Pokeraitis
Not specific to ryzom, but it sounds like RGBA should be noted as 4 hex numbers,
so RGBa(0, 0, 0, 0.5) should corespond to 00000080
where all four values are 0-255 (h00-hFF), 0.5 being 128 = h80.
No, it's not quite like that from what I've experienced so far. Each slot takes only a single hex number 0-f. Having written that, I have an idea for getting close. OK...this seems to work relatively well:
Pick a color using typical RGB format such as rgb(0,245,184). Divide each value by 16, rounded to the nearest integer. Convert that integer to a Hex value and use that value for Ryzom's color tag. RGB(0,245,184) becomes @{0fbf}. Not perfect but fairly close.
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Eldest, Order of the White Lotus