//! Initialize the frame buffer objects.
void initFBOs()
{
invariant();
Q_ASSERT_X(useFBO(), Q_FUNC_INFO, "We're not using FBO");
if (NULL == backBuffer)
{
Q_ASSERT_X(NULL == frontBuffer, Q_FUNC_INFO,
"frontBuffer is not null even though backBuffer is");
// If non-power-of-two textures are supported,
// FBOs must have power of two size large enough to fit the viewport.
const QSize bufferSize = nonPowerOfTwoTexturesSupported
? StelUtils::smallestPowerOfTwoSizeGreaterOrEqualTo(viewportSize)
: viewportSize;
// We want a depth and stencil buffer attached to our FBO if possible.
const QGLFramebufferObject::Attachment attachment =
QGLFramebufferObject::CombinedDepthStencil;
backBuffer = new QGLFramebufferObject(bufferSize, attachment);
frontBuffer = new QGLFramebufferObject(bufferSize, attachment);
Q_ASSERT_X(backBuffer->isValid() && frontBuffer->isValid(),
Q_FUNC_INFO, "Framebuffer objects failed to initialize");
}
invariant();
}
QGLFramebufferObject *QGLFramebufferObjectPool::acquire(const QSize &requestSize, const QGLFramebufferObjectFormat &requestFormat, bool strictSize)
{
QGLFramebufferObject *chosen = 0;
QGLFramebufferObject *candidate = 0;
for (int i = 0; !chosen && i < m_fbos.size(); ++i) {
QGLFramebufferObject *fbo = m_fbos.at(i);
if (strictSize) {
if (fbo->size() == requestSize && fbo->format() == requestFormat) {
chosen = fbo;
break;
} else {
continue;
}
}
if (fbo->format() == requestFormat) {
// choose the fbo with a matching format and the closest size
if (!candidate || areaDiff(requestSize, candidate) > areaDiff(requestSize, fbo))
candidate = fbo;
}
if (candidate) {
m_fbos.removeOne(candidate);
const QSize fboSize = candidate->size();
QSize sz = fboSize;
if (sz.width() < requestSize.width())
sz.setWidth(qMax(requestSize.width(), qRound(sz.width() * 1.5)));
if (sz.height() < requestSize.height())
sz.setHeight(qMax(requestSize.height(), qRound(sz.height() * 1.5)));
// wasting too much space?
if (sz.width() * sz.height() > requestSize.width() * requestSize.height() * 4)
sz = requestSize;
if (sz != fboSize) {
delete candidate;
candidate = new QGLFramebufferObject(maybeRoundToNextPowerOfTwo(sz), requestFormat);
}
chosen = candidate;
}
}
if (!chosen) {
if (strictSize)
chosen = new QGLFramebufferObject(requestSize, requestFormat);
else
chosen = new QGLFramebufferObject(maybeRoundToNextPowerOfTwo(requestSize), requestFormat);
}
if (!chosen->isValid()) {
delete chosen;
chosen = 0;
}
return chosen;
}