IDeviceContextGL: OpenGL interop improvements.

Add `PurgeCurrentContextCaches()` method;
Remove `PurgeCaches` parameter of  `UpdateCurrentGLContext()`.

Graphics/GraphicsEngineOpenGL/include/DeviceContextGLImpl.hpp

@@ -293,7 +293,10 @@ class DeviceContextGLImpl final : public DeviceContextBase<EngineGLImplTraits>
     virtual void DILIGENT_CALL_TYPE BindSparseResourceMemory(const BindSparseResourceMemoryAttribs& Attribs) override final;
 
     /// Implementation of IDeviceContextGL::UpdateCurrentGLContext().
-    virtual bool DILIGENT_CALL_TYPE UpdateCurrentGLContext(bool PurgeCaches) override final;
+    virtual bool DILIGENT_CALL_TYPE UpdateCurrentGLContext() override final;
+
+    /// Implementation of IDeviceContextGL::PurgeCurrentContextCaches().
+    virtual void DILIGENT_CALL_TYPE PurgeCurrentContextCaches() override final;
 
     GLContextState& GetContextState() { return m_ContextState; }
 

Graphics/GraphicsEngineOpenGL/include/FBOCache.hpp

@@ -72,6 +72,8 @@ class FBOCache
 
     void OnReleaseTexture(ITexture* pTexture);
 
+    void Clear();
+
 private:
     // This structure is used as the key to find FBO
     struct FBOCacheKey

Graphics/GraphicsEngineOpenGL/include/VAOCache.hpp

@@ -71,6 +71,9 @@ class VAOCache
     void OnDestroyBuffer(const BufferGLImpl& Buffer);
     void OnDestroyPSO(const PipelineStateGLImpl& PSO);
 
+    // Clears all cached objects
+    void Clear();
+
 private:
     // This structure is used as the key to find VAO
     struct VAOHashKey

Graphics/GraphicsEngineOpenGL/interface/DeviceContextGL.h

@@ -58,14 +58,15 @@ DILIGENT_BEGIN_INTERFACE(IDeviceContextGL, IDeviceContext)
     /// other command to let the engine update active context every time when control flow
     /// is passed over from the main application.
     ///
-    /// \param[in] PurgeCaches - Whether to purge context caches (e.g. VAO, FBO) before
-    ///                          updating the active context. An application should set this
-    ///                          flag to true if the last active context will not be used anymore
-    ///                          (e.g. it was destroyed) to avoid memory leaks.
-    /// 
     /// \return     false if there is no active GL context, and true otherwise.
-    VIRTUAL bool METHOD(UpdateCurrentGLContext)(THIS_
-                                                bool PurgeCaches DEFAULT_INITIALIZER(false)) PURE;
+    VIRTUAL bool METHOD(UpdateCurrentGLContext)(THIS_) PURE;
+
+    /// Purge current context caches (e.g. VAO, FBO).
+
+    /// If an application uses multiple GL contexts, this method must be called
+    /// before the current context is about to be released,
+    /// to let the engine cleanup internal OpenGL object caches.
+    VIRTUAL void METHOD(PurgeCurrentContextCaches)(THIS_) PURE;
 
     /// Sets the swap in the device context. The swap chain is used by the device context
     /// to obtain the default FBO handle.

Graphics/GraphicsEngineOpenGL/src/DeviceContextGLImpl.cpp

@@ -1653,13 +1653,8 @@ void DeviceContextGLImpl::EndQuery(IQuery* pQuery)
     }
 }
 
-bool DeviceContextGLImpl::UpdateCurrentGLContext(bool PurgeCaches)
+bool DeviceContextGLImpl::UpdateCurrentGLContext()
 {
-    if (PurgeCaches)
-    {
-        m_pDevice->PurgeContextCaches(m_ContextState.GetCurrentGLContext());
-    }
-
     auto NativeGLContext = m_pDevice->m_GLContext.GetCurrentNativeGLContext();
     if (NativeGLContext == NULL)
         return false;
@@ -1668,6 +1663,13 @@ bool DeviceContextGLImpl::UpdateCurrentGLContext(bool PurgeCaches)
     return true;
 }
 
+void DeviceContextGLImpl::PurgeCurrentContextCaches()
+{
+    auto NativeGLContext = m_pDevice->m_GLContext.GetCurrentNativeGLContext();
+    if (NativeGLContext != NULL)
+        m_pDevice->PurgeContextCaches(NativeGLContext);
+}
+
 void DeviceContextGLImpl::UpdateBuffer(IBuffer*                       pBuffer,
                                        Uint64                         Offset,
                                        Uint64                         Size,

Graphics/GraphicsEngineOpenGL/src/FBOCache.cpp

@@ -115,6 +115,14 @@ void FBOCache::OnReleaseTexture(ITexture* pTexture)
     m_TexIdToKey.erase(EqualRange.first, EqualRange.second);
 }
 
+void FBOCache::Clear()
+{
+    Threading::SpinLockGuard CacheGuard{m_CacheLock};
+
+    m_Cache.clear();
+    m_TexIdToKey.clear();
+}
+
 GLObjectWrappers::GLFrameBufferObj FBOCache::CreateFBO(GLContextState&    ContextState,
                                                        Uint32             NumRenderTargets,
                                                        TextureViewGLImpl* ppRTVs[],

Graphics/GraphicsEngineOpenGL/src/RenderDeviceGLImpl.cpp

@@ -1687,11 +1687,23 @@ void RenderDeviceGLImpl::PurgeContextCaches(GLContext::NativeGLContextType Conte
 {
     {
         Threading::SpinLockGuard FBOCacheGuard{m_FBOCacheLock};
-        m_FBOCache.erase(Context);
+
+        auto it = m_FBOCache.find(Context);
+        if (it != m_FBOCache.end())
+        {
+            it->second.Clear();
+            m_FBOCache.erase(it);
+        }
     }
     {
         Threading::SpinLockGuard VAOCacheGuard{m_VAOCacheLock};
-        m_VAOCache.erase(Context);
+
+        auto it = m_VAOCache.find(Context);
+        if (it != m_VAOCache.end())
+        {
+            it->second.Clear();
+            m_VAOCache.erase(it);
+        }
     }
 }
 

Graphics/GraphicsEngineOpenGL/src/VAOCache.cpp

@@ -105,6 +105,15 @@ void VAOCache::OnDestroyPSO(const PipelineStateGLImpl& PSO)
     ClearStaleKeys(StaleKeys);
 }
 
+void VAOCache::Clear()
+{
+    Threading::SpinLockGuard CacheGuard{m_CacheLock};
+
+    m_Cache.clear();
+    m_PSOToKey.clear();
+    m_BuffToKey.clear();
+}
+
 void VAOCache::ClearStaleKeys(const std::vector<VAOHashKey>& StaleKeys)
 {
     // Collect unique PSOs and buffers used in stale keys.