On Fri, 07 Jun 2002 14:33:08 +0200, Greg M. Johnson wrote:
> I'm usually the first to whine about exotic formats, but I saw this one
> with no probs.

Well, the format is not exotic (just standard MPEG created with
mpeg_encode) but the problem occured while posting the message.  Since
I cannot use my home PC for the moment (hard disk crash), I am using
another PC on which the newsreader does not support posting of binary
attachments (Pan is very nice for reading, but not for posting).  So I
had to create the mime multipart message by hand and do the base64
encoding of the file.  Apparently I lost the last 2 bytes while doing
the conversion.  That's why I was a bit worried, but apparently most
MPEG players are very tolerant and they play the animation without
problems.

> Cool!
> So what are the sparks?
 
The sparks are made with a bunch of particles that are moved by my
particle system.  Each of these particles is drawn as a sphere
containing emitting and absorbing media.  Nothing very exotic.  To
be more specific, here is exactly what these sparks are:

// definition of the sparks
#macro pps_user_draw_particle (index, p_pos, p_size, p_velocity,
                               p_orient, p_color, age)
  #local age_ratio = 1 - age / sparks_max_age;
  sphere { <0, 0, 0>, 1
    hollow on
    texture { pigment { rgbt 1 } }
    interior {
      media {
        intervals 1
        samples 5, 10
        method 3
        emission <1, 0.9, 0.6> * 10 * (0.5 + age_ratio)
        absorption <0, 0.1, 0.4> * 10 * (0.3 + age_ratio)
        density { spherical }
      }
    }
    scale 0.03 * sqrt (age_ratio)
    translate p_pos
  }
#end
// include all sparks in the scene
pps_draw_particles ()


-- 
http://www.gamers.org/~quinet/

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