Hello.
I haven’t been able to follow this post step by step, but I’ve seen how @kofa’s creation—adapting Blender’s AgX to darktable—has delivered exceptional results. With each update, the advancements made by @kofa have left me in awe, and like many users/developers here, I appreciate the contributions to this excellent program. The possibilities of this module are vast, and thanks to the input and suggestions from @s7habo and other users testing the module, we’re witnessing a Proof of Concept (POC) gain momentum, evolving from an idea into a more solid project.
Regarding the UI design of the module—and this is just my humble opinion (I’m not a programmer)—I’d like to share an idea, which may or may not be worth considering.
The module currently has the necessary sliders to achieve detailed tone mapping, perhaps not as extensive as Filmic RGB (which can become complex due to its many functions) but closer to Sigmoid in terms of the options it provides (I’m commenting on the UI, not the module’s functionality).
I believe the module should focus on including only what’s essential to achieve its purpose without overcrowding the interface with sliders or expanding its size. For example, displaying the curve isn’t inherently bad, but in this case, the curve is purely informational, as users can’t interact with it directly like in other software—or even elsewhere in darktable, such as the tone equalizer or color equalizer. In the latter, I particularly like how nodes on the curve can be adjusted, while keeping advanced, precision controls hidden (these can be toggled via middle mouse button: “You can also adjust the color nodes using sliders, which can be shown/hidden by middle-clicking on the curve adjustment section of the module.”) Look at Tone Equalizer proposal - #9 by difrkaguilar
In this module, since the curve isn’t modified via direct interaction (only through precise sliders), hiding the curve entirely—or not displaying it at all—could result in a cleaner UI. This would better accommodate users on laptops or screens with 1920x1080px resolutions.