D3D12: Fix the rendernode example for multisampling

Show how this can be handled in the custom QSGRenderNode implementation.

Change-Id: Id6f18ca568a4850060f957998532815bce5c4ac5
Reviewed-by: Andy Nichols <andy.nichols@qt.io>

2 files changed, 21 insertions, 1 deletions

diff --git a/examples/quick/scenegraph/rendernode/d3d12renderer.cpp b/examples/quick/scenegraph/rendernode/d3d12renderer.cpp
index bc03720407..b7dc62fe86 100644
--- a/examples/quick/scenegraph/rendernode/d3d12renderer.cpp
+++ b/examples/quick/scenegraph/rendernode/d3d12renderer.cpp
@@ -153,7 +153,20 @@ void D3D12RenderNode::init()
     psoDesc.NumRenderTargets = 1;
     psoDesc.RTVFormats[0] = DXGI_FORMAT_R8G8B8A8_UNORM;
     psoDesc.DSVFormat = DXGI_FORMAT_D24_UNORM_S8_UINT; // not in use due to !DepthEnable, but this would be the correct format otherwise
-    psoDesc.SampleDesc.Count = 1;
+    // We are rendering on the default render target so if the QuickWindow/View
+    // has requested samples > 0 then we have to follow suit.
+    const uint samples = qMax(1, m_item->window()->format().samples());
+    psoDesc.SampleDesc.Count = samples;
+    if (samples > 1) {
+        D3D12_FEATURE_DATA_MULTISAMPLE_QUALITY_LEVELS msaaInfo = {};
+        msaaInfo.Format = psoDesc.RTVFormats[0];
+        msaaInfo.SampleCount = samples;
+        if (SUCCEEDED(m_device->CheckFeatureSupport(D3D12_FEATURE_MULTISAMPLE_QUALITY_LEVELS, &msaaInfo, sizeof(msaaInfo)))) {
+            if (msaaInfo.NumQualityLevels > 0)
+                psoDesc.SampleDesc.Quality = msaaInfo.NumQualityLevels - 1;
+        }
+    }
+
     if (FAILED(m_device->CreateGraphicsPipelineState(&psoDesc, IID_PPV_ARGS(&pipelineState)))) {
         qWarning("Failed to create graphics pipeline state");
         return;
diff --git a/examples/quick/scenegraph/rendernode/main.cpp b/examples/quick/scenegraph/rendernode/main.cpp
index 9128cdc5be..3e1714313e 100644
--- a/examples/quick/scenegraph/rendernode/main.cpp
+++ b/examples/quick/scenegraph/rendernode/main.cpp
@@ -49,6 +49,13 @@ int main(int argc, char **argv)
     qmlRegisterType<CustomRenderItem>("SceneGraphRendering", 2, 0, "CustomRenderItem");
 
     QQuickView view;
+
+    if (QCoreApplication::arguments().contains(QStringLiteral("--multisample"))) {
+        QSurfaceFormat fmt;
+        fmt.setSamples(4);
+        view.setFormat(fmt);
+    }
+
     view.setResizeMode(QQuickView::SizeRootObjectToView);
     view.setSource(QUrl("qrc:///scenegraph/rendernode/main.qml"));
     view.resize(1024, 768);