Hmmm...  It looks like the last two bytes were stripped from the MPEG
file.  That's what I get for trying to hack a newsreader that does not
support posting of binary attachments.  ;-)  But I hope that most of
you will be able to play the animation without problems.

Although this will not be very useful until I release the source code
of my particle system, here is an excerpt from the scene file that I
used to generate the animation.  I am posting the following lines of
code in order to explain what I mean by a procedural API (see my
message in p.a-v): the main scene file calls several macros that
perform some actions on the particles.  Some of these macros can call
other user-defined macros, for example the macro pps_draw_particles()
calls the user-defined macro pps_user_draw_particle() several times.
Although this is not shown here, the macro pps_bounce() calls the
user-defined macro pps_user_hit_trigger() when a particle hits
something.  This is what allows me to trigger a splash or some sparks
using a second and third particle system.

  /* ... */
  #declare pps_target_time = 8 * clock;
  #declare pps_time_step = 0.01;

  #if (clock = 0)
    #declare pps_current_time = 0.0;
    // [...] some stuff to create the boxes (particles + springs)
  #else
    pps_load_from_file ("springbox_state.txt")
  #end
  
  // this defines the environment: this is a CSG union on which the particles
  // will bounce (one checkered plane and several spheres and cylinders)
  #declare bounce_obj = union {
    plane { y, 0
      pigment { checker color rgb 0.2 color rgb 1 }
    }
    union {
      // [...] several spheres and cylinders
    }
  }

  // run the particle system simulation
  #while (pps_iterate ())
    pps_gravity (PPS_DEFAULT_GRAVITY)
    pps_activate_springs ()
    pps_bounce (bounce_obj, 0.95, 0.07, 0)
    pps_move (0)
  #end
  pps_save_to_file ("springbox_state.txt")

  #macro pps_user_draw_particle (index, p_pos, p_size, p_velocity, p_orient, p_color,
age)
    sphere { p_pos, p_size }
  #end
  union {
    pps_draw_particles ()
    texture { T_Chrome_5D }
  }

  #macro pps_user_draw_spring (index, s_particle1, s_particle2, s_pos1, s_pos2,
s_size, s_color)
    // [...] a bit too long to post here
  #end
  union {
    pps_draw_springs ()
  }
  /* ... */

The other two particle systems (splash and sparks) use the same
structure as above, with slightly different actions in the main loop
of the simulation.  For example, here is what I used for the sparks
(of course, I redefine pps_user_draw_particle() for the sparks):

  #while (pps_iterate ())
    pps_kill_old (sparks_max_age)
    pps_gravity (PPS_DEFAULT_GRAVITY)
    pps_viscous_drag (0.9, 0, 1e9)
    pps_bounce (bounce_obj, 0.7, 0.05, 0)
    pps_move (0)
  #end
  pps_save_to_file ("sparks_state.txt")

By the way, all macros are prefixed with "pps_", for "POV Particle
System" because when I started this project a long time ago I was not
aware of other efforts to create particle systems for POV-Ray.  I am
wondering if I should rename this now that several of them are in
development...  Comments are welcome (but maybe you should post your
comments in povray.advanced-users, which is more appropriate for
discussing this kind of comments).


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

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