rendergraph: use opengl node and add shaders

[m0dB]

This is a follow up for #14007

With this PR, the allshader waveformwidget and allshader waveformrenderer classes use rendergraph at the highest level: each waveformrenderXX class is derived from a rendergraph node, and all nodes are added to as children to a top node in the waveformwidget. Rendering is that done using the rendergraph engine.

At this point all allshader waveformrenderer classes are derived from a rendergraph::OpenGLNode, and the actual rendering code is still OpenGL, and not yet using the rendergraph render functionality. So effectively the change is that the paintGL functions are called through the rendergraph engine, traversing the nodes, rather than by iterating over them directly in the waveformwidget.

The subsequent PRs will derive each of the allshader waveformrenderer classes from rendergraph::GeometryNode (or of a rendergraph::Node containing a tree of GeometryNodes).

This PR also adds the rendergraph shaders, which will be needed by these PRs.

[acolombier]

Looking good, just need to make a quick manual testing.

[acolombier]

What do you think of using python instead of perl? The rationnal is, most of the tools script we have are either shell (sh, ps or bat for windows) or python, and I'm thinking it could be great to reduce the proliferation of languages.

Happy to merge it as is, and provide a follow up PR to translate into Python if you would want some help on the matter?

[m0dB]

The reason for me to do this in perl is that I can do this very quickly in perl, and in python it would take me much longer. If you feel like porting it to python, be my guest!

[Holzhaus]

I'll send you a PR

[Holzhaus]

m0dB#18

[acolombier]

How would you feel about automating the generation of the .gl script using something like this?

execute_process(
  COMMAND ./generate_shaders_gl.pl
  RESULT_VARIABLE result_generate_gl
)
if (${result_generate_gl})
  message(FATAL_ERROR "Unable to generate the GL files: ${result_generate_gl}")
endif()

Alternatively, what do you think of auto generating this in the pre-commit hooks? (Note: using Python for the script might be a requirement, but this needs to be checked)

      - id: generate-rendergraph-gl
        name: generate-rendergraph-gl
        description: "Generate GL files for rendergraph saher"
        entry: ./src/rendergraph/shaders/generate_shaders_gl.pl
        require_serial: true
        language: perl
        files: ^src/rendergraph/shaders/pattern.frag/.*\.(frag|vert)$

[m0dB]

I don't know if it is worth the effort. I can simply commit the generated shaders. If the need arises to add more shaders, we can improve on this. Also note that this is only a temporary solution: With Qt >=6.6 we can use the qsb bundles from C++ directly.

[acolombier]

As we've just updated to Ubuntu 24.04 (Qt 6.4), it may be 2 years+ before the minimum Qt version is 6.6+. I don't mind updating this in a follow up PR tho.

[m0dB]

Thanks, yes, doing this in a follow up PR would be best.

[Holzhaus]

pre-commit is the better option, as it will only run on changes, not every time you build. Also, I'm not sure that python is already a build-time dependency.

I included the pre-commit hook in m0dB#18