beginNativePainting() with QPainter's shader (for transformation and opacity purpose)

[diro]

Ok but what happens if you don't use beginNativePainting() and just start making gl calls?

Oh, I got you! I have trace into the beginNativePainting() function, and it will call glUseProgram(0) to unload the shader program.
But I have two questions about don't use beginNativePainting() before gl calls:
1.Will it cause any side-effect? If not, why Qt design this function?
2.Because I use shader program, too. Could we have two program at the same time?

Anyway, really thanks for your suggestion :-)

[wysota]

1.Will it cause any side-effect?

I don't know, make an example and find it out on your own. I don't even know if it works at all.

[diro]

I don't know, make an example and find it out on your own. I don't even know if it works at all.

After some testing..
1.Will it cause any side-effect? If not, why Qt design this function?
Not sure, but the projection seems wrong, the elements didn't draw in the position I wanted.

2.Because I use shader program, too. Could we have two program at the same time?
Yes, I still can use my own shader program.

Finally, I give up this way and solve this problem by my own transformation matrix.

[diro]

I think I have to apology first, after many study and experiments, I got a new conclusion now.
For Qt painting framework, after calling the beginNativePainting(), the following gl commands will be affected by the shaders constructed by Qt(all transformation of coz)
So, you don't have to do anything, and all the elements drawn by gl commands will also be rotate, flip and so on.

The code I made in previous edition, I use some custom projection in openGL, so it looks like the previous shaders is not enabled, it is a wrong concept.