Robust view resize via modification counting

include/vsg/app/View.h

@@ -35,6 +35,8 @@ namespace vsg
     class VSG_DECLSPEC View : public Inherit<Group, View>
     {
     public:
+        static ModifiedCount modifiedCount(uint32_t viewID);
+
         View(ViewFeatures in_features = RECORD_ALL);
 
         // share the specified view's children, viewID, mask and camera ViewportState
@@ -63,6 +65,10 @@ namespace vsg
         /// share the specified view's viewID, mask, camera ViewportState, with this View
         void share(const View& view);
 
+        /// incremented when the pipeline state for the viewID is invalidated
+        ModifiedCount modifiedCount();
+        void modified();
+
         /// camera controls the viewport state and projection and view matrices
         ref_ptr<Camera> camera;
 

include/vsg/state/GraphicsPipeline.h

@@ -95,6 +95,8 @@ namespace vsg
 
             virtual ~Implementation();
 
+            ModifiedCount viewModifiedCount;
+
             VkPipeline _pipeline;
 
             ref_ptr<Device> _device;

src/vsg/app/View.cpp

@@ -22,6 +22,8 @@ using namespace vsg;
 // thread safe container for managing the deviceID for each vsg::View
 static std::mutex s_ViewCountMutex;
 static std::vector<uint32_t> s_ActiveViews;
+// these must not be reset to zero when a view ID is reused
+static std::vector<ModifiedCount> s_ViewIDModifiedCounts;
 
 static uint32_t getUniqueViewID()
 {
@@ -38,6 +40,7 @@ static uint32_t getUniqueViewID()
     }
 
     s_ActiveViews.push_back(1);
+    s_ViewIDModifiedCounts.emplace_back();
 
     return viewID;
 }
@@ -62,6 +65,12 @@ static void releaseViewID(uint32_t viewID)
 {
     std::scoped_lock<std::mutex> guard(s_ViewCountMutex);
     --s_ActiveViews[viewID];
+    ++s_ViewIDModifiedCounts[viewID];
+}
+
+ModifiedCount vsg::View::modifiedCount(uint32_t viewID)
+{
+    return s_ViewIDModifiedCounts[viewID];
 }
 
 //////////////////////////////////////////////////////////////////////////////////////////////////////////////
@@ -125,3 +134,13 @@ void View::share(const View& view)
         camera->viewportState = view.camera->viewportState;
     }
 }
+
+ModifiedCount vsg::View::modifiedCount()
+{
+    return s_ViewIDModifiedCounts[viewID];
+}
+
+void vsg::View::modified()
+{
+    ++s_ViewIDModifiedCounts[viewID];
+}

src/vsg/app/WindowResizeHandler.cpp

@@ -45,7 +45,6 @@ void UpdateGraphicsPipelines::apply(vsg::BindGraphicsPipeline& bindPipeline)
     auto pipeline = bindPipeline.pipeline;
     if (pipeline)
     {
-        pipeline->release(context->viewID);
         pipeline->compile(*context);
     }
 }
@@ -118,7 +117,6 @@ void WindowResizeHandler::apply(vsg::BindGraphicsPipeline& bindPipeline)
         bool needToRegenerateGraphicsPipeline = !containsViewport(*graphicsPipeline);
         if (needToRegenerateGraphicsPipeline)
         {
-            graphicsPipeline->release(context->viewID);
             graphicsPipeline->compile(*context);
         }
     }
@@ -144,11 +142,13 @@ void WindowResizeHandler::apply(vsg::View& view)
 {
     if (!visit(&view)) return;
 
+    auto previous_viewID = context->viewID;
     context->viewID = view.viewID;
 
     if (!view.camera)
     {
         view.traverse(*this);
+        context->viewID = previous_viewID;
         return;
     }
 
@@ -178,9 +178,12 @@ void WindowResizeHandler::apply(vsg::View& view)
         }
     }
 
+    view.modified();
+
     context->defaultPipelineStates.emplace_back(viewportState);
 
     view.traverse(*this);
 
     context->defaultPipelineStates.pop_back();
+    context->viewID = previous_viewID;
 }

src/vsg/state/GraphicsPipeline.cpp

@@ -10,6 +10,7 @@ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLI
 
 </editor-fold> */
 
+#include <vsg/app/View.h>
 #include <vsg/core/Exception.h>
 #include <vsg/core/compare.h>
 #include <vsg/io/Logger.h>
@@ -138,7 +139,7 @@ void GraphicsPipeline::compile(Context& context)
         _implementation.resize(viewID + 1);
     }
 
-    if (!_implementation[viewID])
+    if (!_implementation[viewID] || _implementation[viewID]->viewModifiedCount != View::modifiedCount(context.viewID))
     {
         // compile shaders if required
         bool requiresShaderCompiler = false;
@@ -189,6 +190,7 @@ void GraphicsPipeline::compile(Context& context)
 // GraphicsPipeline::Implementation
 //
 GraphicsPipeline::Implementation::Implementation(Context& context, Device* device, const RenderPass* renderPass, const PipelineLayout* pipelineLayout, const ShaderStages& shaderStages, const GraphicsPipelineStates& pipelineStates, uint32_t subpass) :
+    viewModifiedCount(View::modifiedCount(context.viewID)),
     _device(device)
 {
     VkGraphicsPipelineCreateInfo pipelineInfo = {};