Cyrille Thanks for mentioning the motion blur features in gem. I've been messing about with these for a while and I thought I'd show off some pretty patching that's resulted. As always, constructive criticism is appreciated
> Date: Sat, 23 Jan 2010 01:15:09 +0000 > From: [email protected] > To: [email protected] > CC: [email protected] > Subject: Re: [PD] Drawing lines in gem with alpha fade > > James Dunn wrote: > > Thanks - it's interesting but doesn't seem to do quite what I need. Even > > with a maximum alpha value, I still want the lines to stay on full > > brightness for longer. Also, I'm drawing some fine lines and there are > > some weird artefacts like blocks appearing in the trail. Is there > > something else I could try? > > This is probably caused by the texture being 8-bit per channel, so decay > coefficients are quantized in 1/256 increments, which makes long decay > times hard to achieve (the slowest decay's coefficient is 255/256, which > isn't as close to 1.0 as you want, I guess). > > You could keep some data about the history of each line segment > (position, time created, colour, etc), and draw them all fresh each > frame - this will be much less efficient than texture feedback but you > would have more control over the fade, with the possibility to do > things like change colour (not just alpha) over time with > other-than-exponential decay curves, etc. > > Probably pd/doc/Gem/02.advanced/20.double-gemhead_vs_repeat.pd helps. > > If that gets too slow you could combine the drawing of the line segments > into one glBegin/End block at the price of some flexibility. And if > that gets too slow, there's probably something that can be done with > vertex arrays/buffers or whatever they're called (if it's even possible > in Gem - I'm not sure, but I'd like to find out!). > > > Claude > > > > > Quoth cyrille henry, on 22/01/10 21:45: > >> have a look at example 07.texture/08.MotionBlur.pd > >> all you have to do is remplace the teapot with a line that you can > >> draw or not (to make it fade out) > >> > >> Cyrille > >> > >> > >> James Dunn a écrit : > >>> I've been sending x/y values to [curve] to draw some lines in gem and > >>> the only way I've been able to get them to stay rendered is to use > >>> single buffer mode using [buffer 1( messaged to [gemwin]. > >>> > >>> Can someone suggest a better method using double buffer perhaps? I > >>> would like the lines to fade out after some seconds. I looked at > >>> pix_snap2tex and gemframebuffer but could only get one line rendered. > >>> Is this possible with the particle objects? > >>> > >>> thanks > >>> > >>> James > > -- > http://claudiusmaximus.goto10.org > > _______________________________________________ > [email protected] mailing list > UNSUBSCRIBE and account-management -> > http://lists.puredata.info/listinfo/pd-list _________________________________________________________________ We want to hear all your funny, exciting and crazy Hotmail stories. Tell us now http://clk.atdmt.com/UKM/go/195013117/direct/01/
pretty spiro.pd
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