Fix texture copy when using multiple canvas

Core/Graphics/InternalInclude/Babylon/Graphics/DeviceContext.h

@@ -121,6 +121,9 @@ namespace Babylon::Graphics
         TextureInfo GetTextureInfo(bgfx::TextureHandle handle);
         static bx::AllocatorI& GetDefaultAllocator() { return m_allocator; }
 
+        // call following method when a submit call is associated with the current acquired viewId
+        void InvalidateView();
+        void Blit(bgfx::Encoder& encoder, bgfx::TextureHandle dst, uint16_t dstX, uint16_t dstY, bgfx::TextureHandle src, uint16_t srcX = 0, uint16_t srcY = 0, uint16_t width = UINT16_MAX, uint16_t height = UINT16_MAX);
     private:
         friend UpdateToken;
 
@@ -130,5 +133,8 @@ namespace Babylon::Graphics
         std::mutex m_textureHandleToInfoMutex{};
 
         static inline bx::DefaultAllocator m_allocator{};
+
+        bool m_currentViewIsUsed{false};
+        bgfx::ViewId m_lastAcquiredViewId{bgfx::kInvalidHandle};
     };
 }

Core/Graphics/InternalInclude/Babylon/Graphics/FrameBuffer.h

@@ -41,7 +41,6 @@ namespace Babylon::Graphics
         void SetScissor(bgfx::Encoder& encoder, float x, float y, float width, float height);
         void Submit(bgfx::Encoder& encoder, bgfx::ProgramHandle programHandle, uint8_t flags);
         void SetStencil(bgfx::Encoder& encoder, uint32_t stencilState);
-        void Blit(bgfx::Encoder& encoder, bgfx::TextureHandle dst, uint16_t dstX, uint16_t dstY, bgfx::TextureHandle src, uint16_t srcX = 0, uint16_t srcY = 0, uint16_t width = UINT16_MAX, uint16_t height = UINT16_MAX);
 
         bool HasDepth() const { return m_hasDepth; }
         bool HasStencil() const { return m_hasStencil; }

Core/Graphics/Source/DeviceContext.cpp

@@ -103,7 +103,9 @@ namespace Babylon::Graphics
 
     bgfx::ViewId DeviceContext::AcquireNewViewId(bgfx::Encoder& encoder)
     {
-        return m_graphicsImpl.AcquireNewViewId(encoder);
+        m_currentViewIsUsed = false;
+        m_lastAcquiredViewId = m_graphicsImpl.AcquireNewViewId(encoder);
+        return m_lastAcquiredViewId;
     }
 
     void DeviceContext::AddTexture(bgfx::TextureHandle handle, uint16_t width, uint16_t height, bool hasMips, uint16_t numLayers, bgfx::TextureFormat::Enum format)
@@ -129,4 +131,22 @@ namespace Babylon::Graphics
     {
        return m_graphicsImpl.GetId();
     }
+
+    void DeviceContext::Blit(bgfx::Encoder& encoder, bgfx::TextureHandle dst, uint16_t dstX, uint16_t dstY, bgfx::TextureHandle src, uint16_t srcX, uint16_t srcY, uint16_t width, uint16_t height)
+    {
+        // Increment viewId so blit happens after the last drawcall of the last viewId if drawcall(s) have been submitted to the view.
+        // Otherwise, reuse last acquired viewId to not waste an Id.
+        auto viewId = m_lastAcquiredViewId;
+        if (!m_currentViewIsUsed)
+        {
+            viewId = AcquireNewViewId(encoder);
+            bgfx::touch(viewId);
+        }
+        encoder.blit(viewId, dst, dstX, dstY, src, srcX, srcY, width, height);
+    }
+
+    void DeviceContext::InvalidateView()
+    {
+        m_currentViewIsUsed = true;
+    }
 }

Core/Graphics/Source/FrameBuffer.cpp

@@ -112,6 +112,7 @@ namespace Babylon::Graphics
         m_bgfxScissor = {};
 
         encoder.touch(m_viewId.value());
+        m_deviceContext.InvalidateView();
     }
 
     void FrameBuffer::SetViewPort(bgfx::Encoder& encoder, float x, float y, float width, float height)
@@ -130,13 +131,7 @@ namespace Babylon::Graphics
     {
         SetBgfxViewPortAndScissor(encoder, m_desiredViewPort, m_desiredScissor);
         encoder.submit(m_viewId.value(), programHandle, 0, flags);
-    }
-
-    void FrameBuffer::Blit(bgfx::Encoder& encoder, bgfx::TextureHandle dst, uint16_t dstX, uint16_t dstY, bgfx::TextureHandle src, uint16_t srcX, uint16_t srcY, uint16_t width, uint16_t height)
-    {
-        // In order for Blit to work properly we need to force the creation of a new ViewID.
-        SetBgfxViewPortAndScissor(encoder, m_desiredViewPort, m_desiredScissor);
-        encoder.blit(m_viewId.value(), dst, dstX, dstY, src, srcX, srcY, width, height);
+        m_deviceContext.InvalidateView();
     }
 
     void FrameBuffer::SetStencil(bgfx::Encoder& encoder, uint32_t stencilState)

Plugins/NativeEngine/Source/NativeEngine.cpp

@@ -1434,7 +1434,7 @@ namespace Babylon
         const auto textureSource = data.ReadPointer<Graphics::Texture>();
         const auto textureDestination = data.ReadPointer<Graphics::Texture>();
 
-        GetBoundFrameBuffer(*encoder).Blit(*encoder, textureDestination->Handle(), 0, 0, textureSource->Handle());
+        m_deviceContext.Blit(*encoder, textureDestination->Handle(), 0, 0, textureSource->Handle());
     }
 
     void NativeEngine::LoadRawTexture(const Napi::CallbackInfo& info)