_support ) - 3 ] = ( CommandBuffer::GetGpuSupportsHighPrecisionFragmentShaders() ? '1' : '0' );
 
-    //! \TODO Make the definition of "TEX_COORD_Z" conditional.
-    char texCoordZBuffer[] = "";//#define TEX_COORD_Z 1\n";
+    ShaderResource * shaderResource = program->GetShaderResource();
+    
+    char wantUnitRegionBuffer[] = "#define WANT_UNIT_REGION 0\n";
+	wantUnitRegionBuffer[ sizeof( wantUnitRegionBuffer ) - 3] = ( shaderResource->GetUnitRegionPolicy() != ShaderResource::kNone ? '1' : '0' );
 
     const char *program_header_source = program->GetHeaderSource();
     const char *header = ( program_header_source ? program_header_source : "" );
@@ -374,7 +376,7 @@ GLProgram::UpdateShaderSource( Program* program, Program::Version version, Versi
     shader_source[0] = header;
     shader_source[1] = highp_support;
     shader_source[2] = maskBuffer;
-    shader_source[3] = texCoordZBuffer;
+    shader_source[3] = wantUnitRegionBuffer;
 
     if ( program->IsCompilerVerbose() )
     {
@@ -383,10 +385,9 @@ GLProgram::UpdateShaderSource( Program* program, Program::Version version, Versi
         data.fHeaderNumLines = CountLines( shader_source, numSegments );
     }
     
-    ShaderResource * shaderResource = program->GetShaderResource();
     const CoronaShellTransform * shellTransform = shaderResource->GetShellTransform();
     CoronaShellTransformParams params = {};
-    const char * hints[] = { "header", "highpSupport", "mask", "texCoordZ", NULL };
+    const char * hints[] = { "header", "highpSupport", "mask", "wantUnitRegion", NULL };
     void * shellTransformKey = &fCleanupShellTransform; // n.b. done to make cleanup robust
 
     std::vector< CoronaEffectDetail > details;
diff --git a/librtt/Renderer/Rtt_Geometry_Renderer.cpp b/librtt/Renderer/Rtt_Geometry_Renderer.cpp
index 96e292d0f..779bde8d5 100644
--- a/librtt/Renderer/Rtt_Geometry_Renderer.cpp
+++ b/librtt/Renderer/Rtt_Geometry_Renderer.cpp
@@ -53,6 +53,127 @@ GeometryWriter::CopyGeometryWriter()
     return sCopyGeometry;
 }
 
+static float GetFloat( const void* bytes )
+{
+	return *static_cast< const float* >( bytes );
+}
+
+static float GetFloatMappedTo0( const void* bytes )
+{
+	float f = GetFloat( bytes );
+
+	return f > 0.f ? -f : 0.f;
+}
+
+static float GetFloatMappedTo1( const void* bytes )
+{
+	float f = GetFloat( bytes );
+
+	return f < 1.f ? 2. - f : 1.f;
+}
+
+static void CopyFloat( void* dst, const float f )
+{
+	memcpy( dst, &f, sizeof(float) );
+}
+
+void
+GeometryWriter::UnitRegionEncode( void* dst, const void* src, const CoronaGeometryMappingLayout* layout, U32, U32 n )
+{
+	Rtt_ASSERT( 4 == n ); // specialization for image sheet rects
+
+	unsigned char * bytes = static_cast<unsigned char *>( dst );
+
+	// Bottom-left
+	float leftX = GetFloatMappedTo0( bytes );
+	float bottomY = GetFloatMappedTo0( bytes + sizeof(float) );
+
+	CopyFloat( bytes, leftX );
+	CopyFloat( bytes + sizeof(float), bottomY );
+
+	bytes += layout->outStride;
+	
+	// Upper-left
+	float topY = GetFloatMappedTo1( bytes + sizeof(float) );
+
+	CopyFloat( bytes, leftX );
+	CopyFloat( bytes + sizeof(float), topY );
+	
+	bytes += layout->outStride;
+	
+	// Bottom-right
+	float rightX = GetFloatMappedTo1( bytes );
+	
+	CopyFloat( bytes, rightX );
+	CopyFloat( bytes + sizeof(float), bottomY );
+	
+	bytes += layout->outStride;
+
+	// Upper-right
+	CopyFloat( bytes, rightX );
+	CopyFloat( bytes + sizeof(float), topY );
+}
+
+static float MapDistortedFloatTo0( float f, float z )
+{
+/*
+	float raw = f / z, encoded = -raw;
+
+	return encoded * z;
+*/
+	return -f;
+}
+
+static float MapDistortedFloatTo1( float f, float z )
+{
+/*
+	float raw = f / z, encoded = 2.f - raw;
+
+	return encoded * z;
+*/
+	return 2.f * z - f;
+}
+
+static void GetFloatTriple( unsigned char* bytes, float xyz[] )
+{
+	memcpy( xyz, bytes, 3 * sizeof(float) );
+}
+
+void
+GeometryWriter::UnitRegionEncodeWithDistortion( void* dst, const void* src, const CoronaGeometryMappingLayout* layout, U32, U32 n )
+{
+	Rtt_ASSERT( 4 == n ); // specialization for image sheet rects
+
+	unsigned char * bytes = static_cast<unsigned char *>( dst );
+	float xyz[3];
+
+	// Bottom-left
+	GetFloatTriple( bytes, xyz );
+	CopyFloat( bytes, MapDistortedFloatTo0( xyz[0], xyz[2] ) );
+	CopyFloat( bytes + sizeof(float), MapDistortedFloatTo0( xyz[1], xyz[2] ) );
+	
+	bytes += layout->outStride;
+	
+	// Upper-left
+	GetFloatTriple( bytes, xyz );
+	CopyFloat( bytes, MapDistortedFloatTo0( xyz[0], xyz[2] ) );
+	CopyFloat( bytes + sizeof(float), MapDistortedFloatTo1( xyz[1], xyz[2] ) );
+
+	bytes += layout->outStride;
+
+	// Bottom-right
+	GetFloatTriple( bytes, xyz );
+	CopyFloat( bytes, MapDistortedFloatTo1( xyz[0], xyz[2] ) );
+	CopyFloat( bytes + sizeof(float), MapDistortedFloatTo0( xyz[1], xyz[2] ) );
+	
+	bytes += layout->outStride;
+	
+	// Upper-right
+	GetFloatTriple( bytes, xyz );
+	CopyFloat( bytes, MapDistortedFloatTo1( xyz[0], xyz[2] ) );
+	CopyFloat( bytes + sizeof(float), MapDistortedFloatTo1( xyz[1], xyz[2] ) );
+}
+
 void Geometry::Vertex::Zero()
 {
     memset(this, 0, sizeof(*this));
diff --git a/librtt/Renderer/Rtt_Geometry_Renderer.h b/librtt/Renderer/Rtt_Geometry_Renderer.h
index 0663992d6..662ab8441 100644
--- a/librtt/Renderer/Rtt_Geometry_Renderer.h
+++ b/librtt/Renderer/Rtt_Geometry_Renderer.h
@@ -71,6 +71,9 @@ struct GeometryWriter {
     Rtt_STATIC_ASSERT( ( kExtra == kMain + 1 ) && ( kIsUpdate == kAll + 1 ) );
 
     static const GeometryWriter& CopyGeometryWriter();
+    
+    static void UnitRegionEncode( void* dst, const void* src, const CoronaGeometryMappingLayout* layout, U32, U32 n );
+    static void UnitRegionEncodeWithDistortion( void* dst, const void* src, const CoronaGeometryMappingLayout* layout, U32, U32 n );
 
 	const void* fContext;
 	void (*fWriter)( void*, const void*, const CoronaGeometryMappingLayout*, U32, U32 );
diff --git a/librtt/Renderer/Rtt_RenderData.cpp b/librtt/Renderer/Rtt_RenderData.cpp
index 800e43b71..a30903bcd 100644
--- a/librtt/Renderer/Rtt_RenderData.cpp
+++ b/librtt/Renderer/Rtt_RenderData.cpp
@@ -36,7 +36,11 @@ RenderData::RenderData()
 //	fMinDepthRange( 0.0 ),
 //	fMaxDepthRange( 1.0 ),
 	fBlendMode(),
-	fBlendEquation( RenderTypes::kAddEquation )
+	fBlendEquation( RenderTypes::kAddEquation ),
+	fFromImageSheet( false ),
+	fWantsUnitRegion( false ),
+	fAlwaysUseUnitRegion( false ),
+	fHasDistortion( false )
 {
 }
 
diff --git a/librtt/Renderer/Rtt_RenderData.h b/librtt/Renderer/Rtt_RenderData.h
index 00bd30134..8211f0dcd 100644
--- a/librtt/Renderer/Rtt_RenderData.h
+++ b/librtt/Renderer/Rtt_RenderData.h
@@ -50,6 +50,12 @@ struct RenderData
 //	Real fMaxDepthRange;
 	BlendMode fBlendMode;
 	RenderTypes::BlendEquation fBlendEquation;
+	
+	// for unit region mechanics:
+	bool fFromImageSheet;
+	bool fWantsUnitRegion;
+	bool fAlwaysUseUnitRegion;
+	bool fHasDistortion;
 };
 
 // ----------------------------------------------------------------------------
diff --git a/librtt/Renderer/Rtt_Renderer.cpp b/librtt/Renderer/Rtt_Renderer.cpp
index 419d78150..58de9d0e5 100644
--- a/librtt/Renderer/Rtt_Renderer.cpp
+++ b/librtt/Renderer/Rtt_Renderer.cpp
@@ -1281,12 +1281,12 @@ Renderer::IssueCaptures( Texture * fill0 )
 }
 
 void
-Renderer::SetGeometryWriters( const GeometryWriter* list, U32 n )
+Renderer::SetGeometryWriters( const GeometryWriter* list, U32 n, bool wantUnitRegion, bool hasDistortion )
 {
     if ( 0 == n || list != fCurrentGeometryWriterList )
     {
         fGeometryWriters.Clear();
-
+ 
         if ( NULL == list )
         {
             list = &GeometryWriter::CopyGeometryWriter();
@@ -1308,6 +1308,27 @@ Renderer::SetGeometryWriters( const GeometryWriter* list, U32 n )
 
         Rtt_ASSERT( GeometryWriter::kAll == mask );
 
+		if (wantUnitRegion)
+		{
+			GeometryWriter encode = {};
+			
+			encode.fOffset = offsetof(Geometry::Vertex, u);
+			
+			if (hasDistortion)
+			{
+				encode.fWriter = GeometryWriter::UnitRegionEncodeWithDistortion;
+			}
+			
+			else
+			{
+				encode.fWriter = GeometryWriter::UnitRegionEncode;
+			}
+			
+			encode.fMask = GeometryWriter::kTexcoord;
+			
+			fGeometryWriters.Append( encode );
+		}
+
         fCurrentGeometryWriterList = list;
     }
 }
diff --git a/librtt/Renderer/Rtt_Renderer.h b/librtt/Renderer/Rtt_Renderer.h
index dc34e4beb..b21d13d22 100644
--- a/librtt/Renderer/Rtt_Renderer.h
+++ b/librtt/Renderer/Rtt_Renderer.h
@@ -259,7 +259,7 @@ class Renderer
 		void IssueCaptures( Texture * fill0 );
 
     public:
-        void SetGeometryWriters( const GeometryWriter* list, U32 n = 1 );
+        void SetGeometryWriters( const GeometryWriter* list, U32 n = 1, bool wantUnitRegion = false, bool hasDistortion = false );
         bool AddGeometryWriter( const GeometryWriter& writer, bool isUpdate );
         bool CanAddGeometryWriters() const { return fCanAddGeometryWriters; }
 
@@ -270,6 +270,10 @@ class Renderer
             Renderer& fRenderer;
         };
         
+	public:
+		bool GetOptInToUnitRegionEncoding() const { return fOptInToUnitRegionEncoding; }
+		void SetOptInToUnitRegionEncoding( bool newValue ) { fOptInToUnitRegionEncoding = newValue; }
+        
     protected:
 	    void WriteGeometry ( void * dstGeomComp, const void* srcGeom, U32 stride, U32 index, U32 count = 1, GeometryWriter::MaskBits validBits = GeometryWriter::kMain );
 
@@ -411,6 +415,7 @@ class Renderer
         Array< GeometryWriter > fGeometryWriters;
         const GeometryWriter* fCurrentGeometryWriterList; // to detect change in writer; assumed to be stable object, i.e. either NULL (default) or some static array
         bool fCanAddGeometryWriters;
+        bool fOptInToUnitRegionEncoding;
 };
 
 // ----------------------------------------------------------------------------