Work in progress

box_fluid_demo.rb

require 'toxiclibs'

#
# <p>BoxFLuid demo combining 3D physics particles with the IsoSurface class to
# create an animated mesh with a fluid behaviour. The mesh is optionally created
# within a boundary sphere, but other forms can be created using a custom
# ParticleConstraint class.</p>
#
# <p>Dependencies:</p>
# <ul>
# <li>toxiclibscore-0015 or newer package from <a href="http://toxiclibs.org">toxiclibs.org</a></li>
# <li>verletphysics-0004 or newer package from <a href="http://toxiclibs.org">toxiclibs.org</a></li>
# <li>volumeutils-0002 or newer package from <a href="http://toxiclibs.org">toxiclibs.org</a></li>
# <li>controlP5 GUI library from <a href="http://sojamo.de">sojamo.de</a></li>
# </ul>
#
# <p>Key controls:</p>
# <ul>
# <li>w : wireframe on/off</li>
# <li>c : close sides on/off</li>
# <li>p : show particles only on/off</li>
# <li>b : turn bounding sphere on/off</li>
# <li>r : reset particles</li>
# <li>s : save current mesh as OBJ & STL format</li>
# <li>- / = : decrease/increase surface threshold/tightness</li>
# </ul>
#/

#
# Copyright (c) 2009 Karsten Schmidt
#
# This demo & library is free software you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation either
# version 2.1 of the License, or (at your option) any later version.
#
# http://creativecommons.org/licenses/LGPL/2.1/
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
#
NUM_PARTICLES = 100
REST_LENGTH=183.0
DIM=100
GRID=9
VS =2.0 * DIM / GRID
SCALE=TVec3D.new(DIM,DIM,DIM).scale(2.0)
SphereConstraint = Java::ToxiPhysics3dConstraints::SphereConstraint

attr_reader :ui, :iso_threshold, :physics, :bounding_sphere, :mesh
attr_reader :surface, :show_physics, :is_wire_frame, :is_closed, :use_boundary
attr_reader :volume, :gravity, :col_amp, :num_p

def setup
  size(640, 360, P3D)
  smooth
  init_physics
  @volume=Volume::VolumetricSpaceArray.new(SCALE,GRID,GRID,GRID)
  @surface=Volume::ArrayIsoSurface.new(volume)
  @iso_threshold=1.5
  @mesh=TriangleMesh.new('fluid')
  @show_physics=false
  @is_wire_frame=false
  @is_closed=true
  @use_boundary=false
  @col_amp=TVec3D.new(200, 100, 100)
  text_font(create_font('SansSerif', 12))
end

def draw  
  background(224)
  hint(DISABLE_DEPTH_TEST)
  fill(0)
  text(format('faces: %d', mesh.getNumFaces), 20, 290)
  text(format('vertices: %d', mesh.getNumVertices), 20, 305)
  text(format('particles: %d', physics.particles.size), 20, 320)
  text(format('springs: %d', physics.springs.size), 20, 335)
  text(format('fps: %d', frame_rate), 20, 350)
  hint(ENABLE_DEPTH_TEST)
  update_particles
  compute_volume
  translate(width * 0.5, height * 0.5, 0)
  rotate_x(mouse_y * 0.01)
  rotate_y(mouse_x * 0.01)
  no_fill
  stroke(255, 192)
  stroke_weight(1)
  box(physics.get_world_bounds.get_extent.x * 2)
  if show_physics
    stroke_weight(4)
    stroke(0)
    physics.particles.each do |p|
      col = p.add(col_amp).scale_self(1.0)
      stroke(col.x, col.y, col.z)
      point(p.x, p.y, p.z)
    end
  else
    ambient_light(216, 216, 216)
    directional_light(255, 255, 255, 0, 1, 0)
    directional_light(96, 96, 96, 1, 1, -1)
    if is_wire_frame
      stroke(255)
      no_fill
    else
      no_stroke
      fill(224,0,51)
    end
    begin_shape(TRIANGLES)
    is_wire_frame ? draw_wire_mesh : draw_filled_mesh
    end_shape
  end
end


def keyPressed
  case key
  when 'r'
    init_physics
  when 'w'
    @is_wire_frame=!is_wire_frame
  when 'p'
    @show_physics=!show_physics
  when 'c'
    @is_closed=!is_closed
  when 'b'
    toggle_boundary
  when '-', '_'
    @iso_threshold -= 0.001
  when '=', '+'
    @iso_threshold += 0.001
  when 's'
    mesh.saveAsOBJ(sketchPath(format('%s.obj', mesh.name)))
    mesh.saveAsSTL(sketchPath(format('%s.stl', mesh.name)))
  end
end

def toggle_boundary
  @use_boundary = !use_boundary
  init_physics
end

def compute_volume
  cell_size = DIM.to_f * 2 / GRID
  pos = TVec3D.new
  offset = physics.get_world_bounds.get_min
  volume_data = volume.get_data 
  index = 0
  GRID.times do |z| 
    pos.set_z(z * cell_size + offset.z)
    GRID.times do |y|
      pos.set_y(y * cell_size + offset.y)
      GRID.times do |x|
        pos.set_x(x * cell_size + offset.x)
        val=0
        physics.particles.each do |p|          
          mag = pos.distanceToSquared(p) + 0.00001
          val += 1.0 / mag
        end
        volume_data[index] = val
        index += 1
      end
    end
  end
  volume.close_sides if is_closed
  surface.reset
  surface.compute_surface_mesh(mesh, iso_threshold * 0.001)
end

def draw_filled_mesh
  mesh.compute_vertex_normals
  mesh.faces.each do |f|
    col = f.a.add(col_amp).scale_self(1.0)
    fill(col.x,col.y,col.z)
    normal_v(f.a.normal)
    vertex_v(f.a)
    col=f.b.add(col_amp).scale_self(1.0)
    fill(col.x,col.y,col.z)
    normal_v(f.b.normal)
    vertex_v(f.b)
    col=f.c.add(col_amp).scale_self(1.0)
    fill(col.x,col.y,col.z)
    normal_v(f.c.normal)
    vertex_v(f.c)
  end
end

def draw_wire_mesh
  no_fill
  mesh.faces.each do |f|
    col=f.a.add(col_amp).scale_self(1.0)
    stroke(col.x,col.y,col.z)
    vertex_v(f.a)
    col=f.b.add(col_amp).scale_self(1.0)
    stroke(col.x,col.y,col.z)
    vertex_v(f.b)
    col=f.c.add(col_amp).scale_self(1.0)
    stroke(col.x,col.y,col.z)
    vertex_v(f.c)
  end
end

def normal_v(v)
  normal(v.x, v.y, v.z)
end

def vertex_v(v)
  vertex(v.x, v.y, v.z)
end

def init_physics
  @physics=Physics::VerletPhysics3D.new
  physics.set_world_bounds(AABB.new(TVec3D.new, TVec3D.new(DIM,DIM,DIM)))
  unless surface.nil? 
    surface.reset
    mesh.clear
  end
  @bounding_sphere=SphereConstraint.new(Toxi::Sphere.new(TVec3D.new,DIM),SphereConstraint::INSIDE)
  @gravity=Physics::GravityBehavior3D.new(TVec3D.new(0, 0.6, 0))
  physics.add_behavior(gravity)
end

def update_particles
  grav = TVec3D::Y_AXIS.copy
  grav.rotate_x(mouse_y * 0.01)
  grav.rotate_y(mouse_x * 0.01)
  gravity.setForce(grav.scale_self(2))
  @num_p = physics.particles.size
  if (rand < 0.8 && num_p < NUM_PARTICLES)
    p = Physics::VerletParticle3D.new(TVec3D.new(random(-1,1)*10), -DIM, random(-1,1)*10)))
    p.add_constraint(bounding_sphere) if use_boundary
    physics.add_particle(p)
  end
  if (num_p > 5) && (physics.springs.size < 700)
    30.times do
      if rand < 0.04
        q = physics.particles.get(rand(0...num_p))
        r = q
        Kernel.loop do
          break unless q == r
          r = physics.particles.get(rand(0...num_p))
          physics.add_spring(Physics::VerletSpring3D.new(q, r, REST_LENGTH, 0.0001))          
        end 
      end
    end
  end
  len = num_p.to_f / NUM_PARTICLES * REST_LENGTH
  physics.springs.map { |s| s.set_rest_length(rand(0.9..1.1) * len) }
  physics.update
end