diff --git a/src/FrameBuffer.cpp b/src/FrameBuffer.cpp
index 56005315..ef7c25b9 100644
--- a/src/FrameBuffer.cpp
+++ b/src/FrameBuffer.cpp
@@ -196,11 +196,6 @@ u32 _cutHeight(u32 _address, u32 _height, u32 _stride)
 	return _height;
 }
 
-u32 cutHeight(u32 _address, u32 _height, u32 _stride)
-{
-	return _cutHeight(_address, _height, _stride);
-}
-
 void FrameBuffer::setBufferClearParams(u32 _fillcolor, s32 _ulx, s32 _uly, s32 _lrx, s32 _lry)
 {
 	m_cleared = true;
@@ -1273,3 +1268,16 @@ void FrameBuffer_AddAddress(u32 address, u32 _size)
 {
 	RDRAMtoColorBuffer::get().addAddress(address, _size);
 }
+
+u32 cutHeight(u32 _address, u32 _height, u32 _stride)
+{
+	return _cutHeight(_address, _height, _stride);
+}
+
+void calcCoordsScales(const FrameBuffer * _pBuffer, f32 & _scaleX, f32 & _scaleY)
+{
+	const u32 bufferWidth = _pBuffer != nullptr ? _pBuffer->m_width : VI.width;
+	const u32 bufferHeight = VI_GetMaxBufferHeight(bufferWidth);
+	_scaleX = 1.0f / f32(bufferWidth);
+	_scaleY = 1.0f / f32(bufferHeight);
+}
diff --git a/src/FrameBuffer.h b/src/FrameBuffer.h
index 2c2e432d..03889b06 100644
--- a/src/FrameBuffer.h
+++ b/src/FrameBuffer.h
@@ -125,6 +125,7 @@ FrameBufferList & frameBufferList()
 }
 
 u32 cutHeight(u32 _address, u32 _height, u32 _stride);
+void calcCoordsScales(const FrameBuffer * _pBuffer, f32 & _scaleX, f32 & _scaleY);
 
 void FrameBuffer_Init();
 void FrameBuffer_Destroy();
diff --git a/src/Graphics/OpenGLContext/GLSL/glsl_CombinerProgramUniformFactory.cpp b/src/Graphics/OpenGLContext/GLSL/glsl_CombinerProgramUniformFactory.cpp
index 8d348bed..d8bc96fa 100644
--- a/src/Graphics/OpenGLContext/GLSL/glsl_CombinerProgramUniformFactory.cpp
+++ b/src/Graphics/OpenGLContext/GLSL/glsl_CombinerProgramUniformFactory.cpp
@@ -588,9 +588,8 @@ public:
 
 	void update(bool _force) override
 	{
-		FrameBuffer * pCurrentBuffer = frameBufferList().getCurrent();
-		const float scaleX = pCurrentBuffer != nullptr ? 1.0f / pCurrentBuffer->m_width : VI.rwidth;
-		const float scaleY = pCurrentBuffer != nullptr ? 1.0f / pCurrentBuffer->m_height : VI.rheight;
+		f32 scaleX, scaleY;
+		calcCoordsScales(frameBufferList().getCurrent(), scaleX, scaleY);
 		uScreenCoordsScale.set(2.0f*scaleX, -2.0f*scaleY, _force);
 	}
 
diff --git a/src/GraphicsDrawer.cpp b/src/GraphicsDrawer.cpp
index 01d1249b..10ba9a4d 100644
--- a/src/GraphicsDrawer.cpp
+++ b/src/GraphicsDrawer.cpp
@@ -213,7 +213,6 @@ void GraphicsDrawer::_updateViewport() const
 		if (_needAdjustCoordinate(wnd))
 			Xf = _adjustViewportX(Xf);
 		const s32 X = (s32)(Xf * scaleX);
-//		const s32 Y = gSP.viewport.vscale[1] < 0 ? (s32)((gSP.viewport.y + gSP.viewport.vscale[1] * 2.0f) * scaleY) : (s32)((VI.height - (gSP.viewport.y + gSP.viewport.height)) * scaleY);
 		const s32 Y = (s32)(gSP.viewport.y * scaleY);
 		gfxContext.setViewport(X, Y,
 			std::max((s32)(gSP.viewport.width * scaleX), 0), std::max((s32)(gSP.viewport.height * scaleY), 0));
@@ -224,7 +223,6 @@ void GraphicsDrawer::_updateViewport() const
 		if (_needAdjustCoordinate(wnd))
 			Xf = _adjustViewportX(Xf);
 		const s32 X = (s32)(Xf * scaleX);
-//		const s32 Y = gSP.viewport.vscale[1] < 0 ? (s32)((gSP.viewport.y + gSP.viewport.vscale[1] * 2.0f) * scaleY) : (s32)((pCurrentBuffer->m_height - (gSP.viewport.y + gSP.viewport.height)) * scaleY);
 		const s32 Y = (s32)(gSP.viewport.y * scaleY);
 		gfxContext.setViewport(X, Y,
 			std::max((s32)(gSP.viewport.width * scaleX), 0), std::max((s32)(gSP.viewport.height * scaleY), 0));
@@ -236,10 +234,18 @@ void GraphicsDrawer::_updateScreenCoordsViewport() const
 {
 	DisplayWindow & wnd = DisplayWindow::get();
 	FrameBuffer * pCurrentBuffer = frameBufferList().getCurrent();
-	if (pCurrentBuffer == nullptr)
-		gfxContext.setViewport(0, 0, wnd.getScreenWidth(), wnd.getScreenHeight());
-	else
-		gfxContext.setViewport(0, 0, s32(pCurrentBuffer->m_width*pCurrentBuffer->m_scaleX), s32(pCurrentBuffer->m_height*pCurrentBuffer->m_scaleY));
+
+	u32 bufferWidth;
+	f32 viewportScale;
+	if (pCurrentBuffer == nullptr) {
+		bufferWidth = VI.width;
+		viewportScale = wnd.getScaleX();
+	} else {
+		bufferWidth = pCurrentBuffer->m_width;
+		viewportScale = pCurrentBuffer->m_scaleX;
+	}
+	const u32 bufferHeight = VI_GetMaxBufferHeight(bufferWidth);
+	gfxContext.setViewport(0, 0, (s32)(bufferWidth * viewportScale), (s32)(bufferHeight * viewportScale));
 	gSP.changed |= CHANGED_VIEWPORT;
 }
 
@@ -849,17 +855,12 @@ void GraphicsDrawer::drawRect(int _ulx, int _uly, int _lrx, int _lry)
 
 	m_drawingState = DrawingState::Rect;
 
-	FrameBuffer * pCurrentBuffer = frameBufferList().getCurrent();
-	DisplayWindow & wnd = dwnd();
-	if (pCurrentBuffer == nullptr)
-		gfxContext.setViewport(0, 0, wnd.getScreenWidth(), wnd.getScreenHeight());
-	else
-		gfxContext.setViewport(0, 0, pCurrentBuffer->m_width*pCurrentBuffer->m_scaleX, pCurrentBuffer->m_height*pCurrentBuffer->m_scaleY);
+	_updateScreenCoordsViewport();
 
 	gfxContext.enable(enable::CULL_FACE, false);
 
-	const float scaleX = pCurrentBuffer != nullptr ? 1.0f / pCurrentBuffer->m_width : VI.rwidth;
-	const float scaleY = pCurrentBuffer != nullptr ? 1.0f / pCurrentBuffer->m_height : VI.rheight;
+	f32 scaleX, scaleY;
+	calcCoordsScales(frameBufferList().getCurrent(), scaleX, scaleY);
 	const float Z = (gDP.otherMode.depthSource == G_ZS_PRIM) ? gDP.primDepth.z : 0.0f;
 	const float W = 1.0f;
 	m_rect[0].x = (float)_ulx * (2.0f * scaleX) - 1.0;
@@ -879,6 +880,7 @@ void GraphicsDrawer::drawRect(int _ulx, int _uly, int _lrx, int _lry)
 	m_rect[3].z = Z;
 	m_rect[3].w = W;
 
+	DisplayWindow & wnd = dwnd();
 	if (wnd.isAdjustScreen() && (gDP.colorImage.width > VI.width * 98 / 100) && (_lrx - _ulx < VI.width * 9 / 10)) {
 		const float scale = wnd.getAdjustScale();
 		for (u32 i = 0; i < 4; ++i)
@@ -1092,8 +1094,8 @@ void GraphicsDrawer::drawTexturedRect(const TexturedRectParams & _params)
 		&& ((cache.current[0]->frameBufferTexture == CachedTexture::fbNone && !cache.current[0]->bHDTexture))
 		&& (cache.current[1] == nullptr || (cache.current[1]->frameBufferTexture == CachedTexture::fbNone && !cache.current[1]->bHDTexture));
 
-	const float scaleX = pCurrentBuffer != nullptr ? 1.0f / pCurrentBuffer->m_width : VI.rwidth;
-	const float scaleY = pCurrentBuffer != nullptr ? 1.0f / pCurrentBuffer->m_height : VI.rheight;
+	f32 scaleX, scaleY;
+	calcCoordsScales(pCurrentBuffer, scaleX, scaleY);
 	const float Z = (gDP.otherMode.depthSource == G_ZS_PRIM) ? gDP.primDepth.z : 0.0f;
 	const float W = 1.0f;
 	f32 uly, lry;
@@ -1241,10 +1243,7 @@ void GraphicsDrawer::drawTexturedRect(const TexturedRectParams & _params)
 	if (bUseTexrectDrawer)
 		m_texrectDrawer.add();
 	else {
-		if (pCurrentBuffer == nullptr)
-			gfxContext.setViewport(0, 0, wnd.getScreenWidth(), wnd.getScreenHeight());
-		else
-			gfxContext.setViewport(0, 0, pCurrentBuffer->m_width*pCurrentBuffer->m_scaleX, pCurrentBuffer->m_height*pCurrentBuffer->m_scaleY);
+		_updateScreenCoordsViewport();
 
 		Context::DrawRectParameters rectParams;
 		rectParams.mode = drawmode::TRIANGLE_STRIP;
diff --git a/src/TexrectDrawer.cpp b/src/TexrectDrawer.cpp
index 107d8b83..66c5e43c 100644
--- a/src/TexrectDrawer.cpp
+++ b/src/TexrectDrawer.cpp
@@ -97,6 +97,12 @@ void TexrectDrawer::destroy()
 	m_programClear.reset();
 }
 
+void TexrectDrawer::_setViewport() const
+{
+	const u32 bufferWidth = m_pBuffer == nullptr ? VI.width : m_pBuffer->m_width;
+	gfxContext.setViewport(0, 0, bufferWidth, VI_GetMaxBufferHeight(bufferWidth));
+}
+
 void TexrectDrawer::add()
 {
 	DisplayWindow & wnd = dwnd();
@@ -150,10 +156,7 @@ void TexrectDrawer::add()
 		gfxContext.enable(enable::DEPTH_TEST, false);
 		gfxContext.enable(enable::BLEND, false);
 
-		if (m_pBuffer == nullptr)
-			gfxContext.setViewport(0, 0, VI.width, VI.height);
-		else
-			gfxContext.setViewport(0, 0, m_pBuffer->m_width, m_pBuffer->m_height);
+		_setViewport();
 
 		gfxContext.setScissor((s32)gDP.scissor.ulx, (s32)gDP.scissor.uly, (s32)(gDP.scissor.lrx - gDP.scissor.ulx), (s32)(gDP.scissor.lry - gDP.scissor.uly));
 
@@ -227,8 +230,10 @@ bool TexrectDrawer::draw()
 
 	RectVertex * rect = drawer.m_rect;
 
-	const float scaleX = (m_pBuffer != nullptr ? 1.0f / m_pBuffer->m_width : VI.rwidth) * 2.0f;
-	const float scaleY = (m_pBuffer != nullptr ? 1.0f / m_pBuffer->m_height : VI.rheight) * 2.0f;
+	f32 scaleX, scaleY;
+	calcCoordsScales(m_pBuffer, scaleX, scaleY);
+	scaleX *= 2.0f;
+	scaleY *= 2.0f;
 
 	const float s0 = (m_ulx + 1.0f) / scaleX / (float)m_pTexture->realWidth;
 	const float t1 = (m_uly + 1.0f) / scaleY / (float)m_pTexture->realHeight;
@@ -236,10 +241,7 @@ bool TexrectDrawer::draw()
 	const float t0 = (m_lry + 1.0f) / scaleY / (float)m_pTexture->realHeight;
 	const float W = 1.0f;
 
-	if (m_pBuffer == nullptr)
-		gfxContext.setViewport(0, wnd.getHeightOffset(), wnd.getScreenWidth(), wnd.getScreenHeight());
-	else
-		gfxContext.setViewport(0, 0, m_pBuffer->m_width*m_pBuffer->m_scaleX, m_pBuffer->m_height*m_pBuffer->m_scaleY);
+	drawer._updateScreenCoordsViewport();
 
 	textureCache().activateTexture(0, m_pTexture);
 	// Disable filtering to avoid black outlines
@@ -299,10 +301,7 @@ bool TexrectDrawer::draw()
 	rect[2].y = -m_lry;
 	rect[3].y = -m_lry;
 
-	if (m_pBuffer == nullptr)
-		gfxContext.setViewport(0, 0, VI.width, VI.height);
-	else
-		gfxContext.setViewport(0, 0, m_pBuffer->m_width, m_pBuffer->m_height);
+	_setViewport();
 
 	gfxContext.enable(enable::BLEND, false);
 	gfxContext.enable(enable::SCISSOR_TEST, false);
diff --git a/src/TexrectDrawer.h b/src/TexrectDrawer.h
index 0dbc9c9c..810cef66 100644
--- a/src/TexrectDrawer.h
+++ b/src/TexrectDrawer.h
@@ -21,6 +21,8 @@ public:
 	bool draw();
 	bool isEmpty();
 private:
+	void _setViewport() const;
+
 	u32 m_numRects;
 	u64 m_otherMode;
 	u64 m_mux;