Joao S. O. Bueno Calligaris wrote:
On Monday 08 May 2006 10:51 pm, GSR - FR wrote:
That reminds me another parameter, velocity (or time delta, it is
related) and that airbrush had issues with high speed... anybody
knows the exact definition and use of gimp_paint_core_paint's
guint32 time (I traced to
http://developer.gimp.org/api/2.0/app/GimpPaintCore.html but says
nothing)?
I tried to fiddle with it once (implementing speed as a way to select
the frame of animated brushes), and got mostly lost myself. All I
know is that the ink tool has a different implementation that does
"time smoothing" or something to interpolate the gtk+ event time.
The ink tool uses velocity to (optionally) add pressure attenuation
according to velocity, e.g. faster strokes are thinner, which was
the most interesting interpretation of velocity according to the
#gimp resident artist.
This was particularly interesting for mouse or dumb-tablet users
without pressure-input devices to achieve organic strokes. It
was discovered that X (and thus GDK) timestamps on these events
had awful resolution, hence the timestamp filtering mechanism. I
don't think that any other brushes at the time were velocity-
sensitive (are they now?), hence the private implementation.
Regards,
--adam
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