Renderer: fix/improvements

Restore the default render state after having submitted the RenderViews
After having executed the RenderCommands, restore the RenderView state
Minimize calls by merged the RenderView state with the RenderCommands states.

Change-Id: Ice8272b18a0c45f97f4571d9d782a54b221d6cc9
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>

1 files changed, 28 insertions, 9 deletions

diff --git a/src/render/backend/renderer.cpp b/src/render/backend/renderer.cpp
index ce9026687..833ab07e9 100644
--- a/src/render/backend/renderer.cpp
+++ b/src/render/backend/renderer.cpp
@@ -687,8 +687,10 @@ void Renderer::submitRenderViews()
         // If the RenderView has a RenderStateSet defined
         const RenderView *renderView = renderViews.at(i);
 
-        if (renderView->stateSet())
-            m_graphicsContext->setCurrentStateSet(renderView->stateSet());
+        // Set RenderView render state
+        RenderStateSet *renderViewStateSet = renderView->stateSet();
+        if (renderViewStateSet)
+            m_graphicsContext->setCurrentStateSet(renderViewStateSet);
 
         // Set RenderTarget ...
         // Activate RenderTarget
@@ -709,11 +711,20 @@ void Renderer::submitRenderViews()
         // Execute the render commands
         executeCommands(renderView->commands());
 
+        // executeCommands takes care of restoring the stateset to the value
+        // of gc->currentContext() at the moment it was called (either
+        // renderViewStateSet or m_defaultRenderStateSet)
+
         frameElapsed = timer.elapsed() - frameElapsed;
         qCDebug(Rendering) << Q_FUNC_INFO << "Submitted Renderview " << i + 1 << "/" << renderViewsCount  << "in " << frameElapsed << "ms";
         frameElapsed = timer.elapsed();
     }
 
+    // Reset state to the default state if the last stateset is not the
+    // defaultRenderStateSet
+    if (m_graphicsContext->currentStateSet() != m_defaultRenderStateSet)
+        m_graphicsContext->setCurrentStateSet(m_defaultRenderStateSet);
+
     m_graphicsContext->endDrawing(boundFboId == m_graphicsContext->defaultFBO());
 
     // Delete all the RenderViews which will clear the allocators
@@ -767,6 +778,9 @@ void Renderer::executeCommands(const QVector<RenderCommand *> &commands)
     // Use the graphicscontext to submit the commands to the underlying
     // graphics API (OpenGL)
 
+    // Save the RenderView base stateset
+    RenderStateSet *globalState = m_graphicsContext->currentStateSet();
+
     Q_FOREACH (RenderCommand *command, commands) {
 
         QMeshData *meshData = m_meshDataManager->data(command->m_meshData);
@@ -838,10 +852,16 @@ void Renderer::executeCommands(const QVector<RenderCommand *> &commands)
 
         //// Draw Calls
         // Set state
-        RenderStateSet *globalState = m_graphicsContext->currentStateSet();
-        if (command->m_stateSet != Q_NULLPTR)
-            m_graphicsContext->setCurrentStateSet(command->m_stateSet);
+        RenderStateSet *localState = command->m_stateSet;
 
+        // Merge the RenderCommand state with the globalState of the RenderView
+        // Or restore the globalState if no stateSet for the RenderCommand
+        if (localState != Q_NULLPTR) {
+            command->m_stateSet->merge(globalState);
+            m_graphicsContext->setCurrentStateSet(command->m_stateSet);
+        } else {
+            m_graphicsContext->setCurrentStateSet(globalState);
+        }
         // All Uniforms for a pass are stored in the QUniformPack of the command
         // Uniforms for Effect, Material and Technique should already have been correctly resolved
         // at that point
@@ -865,10 +885,6 @@ void Renderer::executeCommands(const QVector<RenderCommand *> &commands)
                 m_graphicsContext->drawArrays(primType, 0, primCount);
             }
 
-            // Reset state if overridden by pass state
-            if (command->m_stateSet != Q_NULLPTR)
-                m_graphicsContext->setCurrentStateSet(globalState);
-
             int err = m_graphicsContext->openGLContext()->functions()->glGetError();
             if (err)
                 qCWarning(Rendering) << "GL error after drawing mesh:" << QString::number(err, 16);
@@ -877,6 +893,9 @@ void Renderer::executeCommands(const QVector<RenderCommand *> &commands)
                 vao->release();
         }
     }
+
+    // Reset to the state we were in before executing the render commands
+    m_graphicsContext->setCurrentStateSet(globalState);
 }
 
 void Renderer::addAllocator(QFrameAllocator *allocator)