qt: introduce `QSGRectangularNoiseNode` that uses proper blend factors
Depends on !6477 (merged).
Advantages:
-
ShaderEffect
seems to create a dummy texture when there is no texture provided. Although it is not sampled in the noise fragment shader, it is still waste of resources. - We want to use blend factors
(One, One)
instead of the default(One, OneMinusSrcAlpha)
of the scene graph renderer.ShaderEffect
does not allow adjusting these.
Disadvantages:
- Not as simple as using
ShaderEffect
.
Request review @chub. If the noise is still different, the cause must not be about blending.