I need to make some tests to confirm, but since the struct does not have alpha, it’s not clear for us if the alpha on the vec4 will use the default value currently set on the material/material instance, or if it will be overriden by 0.0 or 1.0 when using with verse.
I had problems in the past due to transparency and other color manipulation math (like using alpha channel for extra data not necessarely being transparency), and was confusing to understand what was wrong until I migrated to scalars and everything worked fine.
I would need to make a testing environment to try understanding what happened, if was due to some overriden value, a wrong default in material that I forgot or something else, then I can make a proper bug report related to it if needed.
But thanks for talking about the design behind, it explains a lot! Also having a color_alpha, even with it being just for parameters without the math operations, would be a huge benefit already! (Maybe some conversion such as (Color:color).AddAlpha(Alpha:float):color_alpha would be already enough for most use cases?)