From 3df1670809c3b4dc1a36a728e4a3ce32b2d4182f Mon Sep 17 00:00:00 2001
From: Connor McLaughlin <stenzek@gmail.com>
Date: Tue, 4 Aug 2020 02:08:54 +1000
Subject: [PATCH] libretro: Try for a GLES context first depending on preferred
 renderer

---
 .../libretro_host_interface.cpp               |  9 +++--
 .../libretro_opengl_host_display.cpp          | 36 +++++++++++++++----
 .../libretro_opengl_host_display.h            |  2 +-
 3 files changed, 37 insertions(+), 10 deletions(-)

diff --git a/src/duckstation-libretro/libretro_host_interface.cpp b/src/duckstation-libretro/libretro_host_interface.cpp
index d60664d20..033a7658b 100644
--- a/src/duckstation-libretro/libretro_host_interface.cpp
+++ b/src/duckstation-libretro/libretro_host_interface.cpp
@@ -824,8 +824,13 @@ bool LibretroHostInterface::RequestHardwareRendererContext()
       break;
 
     case GPURenderer::HardwareOpenGL:
-      m_hw_render_callback_valid = LibretroOpenGLHostDisplay::RequestHardwareRendererContext(&m_hw_render_callback);
-      break;
+    {
+      const bool prefer_gles =
+        (preferred_renderer == RETRO_HW_CONTEXT_OPENGLES2 || preferred_renderer == RETRO_HW_CONTEXT_OPENGLES_VERSION);
+      m_hw_render_callback_valid =
+        LibretroOpenGLHostDisplay::RequestHardwareRendererContext(&m_hw_render_callback, prefer_gles);
+    }
+    break;
 
     default:
       Log_ErrorPrintf("Unhandled renderer %s", Settings::GetRendererName(renderer));
diff --git a/src/duckstation-libretro/libretro_opengl_host_display.cpp b/src/duckstation-libretro/libretro_opengl_host_display.cpp
index 97b9565ba..f508bcc19 100644
--- a/src/duckstation-libretro/libretro_opengl_host_display.cpp
+++ b/src/duckstation-libretro/libretro_opengl_host_display.cpp
@@ -23,15 +23,10 @@ void LibretroOpenGLHostDisplay::SetVSync(bool enabled)
   Log_DevPrintf("Ignoring SetVSync(%u)", BoolToUInt32(enabled));
 }
 
-bool LibretroOpenGLHostDisplay::RequestHardwareRendererContext(retro_hw_render_callback* cb)
+static bool TryDesktopVersions(retro_hw_render_callback* cb)
 {
-  // Prefer a desktop OpenGL context where possible. If we can't get this, try OpenGL ES.
   static constexpr std::array<std::tuple<u32, u32>, 11> desktop_versions_to_try = {
-    {/*{4, 6}, {4, 5}, {4, 4}, {4, 3}, {4, 2}, {4, 1}, {4, 0}, {3, 3}, {3, 2}, */ {3, 1}, {3, 0}}};
-  static constexpr std::array<std::tuple<u32, u32>, 4> es_versions_to_try = {{{3, 2}, {3, 1}, {3, 0}}};
-
-  cb->cache_context = true;
-  cb->bottom_left_origin = true;
+    {/*{4, 6}, {4, 5}, {4, 4}, {4, 3}, {4, 2}, {4, 1}, {4, 0}, */ {3, 3}, {3, 2}, {3, 1}, {3, 0}}};
 
   for (const auto& [major, minor] : desktop_versions_to_try)
   {
@@ -52,6 +47,13 @@ bool LibretroOpenGLHostDisplay::RequestHardwareRendererContext(retro_hw_render_c
       return true;
   }
 
+  return false;
+}
+
+static bool TryESVersions(retro_hw_render_callback* cb)
+{
+  static constexpr std::array<std::tuple<u32, u32>, 4> es_versions_to_try = {{{3, 2}, {3, 1}, {3, 0}}};
+
   for (const auto& [major, minor] : es_versions_to_try)
   {
     if (major >= 3 && minor > 0)
@@ -71,6 +73,26 @@ bool LibretroOpenGLHostDisplay::RequestHardwareRendererContext(retro_hw_render_c
       return true;
   }
 
+  return false;
+}
+
+bool LibretroOpenGLHostDisplay::RequestHardwareRendererContext(retro_hw_render_callback* cb, bool prefer_gles)
+{
+  // Prefer a desktop OpenGL context where possible. If we can't get this, try OpenGL ES.
+  cb->cache_context = true;
+  cb->bottom_left_origin = true;
+
+  if (!prefer_gles)
+  {
+    if (TryDesktopVersions(cb) || TryESVersions(cb))
+      return true;
+  }
+  else
+  {
+    if (TryESVersions(cb) || TryDesktopVersions(cb))
+      return true;
+  }
+
   Log_ErrorPrint("Failed to set any GL HW renderer");
   return false;
 }
diff --git a/src/duckstation-libretro/libretro_opengl_host_display.h b/src/duckstation-libretro/libretro_opengl_host_display.h
index 173d4c522..2f5bb2012 100644
--- a/src/duckstation-libretro/libretro_opengl_host_display.h
+++ b/src/duckstation-libretro/libretro_opengl_host_display.h
@@ -13,7 +13,7 @@ public:
   LibretroOpenGLHostDisplay();
   ~LibretroOpenGLHostDisplay();
 
-  static bool RequestHardwareRendererContext(retro_hw_render_callback* cb);
+  static bool RequestHardwareRendererContext(retro_hw_render_callback* cb, bool prefer_gles);
 
   RenderAPI GetRenderAPI() const override;