Class: Topolys::Transformation

Inherits:
Object
  • Object
show all
Defined in:
lib/topolys/transformation.rb

Overview

Transformations can be applied to Geometry. Ported from OpenStudio Transformation library.

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(matrix = Matrix.identity(4)) ⇒ Transformation

Initializes an Transformation object

Parameters:

  • matrix (Matrix) (defaults to: Matrix.identity(4)) —

    A 4x4 matrix, defaults to identity



22
23
24
25
 
# File 'lib/topolys/transformation.rb', line 22

def initialize(matrix=Matrix.identity(4))
  raise "Incorrect argument for Transformation, expected Matrix but got #{matrix.class}" unless matrix.is_a?(Matrix)
  @matrix = matrix
end

Instance Attribute Details

#matrix ⇒ Matrix (readonly)

Returns internal 4x4 matrix.

Returns:

  • (Matrix) —

    internal 4x4 matrix



16
17
18
 
# File 'lib/topolys/transformation.rb', line 16

def matrix
  @matrix
end

Class Method Details

.rotation(axis, radians) ⇒ Object

Initializes a rotation about origin defined by axis and angle (radians)



42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
 
# File 'lib/topolys/transformation.rb', line 42

def Transformation.rotation(axis, radians)
  return nil if !axis.is_a?(Vector3D)
  return nil if !radians.is_a?(Numeric)
  return nil if (axis.magnitude < Float::EPSILON)
  normal = axis
  normal.normalize!
  
  # Rodrigues' rotation formula / Rotation matrix from Euler axis/angle
  # I*cos(radians) + I*(1-cos(radians))*axis*axis^T + Q*sin(radians)
  # Q = [0, -axis[2], axis[1]; axis[2], 0, -axis[0]; -axis[1], axis[0], 0]
  p = normal.outer_product(normal)
  i = Matrix.identity(3)
  q = Matrix.zero(3)
  q[0,1] = -normal.z
  q[0,2] =  normal.y
  q[1,0] =  normal.z
  q[1,2] = -normal.x
  q[2,0] = -normal.y
  q[2,1] =  normal.x

  # rotation matrix
  r = i*Math.cos(radians) + (1-Math.cos(radians))*p + q*Math.sin(radians)

  matrix = Matrix.identity(4)
  matrix[0,0] = r[0,0]
  matrix[0,1] = r[0,1]
  matrix[0,2] = r[0,2]
  matrix[1,0] = r[1,0]
  matrix[1,1] = r[1,1]
  matrix[1,2] = r[1,2]
  matrix[2,0] = r[2,0]
  matrix[2,1] = r[2,1]
  matrix[2,2] = r[2,2]
  
  return Transformation.new(matrix)
end

.translation(translation) ⇒ Object

translation along vector



28
29
30
31
32
33
34
35
36
37
 
# File 'lib/topolys/transformation.rb', line 28

def Transformation.translation(translation)
  return nil if !translation.is_a?(Vector3D)
  
  matrix = Matrix.identity(4)
  matrix[0,3] = translation.x
  matrix[1,3] = translation.y
  matrix[2,3] = translation.z      
  
  return Transformation.new(matrix)
end

Instance Method Details

#*(obj) ⇒ Obj

Multiplies a Transformation by geometry class

Parameters:

  • obj (Obj) —

    A geometry object

Returns:

  • (Obj) —

    Returns a new, transformed object - nil if not a geometry object



85
86
87
88
89
90
91
92
93
94
95
96
 
# File 'lib/topolys/transformation.rb', line 85

def *(obj)
  if obj.is_a?(Point3D)
    return mult_point(obj)
  elsif obj.is_a?(Vector3D)
    return mult_vector(obj)
  elsif obj.is_a?(Array)
    return mult_array(obj)
  elsif obj.is_a?(Transformation)
    return mult_transformation(obj)
  end
  return nil
end