GPU/HW: Fix MSAA+depth buffer combination

Clear should wipe out all samples, copy should copy all samples.

src/core/gpu_hw.cpp

@@ -1687,21 +1687,19 @@ bool GPU_HW::CompilePipelines(Error* error)
       return false;
   }
 
-  plconfig.SetTargetFormats(VRAM_RT_FORMAT);
-  plconfig.render_pass_flags = GPUPipeline::NoRenderPassFlags;
-  plconfig.depth = GPUPipeline::DepthState::GetNoTestsState();
-  plconfig.blend = GPUPipeline::BlendState::GetNoBlendingState();
-  plconfig.samples = 1;
-  plconfig.per_sample_shading = false;
-
   if (m_pgxp_depth_buffer)
   {
-    std::unique_ptr<GPUShader> fs = g_gpu_device->CreateShader(GPUShaderStage::Fragment, shadergen.GetLanguage(),
-                                                               shadergen.GenerateCopyFragmentShader(), error);
+    std::unique_ptr<GPUShader> fs = g_gpu_device->CreateShader(
+      GPUShaderStage::Fragment, shadergen.GetLanguage(), shadergen.GenerateVRAMCopyDepthFragmentShader(msaa), error);
     if (!fs)
       return false;
 
     plconfig.fragment_shader = fs.get();
+    plconfig.render_pass_flags = GPUPipeline::NoRenderPassFlags;
+    plconfig.depth = GPUPipeline::DepthState::GetNoTestsState();
+    plconfig.blend = GPUPipeline::BlendState::GetNoBlendingState();
+    plconfig.samples = m_multisamples;
+    plconfig.per_sample_shading = true;
     plconfig.SetTargetFormats(VRAM_DS_COLOR_FORMAT);
     if (!(m_copy_depth_pipeline = g_gpu_device->CreatePipeline(plconfig, error)))
       return false;
@@ -1714,6 +1712,7 @@ bool GPU_HW::CompilePipelines(Error* error)
     SetScreenQuadInputLayout(plconfig);
     plconfig.vertex_shader = m_screen_quad_vertex_shader.get();
     plconfig.fragment_shader = fs.get();
+    plconfig.per_sample_shading = false;
     if (!m_use_rov_for_shader_blend)
     {
       plconfig.SetTargetFormats(VRAM_RT_FORMAT, depth_buffer_format);

src/core/gpu_hw_shadergen.cpp

@@ -1917,6 +1917,27 @@ std::string GPU_HW_ShaderGen::GenerateVRAMUpdateDepthFragmentShader(bool msaa) c
   return std::move(ss).str();
 }
 
+std::string GPU_HW_ShaderGen::GenerateVRAMCopyDepthFragmentShader(bool msaa) const
+{
+  std::stringstream ss;
+  WriteHeader(ss);
+  DefineMacro(ss, "MULTISAMPLED", msaa);
+  DeclareTexture(ss, "samp0", 0, msaa);
+  DeclareFragmentEntryPoint(ss, 0, 1, {}, msaa, 1, false, false, msaa, msaa, msaa);
+
+  ss << R"(
+{
+#if MULTISAMPLED
+  o_col0 = float4(LOAD_TEXTURE_MS(samp0, int2(v_pos.xy), int(f_sample_index)).r, 0.0, 0.0, 0.0);
+#else
+  o_col0 = float4(SAMPLE_TEXTURE(samp0, v_tex0).r, 0.0, 0.0, 0.0);
+#endif
+}
+)";
+
+  return std::move(ss).str();
+}
+
 std::string GPU_HW_ShaderGen::GenerateVRAMClearDepthFragmentShader(bool write_depth_as_rt) const
 {
   std::stringstream ss;

src/core/gpu_hw_shadergen.h

@@ -35,6 +35,7 @@ public:
   std::string GenerateVRAMFillFragmentShader(bool wrapped, bool interlaced, bool write_mask_as_depth,
                                              bool write_depth_as_rt) const;
   std::string GenerateVRAMUpdateDepthFragmentShader(bool msaa) const;
+  std::string GenerateVRAMCopyDepthFragmentShader(bool msaa) const;
   std::string GenerateVRAMClearDepthFragmentShader(bool write_depth_as_rt) const;
   std::string GenerateVRAMExtractFragmentShader(u32 resolution_scale, u32 multisamples, bool color_24bit,
                                                 bool depth_buffer) const;