From d468814a6d981a5c00290fe7316c4490edefad12 Mon Sep 17 00:00:00 2001
From: Connor McLaughlin <stenzek@gmail.com>
Date: Tue, 10 Nov 2020 20:55:35 +1000
Subject: [PATCH] GPU: Disable texture filters when dual-source blend is
 unsupported

---
 src/core/gpu_hw.cpp | 13 ++++++++++++-
 src/core/gpu_hw.h   |  7 +++++++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/src/core/gpu_hw.cpp b/src/core/gpu_hw.cpp
index 0e6c152d1..5996a0fa5 100644
--- a/src/core/gpu_hw.cpp
+++ b/src/core/gpu_hw.cpp
@@ -55,7 +55,6 @@ bool GPU_HW::Initialize(HostDisplay* host_display)
   m_texture_filtering = g_settings.gpu_texture_filter;
   m_using_uv_limits = ShouldUseUVLimits();
   m_chroma_smoothing = g_settings.gpu_24bit_chroma_smoothing;
-  PrintSettingsToLog();
 
   if (m_multisamples != g_settings.gpu_multisamples)
   {
@@ -68,7 +67,15 @@ bool GPU_HW::Initialize(HostDisplay* host_display)
     g_host_interface->AddOSDMessage(
       g_host_interface->TranslateStdString("OSDMessage", "SSAA is not supported, using MSAA instead."), 20.0f);
   }
+  if (!m_supports_dual_source_blend && TextureFilterRequiresDualSourceBlend(m_texture_filtering))
+  {
+    g_host_interface->AddFormattedOSDMessage(
+      20.0f, g_host_interface->TranslateString("OSDMessage", "Texture filter '%s' is not supported on your device."),
+      Settings::GetTextureFilterDisplayName(m_texture_filtering));
+    m_texture_filtering = GPUTextureFilter::Nearest;
+  }
 
+  PrintSettingsToLog();
   return true;
 }
 
@@ -150,6 +157,10 @@ void GPU_HW::UpdateHWSettings(bool* framebuffer_changed, bool* shaders_changed)
   m_texture_filtering = g_settings.gpu_texture_filter;
   m_using_uv_limits = use_uv_limits;
   m_chroma_smoothing = g_settings.gpu_24bit_chroma_smoothing;
+
+  if (!m_supports_dual_source_blend && TextureFilterRequiresDualSourceBlend(m_texture_filtering))
+    m_texture_filtering = GPUTextureFilter::Nearest;
+
   PrintSettingsToLog();
 }
 
diff --git a/src/core/gpu_hw.h b/src/core/gpu_hw.h
index 10d2694f6..31c16a2be 100644
--- a/src/core/gpu_hw.h
+++ b/src/core/gpu_hw.h
@@ -225,6 +225,13 @@ protected:
     }
   }
 
+  /// Returns true if the specified texture filtering mode requires dual-source blending.
+  ALWAYS_INLINE bool TextureFilterRequiresDualSourceBlend(GPUTextureFilter filter)
+  {
+    return (filter == GPUTextureFilter::Bilinear || filter == GPUTextureFilter::JINC2 ||
+            filter == GPUTextureFilter::xBR);
+  }
+
   /// Returns true if alpha blending should be enabled for drawing the current batch.
   ALWAYS_INLINE bool UseAlphaBlending(TransparencyMode transparency_mode, BatchRenderMode render_mode) const
   {