[Solved] Simplest Vertex/Fragment Shaders using QGLWidget Derivation
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I have spoken to sroedal (Qt OpenGL dude) on irc this afternoon and he is committing a patch that is very similar to what I wrote yesterday afternoon. It allows for proper parsing of OpenGL extensions when using the Core profile. It should hopefully hit Qt master branch on gitorious within a day or so.
I'll try applying it locally tonight and see if QGLShader then starts working or if further changes are needed to make it realise that shaders are supported.
I also asked about having Qt resolve the Core profile entry points and the response was thet using GLEW is the current advice - which is what we had been doing anyway. I still think it would be nice that if we ask Qt for a OpenGL 3.2 Core profile context that it then resolves the function pointers for the Core profile entry points for us without having to use GLEW. But that is another problem I guess.
I'll keep you updated.
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Your posted example with fixed function works fine. I'll try using the entire shader pipeline.
It's normally slow going for me during the week. Weekends are my most productive time for these projects.
By "entire shader pipeline" I mean vert,geom, tess control, tess eval, frag.
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Cool. I'll look forward to seeing your example. I have not used the tesselation shaders yet so I would be keen to see a nice little example. I probably won't get back to this until the weekend either but I'll keep an eye out for that patch hitting Qt master.
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No worries, real life happens - especially when nice weather lands ;-)
I have just checked and the patch to Qt master that I mentioned earlier has no been applied. So now shaders should work even if you select the Core profile.
The main part of the patch is in src/opengl/qgl.cpp in the helper class QGLExtensionMatcher found "here":https://qt.gitorious.org/qt/qt/blobs/master/src/opengl/qgl.cpp#line5373.
The corresponding commit message was:
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commit 2f59eaeee1fbe33d07b0e7d0747afd8658df95ac
Author: Samuel R<C3><B8>dal sroedal@trolltech.com
Date: Wed May 26 16:39:02 2010 +0200Made extension resolving work with Core profile. The Core profile was introduced in OpenGL 3.2 and if chosen removes all deprecated functionality from the OpenGL API. In the Core profile glGetString(GL_EXTENSIONS) is unsupported, so instead we need to use glGetStringi(GL_EXTENSIONS, index) together with glGetIntegerv(GL_NUM_EXTENSIONS). Also optimized the QGLExtensionMatcher to not have to recompute the split positions all the time. Preliminary support to prevent non-core-functions to be called in the GL 2 engine has also been added. Reviewed-by: Kim@
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If you are trying to build a checkout from gitorious you need to have perl installed. The reason is that the configure script calls a perl script called syncqt which is used to create the camelcase forwarding headers that allow you to do this:
@#include <QCoreApplication>@
These headers are generated to simply contain something like
@#include "../include/qtcore/qcoreapplication.h"@
I fell for this same problem too on windows. On linux it just works since perl is nearly always already available.
Edit: fixed typo.
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Sorry to bump an old thread but I've just written a related "wiki article":http://developer.qt.nokia.com/wiki/How_to_use_OpenGL_Core_Profile_with_Qt on this topic that shows how to use the OpenGL Core profile with Qt using some very simple shaders and a single triangle.
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moved to new "thread":http://developer.qt.nokia.com/forums/viewthread/11031/