GPU/HW: Set alpha to mask bit setting

src/core/gpu_hw.cpp

@@ -310,6 +310,15 @@ void GPU_HW::DispatchRenderCommand(RenderCommand rc, u32 num_vertices, const u32
     m_batch_ubo_dirty = true;
   }
 
+  if (m_batch.check_mask_before_draw != m_GPUSTAT.check_mask_before_draw ||
+      m_batch.set_mask_while_drawing != m_GPUSTAT.set_mask_while_drawing)
+  {
+    m_batch.check_mask_before_draw = m_GPUSTAT.check_mask_before_draw;
+    m_batch.set_mask_while_drawing = m_GPUSTAT.set_mask_while_drawing;
+    m_batch_ubo_data.u_set_mask_while_drawing = BoolToUInt32(m_GPUSTAT.set_mask_while_drawing);
+    m_batch_ubo_dirty = true;
+  }
+
   if (m_drawing_offset_changed)
   {
     m_drawing_offset_changed = false;

src/core/gpu_hw.h

@@ -71,6 +71,8 @@ protected:
     TextureMode texture_mode;
     TransparencyMode transparency_mode;
     bool dithering;
+    bool set_mask_while_drawing;
+    bool check_mask_before_draw;
 
     // We need two-pass rendering when using BG-FG blending and texturing, as the transparency can be enabled
     // on a per-pixel basis, and the opaque pixels shouldn't be blended at all.
@@ -95,6 +97,8 @@ protected:
     u32 u_texture_window_offset[2];
     float u_src_alpha_factor;
     float u_dst_alpha_factor;
+    u32 u_set_mask_while_drawing;
+    u32 padding[3];
   };
 
   struct RendererStats

src/core/gpu_hw_shadergen.cpp

@@ -292,7 +292,7 @@ void GPU_HW_ShaderGen::DeclareFragmentEntryPoint(std::stringstream& ss, u32 num_
 void GPU_HW_ShaderGen::WriteBatchUniformBuffer(std::stringstream& ss)
 {
   DeclareUniformBuffer(ss, {"int2 u_pos_offset", "uint2 u_texture_window_mask", "uint2 u_texture_window_offset",
-                            "float u_src_alpha_factor", "float u_dst_alpha_factor"});
+                            "float u_src_alpha_factor", "float u_dst_alpha_factor", "bool u_set_mask_while_drawing"});
 }
 
 std::string GPU_HW_ShaderGen::GenerateBatchVertexShader(bool textured)
@@ -505,7 +505,7 @@ int4 SampleFromVRAM(int4 texpage, float2 coord)
   #endif
 
   // Compute output alpha (mask bit)
-  float output_alpha = float(semitransparent);
+  float output_alpha = float(u_set_mask_while_drawing ? 1 : int(semitransparent));
 
   // Normalize
   float3 color = float3(icolor) / float3(255.0, 255.0, 255.0);