GS/HW: Detect clears spanning multiple sprites

Fixes GT4 rendering to >1000x1000 targets.

pcsx2/GS/Renderers/HW/GSRendererHW.cpp

@@ -1667,6 +1667,8 @@ void GSRendererHW::Draw()
 
 			if (is_zero_clear && OI_GsMemClear() && clear_height_valid)
 			{
+				GL_INS("Clear draw with mem clear and valid clear height, invalidating.");
+
 				g_texture_cache->InvalidateVideoMem(context->offset.fb, m_r, false, true);
 				g_texture_cache->InvalidateVideoMemType(GSTextureCache::RenderTarget, m_cached_ctx.FRAME.Block());
 
@@ -1835,8 +1837,7 @@ void GSRendererHW::Draw()
 		// Normally we would use 1024 here to match the clear above, but The Godfather does a 1023x1023 draw instead
 		// (very close to 1024x1024, but apparently the GS rounds down..). So, catch that here, we don't want to
 		// create that target, because the clear isn't black, it'll hang around and never get invalidated.
-		const bool is_square = (t_size.y == t_size.x) && m_r.w >= 1023 && 
-			((m_index.tail == 2 && m_vt.m_primclass == GS_SPRITE_CLASS) || (m_index.tail == 6 && m_vt.m_primclass == GS_TRIANGLE_CLASS));
+		const bool is_square = (t_size.y == t_size.x) && m_r.w >= 1023 && PrimitiveCoversWithoutGaps();
 		const bool is_clear = is_possible_mem_clear && is_square;
 		rt = g_texture_cache->LookupTarget(FRAME_TEX0, t_size, target_scale, GSTextureCache::RenderTarget, true,
 			fm, false, is_clear, force_preload);
@@ -1844,6 +1845,7 @@ void GSRendererHW::Draw()
 		// Draw skipped because it was a clear and there was no target.
 		if (!rt)
 		{
+			GL_INS("Clear draw with no target, skipping.");
 			cleanup_cancelled_draw();
 			OI_GsMemClear();
 			return;
@@ -5055,7 +5057,7 @@ bool GSRendererHW::OI_GsMemClear()
 							&& (m_cached_ctx.FRAME.PSM & 0xF) == (m_cached_ctx.ZBUF.PSM & 0xF) && m_vt.m_eq.z == 1 && m_vertex.buff[1].XYZ.Z == m_vertex.buff[1].RGBAQ.U32[0];
 
 	// Limit it further to a full screen 0 write
-	if (((m_vertex.next == 2) || ZisFrame) && m_vt.m_eq.rgba == 0xFFFF)
+	if ((PrimitiveCoversWithoutGaps() || ZisFrame) && m_vt.m_eq.rgba == 0xFFFF)
 	{
 		const GSOffset& off = m_context->offset.fb;
 		GSVector4i r = GSVector4i(m_vt.m_min.p.upld(m_vt.m_max.p)).rintersect(GSVector4i(m_context->scissor.in));
@@ -5194,6 +5196,35 @@ bool GSRendererHW::IsBlendedOrOpaque()
 	return (!PRIM->ABE || IsOpaque() || m_context->ALPHA.IsCdOutput());
 }
 
+bool GSRendererHW::PrimitiveCoversWithoutGaps() const
+{
+	// Draw shouldn't be offset.
+	if ((m_r.eq32(GSVector4i::zero())).mask() & 0xff00)
+		return false;
+
+	// This is potentially wrong for fans/strips...
+	if (m_vt.m_primclass == GS_TRIANGLE_CLASS)
+		return (m_index.tail == 6);
+	else if (m_vt.m_primclass != GS_SPRITE_CLASS)
+		return false;
+
+	// Simple case: one sprite.
+	if (m_index.tail == 2)
+		return true;
+
+	// Borrowed from MergeSprite().
+	const GSVertex* v = &m_vertex.buff[0];
+	const int first_dpX = v[1].XYZ.X - v[0].XYZ.X;
+	for (u32 i = 0; i < m_vertex.next; i += 2)
+	{
+		const int dpX = v[i + 1].XYZ.X - v[i].XYZ.X;
+		if (dpX != first_dpX)
+			return false;
+	}
+
+	return true;
+}
+
 bool GSRendererHW::IsConstantDirectWriteMemClear()
 {
 	const bool direct_draw = (m_vt.m_primclass == GS_SPRITE_CLASS) || (m_index.tail == 6 && m_vt.m_primclass == GS_TRIANGLE_CLASS);

pcsx2/GS/Renderers/HW/GSRendererHW.h

@@ -54,6 +54,7 @@ private:
 	bool CanUseSwSpriteRender();
 	bool IsConstantDirectWriteMemClear();
 	bool IsBlendedOrOpaque();
+	bool PrimitiveCoversWithoutGaps() const;
 
 	enum class CLUTDrawTestResult
 	{