qopenglvertexarrayobject.cpp

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// Copyright (C) 2014 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Sean Harmer <sean.harmer@kdab.com>
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
#include "qopenglvertexarrayobject.h"
 
#include <QtCore/private/qobject_p.h>
#include <QtCore/qthread.h>
#include <QtGui/qopenglcontext.h>
#include <QtGui/qoffscreensurface.h>
#include <QtGui/qguiapplication.h>
 
#include <QtOpenGL/QOpenGLVersionFunctionsFactory>
 
#if !QT_CONFIG(opengles2)
#  include <QtOpenGL/qopenglfunctions_3_0.h>
#  include <QtOpenGL/qopenglfunctions_3_2_core.h>
#endif
 
#include <private/qopenglcontext_p.h>
#include <private/qopenglextensions_p.h>
#include <private/qopenglvertexarrayobject_p.h>
 
QT_BEGIN_NAMESPACE
 
class QOpenGLFunctions_3_0;
class QOpenGLFunctions_3_2_Core;
 
static void vertexArrayObjectHelperDestroyCallback(QOpenGLVertexArrayObjectHelper *vaoHelper)
{
    delete vaoHelper;
}
 
QOpenGLVertexArrayObjectHelper *QOpenGLVertexArrayObjectHelper::vertexArrayObjectHelperForContext(QOpenGLContext *context)
{
    Q_ASSERT(context);
 
    auto contextPrivate = QOpenGLContextPrivate::get(context);
    auto &vaoHelper = contextPrivate->vaoHelper;
 
    if (!vaoHelper) {
        vaoHelper = new QOpenGLVertexArrayObjectHelper(context);
        contextPrivate->vaoHelperDestroyCallback = &vertexArrayObjectHelperDestroyCallback;
    }
 
    return vaoHelper;
}
 
void QOpenGLVertexArrayObjectHelper::initializeFromContext(QOpenGLContext *context)
{
    Q_ASSERT(context);
 
    bool tryARB = true;
 
    if (context->isOpenGLES()) {
        if (context->format().majorVersion() >= 3) {
            QOpenGLExtraFunctionsPrivate *extra = static_cast<QOpenGLExtensions *>(context->extraFunctions())->d();
            GenVertexArrays = extra->f.GenVertexArrays;
            DeleteVertexArrays = extra->f.DeleteVertexArrays;
            BindVertexArray = extra->f.BindVertexArray;
            IsVertexArray = extra->f.IsVertexArray;
            tryARB = false;
        } else if (context->hasExtension(QByteArrayLiteral("GL_OES_vertex_array_object"))) {
            GenVertexArrays = reinterpret_cast<QOpenGLVertexArrayObjectHelper::qt_GenVertexArrays_t>(context->getProcAddress("glGenVertexArraysOES"));
            DeleteVertexArrays = reinterpret_cast<QOpenGLVertexArrayObjectHelper::qt_DeleteVertexArrays_t>(context->getProcAddress("glDeleteVertexArraysOES"));
            BindVertexArray = reinterpret_cast<QOpenGLVertexArrayObjectHelper::qt_BindVertexArray_t>(context->getProcAddress("glBindVertexArrayOES"));
            IsVertexArray = reinterpret_cast<QOpenGLVertexArrayObjectHelper::qt_IsVertexArray_t>(context->getProcAddress("glIsVertexArrayOES"));
            tryARB = false;
        }
    } else if (context->hasExtension(QByteArrayLiteral("GL_APPLE_vertex_array_object")) &&
               !context->hasExtension(QByteArrayLiteral("GL_ARB_vertex_array_object"))) {
        GenVertexArrays = reinterpret_cast<QOpenGLVertexArrayObjectHelper::qt_GenVertexArrays_t>(context->getProcAddress("glGenVertexArraysAPPLE"));
        DeleteVertexArrays = reinterpret_cast<QOpenGLVertexArrayObjectHelper::qt_DeleteVertexArrays_t>(context->getProcAddress("glDeleteVertexArraysAPPLE"));
        BindVertexArray = reinterpret_cast<QOpenGLVertexArrayObjectHelper::qt_BindVertexArray_t>(context->getProcAddress("glBindVertexArrayAPPLE"));
        IsVertexArray = reinterpret_cast<QOpenGLVertexArrayObjectHelper::qt_IsVertexArray_t>(context->getProcAddress("glIsVertexArrayAPPLE"));
        tryARB = false;
    }
 
    if (tryARB && context->hasExtension(QByteArrayLiteral("GL_ARB_vertex_array_object"))) {
        GenVertexArrays = reinterpret_cast<QOpenGLVertexArrayObjectHelper::qt_GenVertexArrays_t>(context->getProcAddress("glGenVertexArrays"));
        DeleteVertexArrays = reinterpret_cast<QOpenGLVertexArrayObjectHelper::qt_DeleteVertexArrays_t>(context->getProcAddress("glDeleteVertexArrays"));
        BindVertexArray = reinterpret_cast<QOpenGLVertexArrayObjectHelper::qt_BindVertexArray_t>(context->getProcAddress("glBindVertexArray"));
        IsVertexArray = reinterpret_cast<QOpenGLVertexArrayObjectHelper::qt_IsVertexArray_t>(context->getProcAddress("glIsVertexArray"));
    }
}
 
class QOpenGLVertexArrayObjectPrivate : public QObjectPrivate
{
public:
    QOpenGLVertexArrayObjectPrivate()
        : vao(0)
        , vaoFuncsType(NotSupported)
        , context(nullptr)
        , guiThread(nullptr)
    {
    }
 
    bool create();
    void destroy();
    void bind();
    void release();
    void _q_contextAboutToBeDestroyed();
 
    Q_DECLARE_PUBLIC(QOpenGLVertexArrayObject)
 
    GLuint vao;
 
    union {
        QOpenGLFunctions_3_0 *core_3_0;
        QOpenGLFunctions_3_2_Core *core_3_2;
        QOpenGLVertexArrayObjectHelper *helper;
    } vaoFuncs;
    enum {
        NotSupported,
        Core_3_0,
        Core_3_2,
        ARB,
        APPLE,
        OES
    } vaoFuncsType;
 
    QOpenGLContext *context;
    QThread *guiThread;
};
 
bool QOpenGLVertexArrayObjectPrivate::create()
{
    if (vao) {
        qWarning("QOpenGLVertexArrayObject::create() VAO is already created");
        return false;
    }
 
    Q_Q(QOpenGLVertexArrayObject);
 
    QOpenGLContext *ctx = QOpenGLContext::currentContext();
    if (!ctx) {
        qWarning("QOpenGLVertexArrayObject::create() requires a valid current OpenGL context");
        return false;
    }
 
    //Fail early, if context is the same as ctx, it means we have tried to initialize for this context and failed
    if (ctx == context)
        return false;
 
    context = ctx;
    QObject::connect(context, SIGNAL(aboutToBeDestroyed()), q, SLOT(_q_contextAboutToBeDestroyed()));
 
    guiThread = qGuiApp->thread();
 
    if (ctx->isOpenGLES()) {
        if (ctx->format().majorVersion() >= 3 || ctx->hasExtension(QByteArrayLiteral("GL_OES_vertex_array_object"))) {
            vaoFuncs.helper = QOpenGLVertexArrayObjectHelper::vertexArrayObjectHelperForContext(ctx);
            vaoFuncsType = OES;
            vaoFuncs.helper->glGenVertexArrays(1, &vao);
        }
    } else {
        vaoFuncs.core_3_0 = nullptr;
        vaoFuncsType = NotSupported;
        QSurfaceFormat format = ctx->format();
#if !QT_CONFIG(opengles2)
        if (format.version() >= qMakePair(3,2)) {
            vaoFuncs.core_3_2 = QOpenGLVersionFunctionsFactory::get<QOpenGLFunctions_3_2_Core>(ctx);
            vaoFuncsType = Core_3_2;
            vaoFuncs.core_3_2->glGenVertexArrays(1, &vao);
        } else if (format.majorVersion() >= 3) {
            vaoFuncs.core_3_0 = QOpenGLVersionFunctionsFactory::get<QOpenGLFunctions_3_0>(ctx);
            vaoFuncsType = Core_3_0;
            vaoFuncs.core_3_0->glGenVertexArrays(1, &vao);
        } else
#endif
        if (ctx->hasExtension(QByteArrayLiteral("GL_ARB_vertex_array_object"))) {
            vaoFuncs.helper = QOpenGLVertexArrayObjectHelper::vertexArrayObjectHelperForContext(ctx);
            vaoFuncsType = ARB;
            vaoFuncs.helper->glGenVertexArrays(1, &vao);
        } else if (ctx->hasExtension(QByteArrayLiteral("GL_APPLE_vertex_array_object"))) {
            vaoFuncs.helper = QOpenGLVertexArrayObjectHelper::vertexArrayObjectHelperForContext(ctx);
            vaoFuncsType = APPLE;
            vaoFuncs.helper->glGenVertexArrays(1, &vao);
        }
    }
 
    return (vao != 0);
}
 
void QOpenGLVertexArrayObjectPrivate::destroy()
{
    Q_Q(QOpenGLVertexArrayObject);
 
    QOpenGLContext *ctx = QOpenGLContext::currentContext();
    QOpenGLContext *oldContext = nullptr;
    QSurface *oldContextSurface = nullptr;
    QScopedPointer<QOffscreenSurface> offscreenSurface;
    if (context && context != ctx) {
        oldContext = ctx;
        oldContextSurface = ctx ? ctx->surface() : nullptr;
        // Before going through the effort of creating an offscreen surface
        // check that we are on the GUI thread because otherwise many platforms
        // will not able to create that offscreen surface.
        if (QThread::currentThread() != guiThread) {
            ctx = nullptr;
        } else {
            // Cannot just make the current surface current again with another context.
            // The format may be incompatible and some platforms (iOS) may impose
            // restrictions on using a window with different contexts. Create an
            // offscreen surface (a pbuffer or a hidden window) instead to be safe.
            offscreenSurface.reset(new QOffscreenSurface);
            offscreenSurface->setFormat(context->format());
            offscreenSurface->create();
            if (context->makeCurrent(offscreenSurface.data())) {
                ctx = context;
            } else {
                qWarning("QOpenGLVertexArrayObject::destroy() failed to make VAO's context current");
                ctx = nullptr;
            }
        }
    }
 
    if (context) {
        QObject::disconnect(context, SIGNAL(aboutToBeDestroyed()), q, SLOT(_q_contextAboutToBeDestroyed()));
        context = nullptr;
    }
 
    if (vao && ctx) {
        switch (vaoFuncsType) {
#if !QT_CONFIG(opengles2)
        case Core_3_2:
            vaoFuncs.core_3_2->glDeleteVertexArrays(1, &vao);
            break;
        case Core_3_0:
            vaoFuncs.core_3_0->glDeleteVertexArrays(1, &vao);
            break;
#endif
        case ARB:
        case APPLE:
        case OES:
            vaoFuncs.helper->glDeleteVertexArrays(1, &vao);
            break;
        default:
            break;
        }
 
        vao = 0;
    }
 
    if (oldContext && oldContextSurface && oldContextSurface->surfaceHandle()) {
        if (!oldContext->makeCurrent(oldContextSurface))
            qWarning("QOpenGLVertexArrayObject::destroy() failed to restore current context");
    }
}
 
void QOpenGLVertexArrayObjectPrivate::_q_contextAboutToBeDestroyed()
{
    destroy();
}
 
void QOpenGLVertexArrayObjectPrivate::bind()
{
    switch (vaoFuncsType) {
#if !QT_CONFIG(opengles2)
    case Core_3_2:
        vaoFuncs.core_3_2->glBindVertexArray(vao);
        break;
    case Core_3_0:
        vaoFuncs.core_3_0->glBindVertexArray(vao);
        break;
#endif
    case ARB:
    case APPLE:
    case OES:
        vaoFuncs.helper->glBindVertexArray(vao);
        break;
    default:
        break;
    }
}
 
void QOpenGLVertexArrayObjectPrivate::release()
{
    switch (vaoFuncsType) {
#if !QT_CONFIG(opengles2)
    case Core_3_2:
        vaoFuncs.core_3_2->glBindVertexArray(0);
        break;
    case Core_3_0:
        vaoFuncs.core_3_0->glBindVertexArray(0);
        break;
#endif
    case ARB:
    case APPLE:
    case OES:
        vaoFuncs.helper->glBindVertexArray(0);
        break;
    default:
        break;
    }
}
 
 
QOpenGLVertexArrayObject::QOpenGLVertexArrayObject(QObject* parent)
    : QObject(*new QOpenGLVertexArrayObjectPrivate, parent)
{
}
 
QOpenGLVertexArrayObject::QOpenGLVertexArrayObject(QOpenGLVertexArrayObjectPrivate &dd)
    : QObject(dd)
{
}
 
QOpenGLVertexArrayObject::~QOpenGLVertexArrayObject()
{
    destroy();
}
 
bool QOpenGLVertexArrayObject::create()
{
    Q_D(QOpenGLVertexArrayObject);
    return d->create();
}
 
void QOpenGLVertexArrayObject::destroy()
{
    Q_D(QOpenGLVertexArrayObject);
    d->destroy();
}
 
bool QOpenGLVertexArrayObject::isCreated() const
{
    Q_D(const QOpenGLVertexArrayObject);
    return (d->vao != 0);
}
 
GLuint QOpenGLVertexArrayObject::objectId() const
{
    Q_D(const QOpenGLVertexArrayObject);
    return d->vao;
}
 
void QOpenGLVertexArrayObject::bind()
{
    Q_D(QOpenGLVertexArrayObject);
    d->bind();
}
 
void QOpenGLVertexArrayObject::release()
{
    Q_D(QOpenGLVertexArrayObject);
    d->release();
}
 
 
QT_END_NAMESPACE
 
#include "moc_qopenglvertexarrayobject.cpp"