Delete abandoned VAOs after each frame

Use a job to traverse all active VAO handles to check if the
geometry and shader objects used to identify the VAO do stil exist.
If not, let the renderer dispose the VAOs.

Make sure to synchronize access to VAO state and hide state changes
behind member functions.

Change-Id: Ib77be67d55daa61885cd914af8d9cfc622cae940
Reviewed-by: Paul Lemire <paul.lemire@kdab.com>

1 files changed, 38 insertions, 8 deletions

diff --git a/src/render/backend/renderer.cpp b/src/render/backend/renderer.cpp
index d38df13e2..100c4a33d 100644
--- a/src/render/backend/renderer.cpp
+++ b/src/render/backend/renderer.cpp
@@ -170,6 +170,7 @@ Renderer::Renderer(QRenderAspect::RenderType type)
     , m_updateMeshTriangleListJob(Render::UpdateMeshTriangleListJobPtr::create())
     , m_filterCompatibleTechniqueJob(Render::FilterCompatibleTechniqueJobPtr::create())
     , m_bufferGathererJob(Render::GenericLambdaJobPtr<std::function<void ()>>::create([this] { lookForDirtyBuffers(); }, JobTypes::DirtyBufferGathering))
+    , m_vaoGathererJob(Render::GenericLambdaJobPtr<std::function<void ()>>::create([this] { lookForAbandonedVaos(); }, JobTypes::DirtyVaoGathering))
     , m_textureGathererJob(Render::GenericLambdaJobPtr<std::function<void ()>>::create([this] { lookForDirtyTextures(); }, JobTypes::DirtyTextureGathering))
     , m_shaderGathererJob(Render::GenericLambdaJobPtr<std::function<void ()>>::create([this] { lookForDirtyShaders(); }, JobTypes::DirtyShaderGathering))
     , m_syncTextureLoadingJob(Render::GenericLambdaJobPtr<std::function<void ()>>::create([] {}, JobTypes::SyncTextureLoading))
@@ -831,6 +832,23 @@ void Renderer::prepareCommandsSubmission(const QVector<RenderView *> &renderView
 }
 
 // Executed in a job
+void Renderer::lookForAbandonedVaos()
+{
+    const QVector<HVao> activeVaos = m_nodesManager->vaoManager()->activeHandles();
+    for (HVao handle : activeVaos) {
+        OpenGLVertexArrayObject *vao = m_nodesManager->vaoManager()->data(handle);
+
+        // Make sure to only mark VAOs for deletion that were already created
+        // (ignore those that might be currently under construction in the render thread)
+        if (vao->isAbandoned(m_nodesManager->geometryManager(), m_nodesManager->shaderManager())) {
+            m_abandonedVaosMutex.lock();
+            m_abandonedVaos.push_back(handle);
+            m_abandonedVaosMutex.unlock();
+        }
+    }
+}
+
+// Executed in a job
 void Renderer::lookForDirtyBuffers()
 {
     const QVector<HBuffer> activeBufferHandles = m_nodesManager->bufferManager()->activeHandles();
@@ -923,8 +941,6 @@ void Renderer::updateGLResources()
         // We can really release the texture at this point
         m_nodesManager->textureManager()->releaseResource(textureCleanedUpId);
     }
-
-
 }
 
 // Render Thread
@@ -1267,6 +1283,7 @@ QVector<Qt3DCore::QAspectJobPtr> Renderer::renderBinJobs()
 
     // Jobs to prepare GL Resource upload
     renderBinJobs.push_back(m_syncTextureLoadingJob);
+    renderBinJobs.push_back(m_vaoGathererJob);
     renderBinJobs.push_back(m_bufferGathererJob);
     renderBinJobs.push_back(m_textureGathererJob);
     renderBinJobs.push_back(m_shaderGathererJob);
@@ -1368,16 +1385,15 @@ void Renderer::createOrUpdateVAO(RenderCommand *command,
                                  HVao *previousVaoHandle,
                                  OpenGLVertexArrayObject **vao)
 {
+    const VAOIdentifier vaoKey(command->m_geometry, command->m_shader);
+
     VAOManager *vaoManager = m_nodesManager->vaoManager();
-    command->m_vao = vaoManager->lookupHandle(QPair<HGeometry, HShader>(command->m_geometry, command->m_shader));
+    command->m_vao = vaoManager->lookupHandle(vaoKey);
 
     if (command->m_vao.isNull()) {
         qCDebug(Rendering) << Q_FUNC_INFO << "Allocating new VAO";
-        command->m_vao = vaoManager->getOrAcquireHandle(QPair<HGeometry, HShader>(command->m_geometry, command->m_shader));
-        vaoManager->data(command->m_vao)->setGraphicsContext(m_graphicsContext.data());
-        if (m_graphicsContext->supportsVAO())
-            vaoManager->data(command->m_vao)->setVao(new QOpenGLVertexArrayObject());
-        vaoManager->data(command->m_vao)->create();
+        command->m_vao = vaoManager->getOrAcquireHandle(vaoKey);
+        vaoManager->data(command->m_vao)->create(m_graphicsContext.data(), vaoKey);
     }
 
     if (*previousVaoHandle != command->m_vao) {
@@ -1573,6 +1589,20 @@ void Renderer::cleanGraphicsResources()
         tex->destroyGLTexture();
         delete tex;
     }
+
+    // Delete abandoned VAOs
+    m_abandonedVaosMutex.lock();
+    const QVector<HVao> abandonedVaos = std::move(m_abandonedVaos);
+    m_abandonedVaosMutex.unlock();
+    for (HVao vaoHandle : abandonedVaos) {
+        // might have already been destroyed last frame, but added by the cleanup job before, so
+        // check if the VAO is really still existent
+        OpenGLVertexArrayObject *vao = m_nodesManager->vaoManager()->data(vaoHandle);
+        if (vao) {
+            vao->destroy();
+            m_nodesManager->vaoManager()->release(vaoHandle);
+        }
+    }
 }
 
 QList<QMouseEvent> Renderer::pendingPickingEvents() const