From 6e2223b517acb6bd4c97c9fcd9dcba91d4a2e917 Mon Sep 17 00:00:00 2001
From: Stenzek <stenzek@gmail.com>
Date: Sun, 15 Dec 2024 22:04:54 +1000
Subject: [PATCH] OpenGLDevice: Fix surfaceless context switch

---
 src/core/host.cpp               | 6 ++++++
 src/util/gpu_device.cpp         | 9 +++++++--
 src/util/gpu_device.h           | 1 +
 src/util/opengl_context_egl.cpp | 6 ++++--
 src/util/opengl_device.cpp      | 6 ++++++
 src/util/opengl_device.h        | 1 +
 6 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/src/core/host.cpp b/src/core/host.cpp
index 6083c6ee1..cc5da139f 100644
--- a/src/core/host.cpp
+++ b/src/core/host.cpp
@@ -459,7 +459,13 @@ void Host::UpdateDisplayWindow(bool fullscreen)
 
   // if surfaceless, just leave it
   if (wi->IsSurfaceless())
+  {
+    DEV_LOG("Switching to surfaceless device");
+    if (!g_gpu_device->SwitchToSurfacelessRendering(&error))
+      ERROR_LOG("Failed to switch to surfaceless, rendering commands may fail: {}", error.GetDescription());
+
     return;
+  }
 
   if (!g_gpu_device->RecreateMainSwapChain(wi.value(), vsync_mode, allow_present_throttle,
                                            fullscreen_mode.has_value() ? &fullscreen_mode.value() : nullptr,
diff --git a/src/util/gpu_device.cpp b/src/util/gpu_device.cpp
index 231283c2a..73ecaa862 100644
--- a/src/util/gpu_device.cpp
+++ b/src/util/gpu_device.cpp
@@ -472,6 +472,12 @@ void GPUDevice::Destroy()
   DestroyDevice();
 }
 
+bool GPUDevice::SwitchToSurfacelessRendering(Error* error)
+{
+  // noop on everything except GL because of it's context nonsense
+  return true;
+}
+
 bool GPUDevice::RecreateMainSwapChain(const WindowInfo& wi, GPUVSyncMode vsync_mode, bool allow_present_throttle,
                                       const ExclusiveFullscreenMode* exclusive_fullscreen_mode,
                                       std::optional<bool> exclusive_fullscreen_control, Error* error)
@@ -723,8 +729,7 @@ void GPUDevice::RenderImGui(GPUSwapChain* swap_chain)
     0.0f, 0.0f, static_cast<float>(swap_chain->GetWidth()), static_cast<float>(swap_chain->GetHeight()), 0.0f, 1.0f);
   if (swap_chain->GetPreRotation() != WindowInfo::PreRotation::Identity)
   {
-    mproj =
-      GSMatrix4x4::RotationZ(WindowInfo::GetZRotationForPreRotation(swap_chain->GetPreRotation())) * mproj;
+    mproj = GSMatrix4x4::RotationZ(WindowInfo::GetZRotationForPreRotation(swap_chain->GetPreRotation())) * mproj;
   }
   PushUniformBuffer(&mproj, sizeof(mproj));
 
diff --git a/src/util/gpu_device.h b/src/util/gpu_device.h
index ffcd7fd10..14c46d344 100644
--- a/src/util/gpu_device.h
+++ b/src/util/gpu_device.h
@@ -720,6 +720,7 @@ public:
                                                         const ExclusiveFullscreenMode* exclusive_fullscreen_mode,
                                                         std::optional<bool> exclusive_fullscreen_control,
                                                         Error* error) = 0;
+  virtual bool SwitchToSurfacelessRendering(Error* error);
 
   bool RecreateMainSwapChain(const WindowInfo& wi, GPUVSyncMode vsync_mode, bool allow_present_throttle,
                              const ExclusiveFullscreenMode* exclusive_fullscreen_mode,
diff --git a/src/util/opengl_context_egl.cpp b/src/util/opengl_context_egl.cpp
index a2ddc9061..2d7f9addb 100644
--- a/src/util/opengl_context_egl.cpp
+++ b/src/util/opengl_context_egl.cpp
@@ -8,6 +8,8 @@
 #include "common/error.h"
 #include "common/log.h"
 
+#include "glad/gl.h"
+
 #include <atomic>
 #include <cstring>
 #include <optional>
@@ -164,7 +166,7 @@ EGLSurface OpenGLContextEGL::CreatePlatformSurface(EGLConfig config, const Windo
 
 bool OpenGLContextEGL::SupportsSurfaceless() const
 {
-  return GLAD_EGL_KHR_surfaceless_context;
+  return (!IsGLES() || GLAD_GL_OES_surfaceless_context) && GLAD_EGL_KHR_surfaceless_context;
 }
 
 EGLDisplay OpenGLContextEGL::TryGetPlatformDisplay(void* display, EGLenum platform, const char* platform_ext)
@@ -294,7 +296,7 @@ void OpenGLContextEGL::DestroySurface(SurfaceHandle handle)
   EGLSurface surface = (EGLSurface)handle;
   if (m_current_surface == surface)
   {
-    eglMakeCurrent(m_display, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT);
+    eglMakeCurrent(m_display, EGL_NO_SURFACE, EGL_NO_SURFACE, SupportsSurfaceless() ? m_context : EGL_NO_CONTEXT);
     m_current_surface = EGL_NO_SURFACE;
   }
 
diff --git a/src/util/opengl_device.cpp b/src/util/opengl_device.cpp
index 19d20f74f..4b181ffbc 100644
--- a/src/util/opengl_device.cpp
+++ b/src/util/opengl_device.cpp
@@ -637,6 +637,12 @@ std::unique_ptr<GPUSwapChain> OpenGLDevice::CreateSwapChain(const WindowInfo& wi
   return std::make_unique<OpenGLSwapChain>(wi_copy, vsync_mode, allow_present_throttle, surface_handle);
 }
 
+bool OpenGLDevice::SwitchToSurfacelessRendering(Error* error)
+{
+  // We need to switch to surfaceless if we're temporarily destroying, otherwise we can't issue GL commands.
+  return m_gl_context->MakeCurrent(nullptr, error);
+}
+
 std::string OpenGLDevice::GetDriverInfo() const
 {
   const char* gl_vendor = reinterpret_cast<const char*>(glGetString(GL_VENDOR));
diff --git a/src/util/opengl_device.h b/src/util/opengl_device.h
index 4cf1be950..5846b34b0 100644
--- a/src/util/opengl_device.h
+++ b/src/util/opengl_device.h
@@ -52,6 +52,7 @@ public:
                                                 const ExclusiveFullscreenMode* exclusive_fullscreen_mode,
                                                 std::optional<bool> exclusive_fullscreen_control,
                                                 Error* error) override;
+  bool SwitchToSurfacelessRendering(Error* error) override;
   std::unique_ptr<GPUTexture> CreateTexture(u32 width, u32 height, u32 layers, u32 levels, u32 samples,
                                             GPUTexture::Type type, GPUTexture::Format format, GPUTexture::Flags flags,
                                             const void* data = nullptr, u32 data_stride = 0,