SetAPen(RastPort*, UBYTE);

[Piru]

If you're targetting OS4:

IGraphics->SetRPAttrs( rastport, RPATTR_APenColor, 0xRRGGBB, TAG_DONE );

And if you were targetting AROS/MorphOS you would use:

SetRPAttrs( rastport, RPTAG_FgColor, 0xRRGGBB, TAG_DONE );

At least MorphOS defaults to 3.x pens though, so before using truecolor rendering you should call SetRPAttrs( rastport, RPTAG_PenMode, FALSE, TAG_DONE );. That tells MorphOS that you really want to render by using RGB rather than pens. I don't remember if AROS had such "pen mode" default or not.

Anyway, if AROS graphicslibrary would be backported you'd get the RPTAG_FgColor and RPTAG_BgColor similar to AROS/MorphOS.

Here's some example code I wrote some time ago: http://www.sintonen.fi/src/misc/truecolortest.c

[Piru]

@Piru
There is no "mode" on OS4, or at least the mode is transparent. If you set "APenColor" APen is an RGB colour value. If you then use SetAPen(), its a pen again.

Well I hope there at least is some way to get and set the mode somehow? Else it'd be a bit messy to write library code that does some rendering using specific mode while restoring the old mode afterwards.