kwin/platformsupport/scenes/opengl/backend.cpp
Vlad Zahorodnii 0ceff5fd24 Swap buffers after finishing a compositing cycle
The compositing timing algorithm assumes that glXSwapBuffers() and
eglSwapBuffers() block. While this was true long time ago with NVIDIA
drivers, nowadays, it's not the case. The NVIDIA driver queues
several buffers in advance and if the application runs out of them,
it will block. With Mesa driver, swapping buffer was never blocking.

This change makes the render backends swap buffers right after ending
a compositing cycle. This may potentially block, but it shouldn't be
an issue with modern drivers. In case it gets proven, we can move
glXSwapBuffers() and eglSwapBuffers() in a separate thread.

Note that this change breaks the compositing timing algorithm, but
it's already sort of broken with Mesa drivers.
2021-01-06 16:59:29 +00:00

94 lines
2.1 KiB
C++

/*
KWin - the KDE window manager
This file is part of the KDE project.
SPDX-FileCopyrightText: 2006 Lubos Lunak <l.lunak@kde.org>
SPDX-FileCopyrightText: 2009, 2010, 2011 Martin Gräßlin <mgraesslin@kde.org>
SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "backend.h"
#include <kwineffects.h>
#include <logging.h>
#include "screens.h"
#include <epoxy/gl.h>
namespace KWin
{
OpenGLBackend::OpenGLBackend()
: m_syncsToVBlank(false)
, m_blocksForRetrace(false)
, m_directRendering(false)
, m_haveBufferAge(false)
, m_failed(false)
{
}
OpenGLBackend::~OpenGLBackend()
{
}
void OpenGLBackend::setFailed(const QString &reason)
{
qCWarning(KWIN_OPENGL) << "Creating the OpenGL rendering failed: " << reason;
m_failed = true;
}
void OpenGLBackend::addToDamageHistory(const QRegion &region)
{
if (m_damageHistory.count() > 10)
m_damageHistory.removeLast();
m_damageHistory.prepend(region);
}
QRegion OpenGLBackend::accumulatedDamageHistory(int bufferAge) const
{
QRegion region;
// Note: An age of zero means the buffer contents are undefined
if (bufferAge > 0 && bufferAge <= m_damageHistory.count()) {
for (int i = 0; i < bufferAge - 1; i++)
region |= m_damageHistory[i];
} else {
const QSize &s = screens()->size();
region = QRegion(0, 0, s.width(), s.height());
}
return region;
}
OverlayWindow* OpenGLBackend::overlayWindow() const
{
return nullptr;
}
void OpenGLBackend::copyPixels(const QRegion &region)
{
const int height = screens()->size().height();
for (const QRect &r : region) {
const int x0 = r.x();
const int y0 = height - r.y() - r.height();
const int x1 = r.x() + r.width();
const int y1 = height - r.y();
glBlitFramebuffer(x0, y0, x1, y1, x0, y0, x1, y1, GL_COLOR_BUFFER_BIT, GL_NEAREST);
}
}
QSharedPointer<KWin::GLTexture> OpenGLBackend::textureForOutput(AbstractOutput* output) const
{
Q_UNUSED(output)
return {};
}
void OpenGLBackend::aboutToStartPainting(int screenId, const QRegion &damage)
{
Q_UNUSED(screenId)
Q_UNUSED(damage)
}
}