Hi Léo,
On 2/25/20 3:15 PM, Léo Adam wrote:
Hi,
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.
Have look at the manual tests in Qt3D
https://code.qt.io/cgit/qt/qt3d.git/tree/tests/manual?h=5.15
- 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
smime.p7s
Description: S/MIME Cryptographic Signature
___
Interest mailing list
Interest@qt-project.org
https://lists.qt-project.org/listinfo/interest
