gsdx: new anti-glitches upscaling hack: UserHacks_round_sprite_offset

It is replacement of the previous hack (UserHacks_stretch_sprite). Don't enable both in the same time!

The idea of the hack is to move the sprite to the pixel boundary. It
avoids most of rounding issue. It also rescales verticaly the sprite (avoid horizontal line on ace combat).
I don't like this rescaling maybe we can limit it to only 1 pixels.

On my limited testcase, results are much better with any upscaling factor.

I still have a bad line in Kingdom heart. If you have issue with others
game please provide us a GS dump.

plugins/GSdx/GSRendererDX.cpp

@@ -288,7 +288,7 @@ void GSRendererDX::DrawPrims(GSTexture* rt, GSTexture* ds, GSTextureCache::Sourc
 		bool bilinear = m_filter == 2 ? m_vt.IsLinear() : m_filter != 0;
 		bool simple_sample = !tex->m_palette && cpsm.fmt == 0 && context->CLAMP.WMS < 3 && context->CLAMP.WMT < 3;
 		// Don't force extra filtering on sprite (it creates various upscaling issue)
-		bilinear &= !((m_vt.m_primclass == GS_SPRITE_CLASS) && m_userhacks_stretch_sprite && !m_vt.IsLinear());
+		bilinear &= !((m_vt.m_primclass == GS_SPRITE_CLASS) && (m_userhacks_stretch_sprite || m_userhacks_round_sprite_offset) && !m_vt.IsLinear());
 
 		ps_sel.wms = context->CLAMP.WMS;
 		ps_sel.wmt = context->CLAMP.WMT;

plugins/GSdx/GSRendererHW.cpp

@@ -34,6 +34,7 @@ GSRendererHW::GSRendererHW(GSTextureCache* tc)
 	m_userhacks_skipdraw = !!theApp.GetConfig("UserHacks", 0) ? theApp.GetConfig("UserHacks_SkipDraw", 0) : 0;
 	m_userhacks_align_sprite_X = !!theApp.GetConfig("UserHacks_align_sprite_X", 0) && !!theApp.GetConfig("UserHacks", 0);
 	m_userhacks_stretch_sprite = !!theApp.GetConfig("UserHacks_stretch_sprite", 0) && !!theApp.GetConfig("UserHacks", 0);
+	m_userhacks_round_sprite_offset = !!theApp.GetConfig("UserHacks_round_sprite_offset", 0) && !!theApp.GetConfig("UserHacks", 0);
 
 	if(!m_nativeres)
 	{
@@ -322,12 +323,15 @@ void GSRendererHW::Draw()
 	context->FRAME.FBMSK = fm;
 	context->ZBUF.ZMSK = zm != 0;
 
-	if ((m_upscale_multiplier > 1) && (m_vt.m_primclass == GS_SPRITE_CLASS)) {
+	// A couple of hack to avoid upscaling issue. So far it seems to impacts only sprite without linear filtering
+	if ((m_upscale_multiplier > 1) && (m_vt.m_primclass == GS_SPRITE_CLASS) /*&& !m_vt.IsLinear()*/) {
+		// TODO: It could be a good idea to check context->CLAMP.WMS/WMT values on the following hack
+
+		size_t count = m_vertex.next;
+		GSVertex* v = &m_vertex.buff[0];
+
 		// Hack to avoid vertical black line in various games (ace combat/tekken)
 		if (m_userhacks_align_sprite_X) {
-			size_t count = m_vertex.next;
-			GSVertex* v = &m_vertex.buff[0];
-
 			// Note for performance reason I do the check only once on the first
 			// primitive
 			int win_position = v[1].XYZ.X - context->XYOFFSET.OFX;
@@ -347,9 +351,7 @@ void GSRendererHW::Draw()
 		}
 
 		// Hack to avoid black line in various 2D games.
-		if (m_userhacks_stretch_sprite) {
+		if (m_userhacks_stretch_sprite && !m_vt.IsLinear()) {
-			size_t count = m_vertex.next;
-			GSVertex* v = &m_vertex.buff[0];
 			for(size_t i = 0; i < count; i += 2) {
 				if (v[i+1].U < v[i].U)
 					v[i+1].U += m_sub_texel_offset;
@@ -362,6 +364,45 @@ void GSRendererHW::Draw()
 					v[i+1].V -= m_sub_texel_offset;
 			}
 		}
+
+		if (m_userhacks_round_sprite_offset && !m_vt.IsLinear()) {
+			for(size_t i = 0; i < count; i += 2) {
+				// 2nd vertex is always on the right so I'm sure it is bigger than the context
+				int pixel_offset_X = (v[i+1].XYZ.X - context->XYOFFSET.OFX) & 0xF;
+				int pixel_offset_Y = (v[i+1].XYZ.Y - context->XYOFFSET.OFY) & 0xF;
+				int length_Y = v[i+1].XYZ.Y - v[i].XYZ.Y;
+
+				// Bonus to avoid rounding issue
+				if (v[i+1].U < v[i].U)
+					pixel_offset_X += 16 - 1;
+				else
+					pixel_offset_X += 1;
+
+				// TODO check negative case
+				if (v[i+1].V < v[i].V)
+					pixel_offset_Y += 16 - 1;
+				else
+					pixel_offset_Y += 1;
+
+				// Tranlate the primitive to the pixel boundary
+				v[i].U   &= ~0xF;
+				v[i].U   += pixel_offset_X;
+				v[i+1].U &= ~0xF;
+				v[i+1].U += pixel_offset_X;
+
+				v[i].V   &= ~0xF;
+				v[i].V   += pixel_offset_Y;
+				// I'm not confident with the negative case
+				if (v[i+1].V < v[i].V) {
+					v[i+1].V  = v[i].V - length_Y;
+				} else {
+					v[i+1].V  = v[i].V + length_Y;
+				}
+
+				//v[i+1].V &= ~0xF;
+				//v[i+1].V += pixel_offset_Y;
+			}
+		}
 	}
 
 	//

plugins/GSdx/GSRendererHW.h

@@ -138,6 +138,7 @@ protected:
 	virtual void DrawPrims(GSTexture* rt, GSTexture* ds, GSTextureCache::Source* tex) = 0;
 
 	bool m_userhacks_stretch_sprite;
+	bool m_userhacks_round_sprite_offset;
 
 public:
 	GSRendererHW(GSTextureCache* tc);

plugins/GSdx/GSRendererOGL.cpp

@@ -415,7 +415,7 @@ void GSRendererOGL::DrawPrims(GSTexture* rt, GSTexture* ds, GSTextureCache::Sour
 		bool bilinear = m_filter == 2 ? m_vt.IsLinear() : m_filter != 0;
 		bool simple_sample = !tex->m_palette && cpsm.fmt == 0 && context->CLAMP.WMS < 3 && context->CLAMP.WMT < 3;
 		// Don't force extra filtering on sprite (it creates various upscaling issue)
-		bilinear &= !((m_vt.m_primclass == GS_SPRITE_CLASS) && m_userhacks_stretch_sprite && !m_vt.IsLinear());
+		bilinear &= !((m_vt.m_primclass == GS_SPRITE_CLASS) && (m_userhacks_stretch_sprite || m_userhacks_round_sprite_offset) && !m_vt.IsLinear());
 
 		ps_sel.wms = context->CLAMP.WMS;
 		ps_sel.wmt = context->CLAMP.WMT;