gsdx-d3d11: Extend sw blending to BLEND_NO_BAR which is also free and doesn't require rt sample nor any barriers.

It helps light rendering in SW Battlefront 2, VP2 also triggers it but needs to be further tested what it does.

plugins/GSdx/Renderers/DX11/GSRendererDX11.cpp

@@ -529,6 +529,10 @@ void GSRendererDX11::EmulateBlending()
 	uint8 blend_index  = uint8(((ALPHA.A * 3 + ALPHA.B) * 3 + ALPHA.C) * 3 + ALPHA.D);
 	int blend_flag = m_dev->GetBlendFlags(blend_index);
 
+	// SW free blend.
+	bool free_blend = !!(blend_flag & (BLEND_NO_BAR|BLEND_ACCU));
+
+	// Do the multiplication in shader for blending accumulation: Cs*As + Cd or Cs*Af + Cd
 	bool accumulation_blend = !!(blend_flag & BLEND_ACCU);
 
 	switch (m_sw_blending)
@@ -536,7 +540,7 @@ void GSRendererDX11::EmulateBlending()
 		case ACC_BLEND_HIGH_D3D11:
 		case ACC_BLEND_MEDIUM_D3D11:
 		case ACC_BLEND_BASIC_D3D11:
-			sw_blending |= accumulation_blend;
+			sw_blending |= free_blend;
 			// fall through
 		default: break;
 	}
@@ -549,6 +553,9 @@ void GSRendererDX11::EmulateBlending()
 		m_ps_sel.hdr = 1;
 	}
 
+	/*fprintf(stderr, "%d: BLEND_INFO: %d/%d/%d/%d. Clamp:%d. Prim:%d number %d (sw %d)\n",
+		s_n, ALPHA.A, ALPHA.B, ALPHA.C, ALPHA.D, m_env.COLCLAMP.CLAMP, m_vt.m_primclass, m_vertex.next, sw_blending);*/
+
 	if (sw_blending)
 	{
 		m_ps_sel.blend_a = ALPHA.A;
@@ -572,8 +579,9 @@ void GSRendererDX11::EmulateBlending()
 		}
 		else
 		{
-			// We shouldn't hit this path as currently only accumulation blend is implemented
-			ASSERT(0);
+			// Disable HW blending
+			// Only BLEND_NO_BAR should hit this code path for now.
+			m_om_bsel.abe = 0;
 		}
 
 		// Require the fix alpha vlaue