Class: Simple3d::Mesh

Inherits:
Object
  • Object
show all
Defined in:
lib/simple3d/mesh.rb

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(options = {}) ⇒ Mesh

Returns a new instance of Mesh.



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# File 'lib/simple3d/mesh.rb', line 6

def initialize options = {}
  @indices = options[:indices]
  if @indices.nil? && options[:vertices]
    options[:vertices].each_slice(3) do |points|
      add_face points, options[:reuse_existing_points]
    end
  else
    @vertices = options[:vertices]
  end

  @indices ||= []
  @vertices ||= []
end

Instance Attribute Details

#indices ⇒ Object

Returns the value of attribute indices.



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# File 'lib/simple3d/mesh.rb', line 3

def indices
  @indices
end

#vertices ⇒ Object

Returns the value of attribute vertices.



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# File 'lib/simple3d/mesh.rb', line 4

def vertices
  @vertices
end

Class Method Details

.from_file(filename) ⇒ Object 



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# File 'lib/simple3d/mesh.rb', line 20

def self.from_file filename
  m = self.new

  w = Wavefront::File.new filename
  w.compute_vertex_buffer.each_slice(3) do |slice|
    m.add_face slice.map{|wv| wv.position.to_a + [wv.tex.x, wv.tex.y] + wv.normal.to_a }
  end

  m
end

.unit_cube ⇒ Object 



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# File 'lib/simple3d/mesh.rb', line 178

def self.unit_cube
  cube = self.new
  cube.add_face [[1, -1, -1], [1, -1, 1], [-1, -1, 1], [-1, -1, -1]]
  cube.add_face [[1, 1, -1], [-1, 1, -1], [-1, 1, 1], [1, 1, 1]]
  cube.add_face [[1, -1, -1], [1, 1, -1], [1, 1, 1], [1, -1, 1]]
  cube.add_face [[1, -1, 1], [1, 1, 1], [-1, 1, 1], [-1, -1, 1]]
  cube.add_face [[-1, -1, 1], [-1, 1, 1], [-1, 1, -1], [-1, -1, -1]]
  cube.add_face [[1, 1, -1], [1, -1, -1], [-1, -1, -1], [-1, 1, -1]]
  cube
end

Instance Method Details

#add_face(points, reuse_existing_points = true) ⇒ Object 



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# File 'lib/simple3d/mesh.rb', line 31

def add_face points, reuse_existing_points = true
  if points.size > 4
    raise "faces with more than four points currently not supported"
  elsif points.size == 4
    add_face [points[0], points[1], points[3]]
    add_face [points[3], points[1], points[2]]
  else
    points.each do |pt|
      pt = Vertex.new *pt if pt.kind_of? Array
      similar_vertex_index = if reuse_existing_points
                               find_similar_vertex pt
                             else
                               nil
                             end
      if similar_vertex_index
        @indices << similar_vertex_index
      else
        @vertices << pt
        @indices << @vertices.size - 1
      end
    end
  end
end

#calculate_tangents! ⇒ Object 



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# File 'lib/simple3d/mesh.rb', line 116

def calculate_tangents!
  tan1 = Array.new vertices.size
  tan2 = Array.new vertices.size
  for i in 0..vertices.size-1
    tan1[i] = Geo3d::Vector.new
    tan2[i] = Geo3d::Vector.new
  end

  for a in 0..num_triangles-1
    i1, i2, i3 = indices_for_triangle a

    v1 = vertices[i1].position
    v2 = vertices[i2].position
    v3 = vertices[i3].position

    w1 = vertices[i1].texcoord
    w2 = vertices[i2].texcoord
    w3 = vertices[i3].texcoord

    x1 = v2.x - v1.x
    x2 = v3.x - v1.x
    y1 = v2.y - v1.y
    y2 = v3.y - v1.y
    z1 = v2.z - v1.z
    z2 = v3.z - v1.z

    s1 = w2.x - w1.x
    s2 = w3.x - w1.x
    t1 = w2.y - w1.y
    t2 = w3.y - w1.y

    r = 1.0 / (s1 * t2 - s2 * t1)
    sdir = Geo3d::Vector.new (t2 * x1 - t1 * x2) * r, (t2 * y1 - t1 * y2) * r, (t2 * z1 - t1 * z2) * r
    tdir = Geo3d::Vector.new (s1 * x2 - s2 * x1) * r, (s1 * y2 - s2 * y1) * r, (s1 * z2 - s2 * z1) * r

    tan1[i1] += sdir
    tan1[i2] += sdir
    tan1[i3] += sdir

    tan2[i1] += tdir
    tan2[i2] += tdir
    tan2[i3] += tdir
  end

  for a in 0..vertices.size-1

    n = vertices[a].normal
    t = tan1[a]

    puts "n is #{n.inspect}"
    puts "t is #{t.inspect}"

    # Gram-Schmidt orthogonalize
    vertices[a].tangent = (t - n * n.dot(t)).normalize

    # Calculate handedness
    # tangent(a).w = (Dot(Cross(n, t), tan2[a]) < 0.0F) ? -1.0F : 1.0F;
    vertices[a].tangent.w = n.cross(t).dot(tan2[a]) < 0.0 ? -1.0 : 1.0
  end
end

#collapse_similar_vertices! ⇒ Object 



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# File 'lib/simple3d/mesh.rb', line 63

def collapse_similar_vertices!
  faces = indices.each_slice(3)

  old_vertices = @vertices
  old_indices = @indices
  @vertices = @indices = nil


end

#find_similar_vertex(v) ⇒ Object 



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# File 'lib/simple3d/mesh.rb', line 56

def find_similar_vertex v
  vertices.each_with_index do |vt, i|
    return i if vt.position == v.position && vt.texcoord == v.texcoord
  end
  nil
end

#indices_for_triangle(i) ⇒ Object 



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# File 'lib/simple3d/mesh.rb', line 83

def indices_for_triangle i
  [indices[i*3], indices[i*3+1], indices[i*3+2]]
end

#num_triangles ⇒ Object 



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# File 'lib/simple3d/mesh.rb', line 73

def num_triangles
  indices.size / 3
end

#renderable_vertices ⇒ Object 



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# File 'lib/simple3d/mesh.rb', line 77

def renderable_vertices
  indices.map do |i|
    vertices[i]
  end
end

#smooth_normals! ⇒ Object 



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# File 'lib/simple3d/mesh.rb', line 96

def smooth_normals!
  indices_to_face_normals = Array.new vertices.size
  for i in 0..vertices.size-1
    indices_to_face_normals[i] = []
  end

  for a in 0..num_triangles-1
    tri = triangle a
    indices_for_triangle(a).each do |vertex_index|
      face_normal = tri.normal
      indices_to_face_normals[vertex_index] << face_normal
    end
  end

  for i in 0..vertices.size-1
    face_normals = indices_to_face_normals[i]
    vertices[i].normal = face_normals.inject(:+).normalize
  end
end

#triangle(i) ⇒ Object 



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# File 'lib/simple3d/mesh.rb', line 91

def triangle i
  Geo3d::Triangle.new *(vertices_for_triangle(i).map(&:position))
end

#vertices_for_triangle(i) ⇒ Object 



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# File 'lib/simple3d/mesh.rb', line 87

def vertices_for_triangle i
  indices_for_triangle(i).map { |index| vertices[index] }
end