From 3e14de57df79ef0208e1356e8cffde37b573c00d Mon Sep 17 00:00:00 2001
From: Miikka Heikkinen <miikka.heikkinen@theqtcompany.com>
Date: Wed, 20 May 2015 12:58:21 +0300
Subject: [PATCH] Actual fix for "shaking" bug that occurred in some GPUs
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The first FBO we create gets corrupted by something outside
Canvas3D in some cases. E.g. changing the text in an completely unrelated
Text element may corrupt Canvas3D FBOs. This only happens with some GPU
drivers, likely due to a bug in the drivers themselves. To work around
the issue, the first FBO we create is a dummy that we delete once the
real FBOs are done.
Change-Id: Ie8c2a0ec3899c3eb22e4de8809c3b41607cc83c3
Task-number: QTBUG-46101
Reviewed-by: Pasi Keränen <pasi.keranen@digia.com>
---
src/imports/qtcanvas3d/canvas3d.cpp | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/src/imports/qtcanvas3d/canvas3d.cpp b/src/imports/qtcanvas3d/canvas3d.cpp
index c84bc18..439fa50 100644
--- a/src/imports/qtcanvas3d/canvas3d.cpp
+++ b/src/imports/qtcanvas3d/canvas3d.cpp
@@ -537,6 +537,15 @@ void Canvas::createFBOs()
QOpenGLFramebufferObject *renderFbo = m_renderFbo;
QOpenGLFramebufferObject *antialiasFbo = m_antialiasFbo;
+ QOpenGLFramebufferObject *dummyFbo = 0;
+ if (!m_renderFbo) {
+ // Create a dummy FBO to work around a weird GPU driver bug on some platforms that
+ // causes the first FBO created to get corrupted in some cases.
+ dummyFbo = new QOpenGLFramebufferObject(m_fboSize.width(),
+ m_fboSize.height(),
+ m_fboFormat);
+ }
+
// Create FBOs
qCDebug(canvas3drendering).nospace() << "Canvas3D::" << __FUNCTION__
<< " Creating front and back FBO's with"
@@ -590,6 +599,9 @@ void Canvas::createFBOs()
bindCurrentRenderTarget();
emitNeedRender();
}
+
+ // Get rid of the dummy FBO, it has served its purpose
+ delete dummyFbo;
}
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