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++ // Copyright (C) 2026 The Qt Company Ltd.
++ // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only
++
++ #include <QTest>
++
++ #include <private/qquick3dviewport_p.h>
++ #include <ssg/qssgrendercontextcore.h>
++ #include <QtQuick3DRuntimeRender/private/qssgrhicontext_p.h>
++
++ #if QT_CONFIG(vulkan)
++ #include <QVulkanInstance>
++ #endif
++
++ #include "../shared/util.h"
++
++ class tst_MaterialSwap : public QQuick3DDataTest
++ {
++ Q_OBJECT
++
++ private slots:
++ void initTestCase() override;
++ void swapDoesNotGrowDrawCallData();
++ void skyMaterialSwapDoesNotGrowDrawCallData();
++
++ private:
++ void runSwapTest(const QString &qmlFile);
++ #if QT_CONFIG(vulkan)
++ QVulkanInstance vulkanInstance;
++ #endif
++ };
++
++ void tst_MaterialSwap::initTestCase()
++ {
++ QQuick3DDataTest::initTestCase();
++ if (!initialized())
++ return;
++
++ #if QT_CONFIG(vulkan)
++ vulkanInstance.setLayers({ "VK_LAYER_LUNARG_standard_validation" });
++ vulkanInstance.create(); // may fail, which is fine if Vulkan is not used in the first place
++ #endif
++ }
++
++ void tst_MaterialSwap::swapDoesNotGrowDrawCallData()
++ {
++ runSwapTest(QString::fromLatin1("materialSwap.qml"));
++ }
++
++ void tst_MaterialSwap::skyMaterialSwapDoesNotGrowDrawCallData()
++ {
++ runSwapTest(QString::fromLatin1("skyMaterialSwap.qml"));
++ }
++
++ void tst_MaterialSwap::runSwapTest(const QString &qmlFile)
++ {
++ QQuick3DTestOffscreenRenderer renderer;
++ void *vulkanInstancePtr = nullptr;
++ #if QT_CONFIG(vulkan)
++ vulkanInstancePtr = &vulkanInstance;
++ #endif
++ QVERIFY(renderer.init(testFileUrl(qmlFile), vulkanInstancePtr));
++
++ #ifdef Q_OS_MACOS
++ if (renderer.quickWindow->rendererInterface()->graphicsApi() == QSGRendererInterface::OpenGL)
++ QSKIP("Skipping test due to software OpenGL renderer problems on macOS");
++ #endif
++
++ renderer.renderNextFrame();
++
++ const auto &context = QQuick3DSceneManager::getOrSetWindowAttachment(*renderer.quickWindow)->rci();
++ QVERIFY(context);
++
++ const auto &rhiContext = context->rhiContext();
++ QVERIFY(rhiContext);
++ const QSSGRhiContextPrivate *rhiCtxD = QSSGRhiContextPrivate::get(rhiContext.get());
++
++ const auto swapAndRenderFrame = [&](bool swapped) {
++ renderer.rootItem->setProperty("swapped", swapped);
++ renderer.renderNextFrame();
++ };
++
++ // Warm up so both materials have been through creation, destruction and
++ // re-creation at least once; the sizes after this represent the expected
++ // steady state (entries for the currently assigned material, plus at most
++ // one swap's worth of not-yet-cleaned-up entries).
++ for (int i = 1; i <= 4; ++i)
++ swapAndRenderFrame(i % 2 != 0);
++
++ const qsizetype baselineDrawCallData = rhiCtxD->m_drawCallData.size();
++ const qsizetype baselineSrbCache = rhiCtxD->m_srbCache.size();
++ QVERIFY(baselineDrawCallData > 0);
++
++ constexpr int SwapCount = 20;
++ for (int i = 1; i <= SwapCount; ++i)
++ swapAndRenderFrame(i % 2 == 0);
++
++ // Without the cleanup of material-keyed draw call data the caches grow by
++ // at least one entry per swap; with it the sizes stay at the steady state.
++ // Allow a little slack so the test does not depend on the exact frame at
++ // which the deferred cleanup of the previous material runs.
++ constexpr qsizetype Slack = 4;
++ const qsizetype finalDrawCallData = rhiCtxD->m_drawCallData.size();
++ const qsizetype finalSrbCache = rhiCtxD->m_srbCache.size();
++ QVERIFY2(finalDrawCallData <= baselineDrawCallData + Slack,
++ qPrintable(QString::fromLatin1("m_drawCallData grew from %1 to %2 entries over %3 material swaps")
++ .arg(baselineDrawCallData).arg(finalDrawCallData).arg(SwapCount)));
++ QVERIFY2(finalSrbCache <= baselineSrbCache + Slack,
++ qPrintable(QString::fromLatin1("m_srbCache grew from %1 to %2 entries over %3 material swaps")
++ .arg(baselineSrbCache).arg(finalSrbCache).arg(SwapCount)));
++ }
++
++ QTEST_MAIN(tst_MaterialSwap)
++ #include "tst_materialswap.moc"