diff --git a/src/Graphics/OpenGLContext/GLSL/glsl_CombinerProgramBuilder.cpp b/src/Graphics/OpenGLContext/GLSL/glsl_CombinerProgramBuilder.cpp
index f266b502..659eb703 100644
--- a/src/Graphics/OpenGLContext/GLSL/glsl_CombinerProgramBuilder.cpp
+++ b/src/Graphics/OpenGLContext/GLSL/glsl_CombinerProgramBuilder.cpp
@@ -1,3 +1,4 @@
+#include <iomanip> // for setprecision
 #include <assert.h>
 #include <Log.h>
 #include <Config.h>
@@ -7,6 +8,7 @@
 #include "glsl_CombinerProgramImpl.h"
 #include "glsl_CombinerProgramBuilder.h"
 #include "glsl_CombinerProgramUniformFactory.h"
+#include "GraphicsDrawer.h"
 
 using namespace glsl;
 
@@ -268,6 +270,9 @@ public:
 			m_part = ss.str();
 		}
 		m_part += "uniform lowp vec2 uVertexOffset; \n";
+		std::stringstream ss;
+		ss << "const lowp float screenSizeDims = " << std::setprecision(1) << std::fixed << SCREEN_SIZE_DIM << ";" << std::endl;
+		m_part += ss.str();
 	}
 };
 
@@ -513,8 +518,9 @@ public:
 			m_part = "  gl_Position.z /= 8.0;	\n";
 		}
 		m_part +=
-			" gl_Position.xy += uVertexOffset * vec2(gl_Position.w); \n"
-			" gl_Position.zw *= vec2(1024.0);		 \n"
+			" gl_Position.xy += uVertexOffset * vec2(gl_Position.w);		\n"
+			" gl_Position.xy -= vec2(0.5*screenSizeDims) * gl_Position.ww;	\n"
+			" gl_Position.xy /= vec2(0.5*screenSizeDims);					\n"
 			"} \n"
 			;
 	}
diff --git a/src/Graphics/OpenGLContext/GLSL/glsl_ShaderStorage.h b/src/Graphics/OpenGLContext/GLSL/glsl_ShaderStorage.h
index a6d573b5..50a9ded7 100644
--- a/src/Graphics/OpenGLContext/GLSL/glsl_ShaderStorage.h
+++ b/src/Graphics/OpenGLContext/GLSL/glsl_ShaderStorage.h
@@ -20,7 +20,7 @@ namespace glsl {
 		bool _saveCombinerKeys(const graphics::Combiners & _combiners) const;
 		bool _loadFromCombinerKeys(graphics::Combiners & _combiners);
 
-		const u32 m_formatVersion = 0x34U;
+		const u32 m_formatVersion = 0x35U;
 		const u32 m_keysFormatVersion = 0x05;
 		const opengl::GLInfo & m_glinfo;
 		opengl::CachedUseProgram * m_useProgram;
diff --git a/src/GraphicsDrawer.cpp b/src/GraphicsDrawer.cpp
index baccfcbb..9f5a1694 100644
--- a/src/GraphicsDrawer.cpp
+++ b/src/GraphicsDrawer.cpp
@@ -253,10 +253,10 @@ void GraphicsDrawer::_updateViewport(const FrameBuffer* _pBuffer, const f32 scal
 	} else {
 		scaleX = scaleY = scale;
 	}
-	X = roundup(-1024.0f, scaleX);
-	Y = roundup(-1024.0f, scaleY);
-	WIDTH = roundup(2048.0f, scaleX);
-	HEIGHT = roundup(2048.0f, scaleY);
+	X = 0;
+	Y = 0;
+	WIDTH = roundup(SCREEN_SIZE_DIM, scaleX);
+	HEIGHT = roundup(SCREEN_SIZE_DIM, scaleY);
 	gfxContext.setViewport(X, Y, WIDTH, HEIGHT);
 	gSP.changed |= CHANGED_VIEWPORT;
 }
diff --git a/src/GraphicsDrawer.h b/src/GraphicsDrawer.h
index 87f432ac..d1c479e8 100644
--- a/src/GraphicsDrawer.h
+++ b/src/GraphicsDrawer.h
@@ -20,6 +20,8 @@ struct FrameBuffer;
 #define VERTBUFF_SIZE 256U
 #define ELEMBUFF_SIZE 1024U
 
+constexpr f32 SCREEN_SIZE_DIM = 640.0f;
+
 enum class DrawingState
 {
 	Non,
diff --git a/src/TexrectDrawer.cpp b/src/TexrectDrawer.cpp
index 6421c97d..4a64915e 100644
--- a/src/TexrectDrawer.cpp
+++ b/src/TexrectDrawer.cpp
@@ -380,8 +380,13 @@ bool TexrectDrawer::draw()
 	const float t0 = m_lry / (float)m_pTexture->height;// +0.5f / (float)m_pTexture->height;
 	const float s1 = m_lrx / (float)m_pTexture->width;
 	const float t1 = m_uly / (float)m_pTexture->height;
-	const float W = 1024.0f;
-	const float Z = m_Z * 1024.0f;
+	const float W = 1.0f;
+	const float Z = m_Z;
+	constexpr float halfScreenSizeDims = SCREEN_SIZE_DIM * 0.5f;
+	m_ulx = (m_ulx - halfScreenSizeDims) / halfScreenSizeDims;
+	m_uly = (m_uly - halfScreenSizeDims) / halfScreenSizeDims;
+	m_lrx = (m_lrx - halfScreenSizeDims) / halfScreenSizeDims;
+	m_lry = (m_lry - halfScreenSizeDims) / halfScreenSizeDims;
 
 	drawer._updateViewport(m_pBuffer);