Hi Léo, On 2/25/20 3:15 PM, Léo Adam wrote:
Have look at the manual tests in Qt3D https://code.qt.io/cgit/qt/qt3d.git/tree/tests/manual?h=5.15Hi,I am new to Qt3D and there's a few things I was wondering how to achieve: - I need to read and write an opengl texture from C++.For example, I am rendering a scene into a texture during a first render pass, and then performing some postprocess effect before rendering that texture in a fullscreen quad during a second render pass. I would like to access that texture from C++, and can't manage to do that. I've found the classes /QTextureImageData///QTextureData///QTextureDataGenerator/, but I don't know if that's really what I'm looking for and if it is, how to use it.
- texture-updates-cpp -> C++ to GPU uploads - rendercapture* -> GPU Back buffer / FBO to C++/QML download- sharedtexture if you want to create a raw OpenGL texture and have Qt3D use it
- deferred-renderer* for rendering into FBO and reusing FBO attachement in a second pass
- I also would like to send preprocessor instructions to a shader from C++/QML and I don't know if this is possible. For example, if I want to use /#ifdef/ in a shader with a value defined in C++, I would need to send that value to the shader just like /QParameter/ do with uniforms. I've searched in the documentation and on internet, but I didn't find anything.
changing the #ifdef would trigger a whole shader recompilation , fine for prototyping, probably not for production.
You would have to modify the shader code directly, something like:
property int value: 1
ShaderProgram {
fragmentShader: "
#ifdef " + value + "
...
#else
..."
}
Any help would be highly appreciated :-) Sincerely, Léo. _______________________________________________ Interest mailing list Interest@qt-project.org https://lists.qt-project.org/listinfo/interest
-- Paul Lemire | paul.lem...@kdab.com | Senior Software Engineer KDAB (France) S.A.S., a KDAB Group company Tel: France +33 (0)4 90 84 08 53, http://www.kdab.fr KDAB - The Qt, C++ and OpenGL Experts
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