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Diffstat (limited to 'examples/quick/scenegraph/textureinthread/threadrenderer.cpp')
| -rw-r--r-- | examples/quick/scenegraph/textureinthread/threadrenderer.cpp | 257 |
1 files changed, 257 insertions, 0 deletions
diff --git a/examples/quick/scenegraph/textureinthread/threadrenderer.cpp b/examples/quick/scenegraph/textureinthread/threadrenderer.cpp new file mode 100644 index 0000000000..90b6b49880 --- /dev/null +++ b/examples/quick/scenegraph/textureinthread/threadrenderer.cpp @@ -0,0 +1,257 @@ +/**************************************************************************** +** +** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies). +** Contact: http://www.qt-project.org/legal +** +** This file is part of the examples of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:BSD$ +** You may use this file under the terms of the BSD license as follows: +** +** "Redistribution and use in source and binary forms, with or without +** modification, are permitted provided that the following conditions are +** met: +** * Redistributions of source code must retain the above copyright +** notice, this list of conditions and the following disclaimer. +** * Redistributions in binary form must reproduce the above copyright +** notice, this list of conditions and the following disclaimer in +** the documentation and/or other materials provided with the +** distribution. +** * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names +** of its contributors may be used to endorse or promote products derived +** from this software without specific prior written permission. +** +** +** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE." +** +** $QT_END_LICENSE$ +** +****************************************************************************/ + +#include "threadrenderer.h" +#include "logorenderer.h" + +#include <QtCore/QMutex> +#include <QtCore/QThread> + +#include <QtGui/QOpenGLContext> +#include <QtGui/QOpenGLFramebufferObject> + +#include <QtQuick/QQuickWindow> +#include <qsgsimpletexturenode.h> + + +/* + * The render thread shares a context with the scene graph and will + * render into two separate FBOs, one to use for display and one + * to use for rendering + */ +class RenderThread : public QThread +{ + Q_OBJECT +public: + RenderThread(const QSize &size) + : m_renderFbo(0) + , m_displayFbo(0) + , m_logoRenderer(0) + , m_size(size) + { + // Since we're using queued connections, we need affinity to the rendering thread. + moveToThread(this); + + // Set up the QOpenGLContext to use for rendering in this thread. It is sharing + // memory space with the GL context of the scene graph. This constructor is called + // during updatePaintNode, so we are currently on the scene graph thread with the + // scene graph's OpenGL context current. + QOpenGLContext *current = QOpenGLContext::currentContext(); + m_context = new QOpenGLContext(); + m_context->setShareContext(current); + m_context->setFormat(current->format()); + m_context->create(); + m_context->moveToThread(this); + + // We need a non-visible surface to make current... + m_fakeSurface = new QWindow(); + m_fakeSurface->setGeometry(0, 0, 64, 64); + m_fakeSurface->setSurfaceType(QWindow::OpenGLSurface); + m_fakeSurface->setFormat(current->format()); + m_fakeSurface->create(); + } + +public slots: + void renderNext() + { + m_context->makeCurrent(m_fakeSurface); + + if (!m_renderFbo) { + // Initialize the buffers and renderer + QOpenGLFramebufferObjectFormat format; + format.setAttachment(QOpenGLFramebufferObject::CombinedDepthStencil); + m_renderFbo = new QOpenGLFramebufferObject(m_size, format); + m_displayFbo = new QOpenGLFramebufferObject(m_size, format); + m_logoRenderer = new LogoRenderer(); + m_logoRenderer->initialize(); + } + + m_renderFbo->bind(); + glViewport(0, 0, m_size.width(), m_size.height()); + + m_logoRenderer->render(); + + // We need to flush the contents to the FBO before posting + // the texture to the other thread, otherwise, we might + // get unexpected results. + glFlush(); + + m_renderFbo->bindDefault(); + qSwap(m_renderFbo, m_displayFbo); + + emit textureReady(m_displayFbo->texture(), m_size); + } + +signals: + void textureReady(int id, const QSize &size); + +private: + QOpenGLFramebufferObject *m_renderFbo; + QOpenGLFramebufferObject *m_displayFbo; + + LogoRenderer *m_logoRenderer; + + QWindow *m_fakeSurface; + QOpenGLContext *m_context; + QSize m_size; +}; + + + +class TextureNode : public QObject, public QSGSimpleTextureNode +{ + Q_OBJECT + +public: + TextureNode(QQuickWindow *window) + : m_id(0) + , m_size(0, 0) + , m_texture(0) + , m_window(window) + { + // Our texture node must have a texture, so use the default 0 texture. + m_texture = m_window->createTextureFromId(0, QSize(1, 1)); + setTexture(m_texture); + setFiltering(QSGTexture::Linear); + } + + ~TextureNode() + { + delete m_texture; + } + +signals: + void textureInUse(); + void pendingNewTexture(); + +public slots: + + // This function gets called on the FBO rendering thread and will store the + // texture id and size and schedule an update on the window. + void newTexture(int id, const QSize &size) { + m_mutex.lock(); + m_id = id; + m_size = size; + m_mutex.unlock(); + + // We cannot call QQuickWindow::update directly here, as this is only allowed + // from the rendering thread or GUI thread. + emit pendingNewTexture(); + } + + + // Before the scene graph starts to render, we update to the pending texture + void prepareNode() { + m_mutex.lock(); + int newId = m_id; + QSize size = m_size; + m_id = 0; + m_mutex.unlock(); + if (newId) { + delete m_texture; + m_texture = m_window->createTextureFromId(newId, size); + setTexture(m_texture); + + // This will notify the rendering thread that the texture is now being rendered + // and it can start rendering to the other one. + emit textureInUse(); + } + } + +private: + + int m_id; + QSize m_size; + + QMutex m_mutex; + + QSGTexture *m_texture; + QQuickWindow *m_window; +}; + + + +ThreadRenderer::ThreadRenderer() +{ + setFlag(ItemHasContents, true); +} + + + +QSGNode *ThreadRenderer::updatePaintNode(QSGNode *oldNode, UpdatePaintNodeData *) +{ + TextureNode *node = static_cast<TextureNode *>(oldNode); + + if (!node) { + node = new TextureNode(window()); + m_renderThread = new RenderThread(QSize(512, 512)); + + /* Set up connections to get the production of FBO textures in sync with vsync on the + * rendering thread. + * + * When a new texture is ready on the rendering thread, we use a direct connection to + * the texture node to let it know a new texture can be used. The node will then + * emit pendingNewTexture which we bind to QQuickWindow::update to schedule a redraw. + * + * When the scene graph starts rendering the next frame, the prepareNode() function + * is used to update the node with the new texture. Once it completes, it emits + * textureInUse() which we connect to the FBO rendering thread's renderNext() to have + * it start producing content into its current "back buffer". + * + * This FBO rendering pipeline is throttled by vsync on the scene graph rendering thread. + */ + connect(m_renderThread, SIGNAL(textureReady(int,QSize)), node, SLOT(newTexture(int,QSize)), Qt::DirectConnection); + connect(node, SIGNAL(pendingNewTexture()), window(), SLOT(update()), Qt::QueuedConnection); + connect(window(), SIGNAL(beforeRendering()), node, SLOT(prepareNode()), Qt::DirectConnection); + connect(node, SIGNAL(textureInUse()), m_renderThread, SLOT(renderNext()), Qt::QueuedConnection); + + // Start the render thread and enter let it process events. + m_renderThread->start(); + + // Get the production of FBO textures started.. + QMetaObject::invokeMethod(m_renderThread, "renderNext", Qt::QueuedConnection); + } + + node->setRect(boundingRect()); + + return node; +} + +#include "threadrenderer.moc" |