Class: RubyLabs::SphereLab::Vector

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

Overview

Vector

A Vector is a 3-tuple of (x,y,z) coordinates. Operators defined for vector objects (where v is a vector and a is a scalar) are:

v == v
v + v
v - v
v * a
v.add(v)     (equivalent to v += v)
v.sub(v)     (equivalent to v -= v)
v.scale(a)   (equivalent to v *= a)
v.norm

Arithmetic methods are invoked for a vector v1 when Ruby evaluates an expression of the form v1 <op> v2 where <op> is , -, or *. They create a a new vector containing the result of the operation. and - do element-wise addition or and subtraction, * is a vector-scalar multiplication.

The add, sub, and scale methods modify a vector, e.g. a call to v1.add(v2) will update v1 by adding the corresponding components in v2.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(*args) ⇒ Vector

Make a new vector with the specified x, y, and z components.



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# File 'lib/spherelab.rb', line 84

def initialize(*args)
  @x, @y, @z = args
end

Instance Attribute Details

#x ⇒ Object

Returns the value of attribute x.



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# File 'lib/spherelab.rb', line 80

def x
  @x
end

#y ⇒ Object

Returns the value of attribute y.



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# File 'lib/spherelab.rb', line 80

def y
  @y
end

#z ⇒ Object

Returns the value of attribute z.



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# File 'lib/spherelab.rb', line 80

def z
  @z
end

Instance Method Details

#*(a) ⇒ Object

Create a new vector that is the product of this vector and scalar a.



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# File 'lib/spherelab.rb', line 116

def *(a)
  Vector.new(@x * a, @y * a, @z * a)
end

#+(v) ⇒ Object

Create a new vector that is the sum of this vector and vector v.



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# File 'lib/spherelab.rb', line 104

def +(v)
  Vector.new(@x + v.x, @y + v.y, @z + v.z)
end

#-(v) ⇒ Object

Create a new vector that is the difference between this vector and vector v.



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# File 'lib/spherelab.rb', line 110

def -(v)
  Vector.new(@x - v.x, @y - v.y, @z - v.z)
end

#==(v) ⇒ Object

Compare this vector with another vector v. Two vectors are the same if all three components are the same.



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# File 'lib/spherelab.rb', line 98

def ==(v)
  return (@x == v.x) && (@y == v.y) && (@z == v.z)
end

#add(v) ⇒ Object

Add the components of vector v to this vector.



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# File 'lib/spherelab.rb', line 122

def add(v)
  @x += v.x
  @y += v.y
  @z += v.z
  self
end

#angle(v) ⇒ Object

Compute the angle between this vector and vector v. This method is only used when drawing 2D vectors, so the z dimension is ignored.



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# File 'lib/spherelab.rb', line 156

def angle(v)
  acos((@x * v.x + @y * v.y) / (norm * v.norm))
end

#coords ⇒ Object

Return a vector of three Floats corresponding to the x, y, and z components of this vector.



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# File 'lib/spherelab.rb', line 163

def coords
  [@x, @y, @z]
end

#coords=(a) ⇒ Object

Set the three components of this vector to the values in the array a, which should be an array of three Floats (it can have more values, but only the first three are used).



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# File 'lib/spherelab.rb', line 171

def coords=(a)
  @x = a[0]
  @y = a[1]
  @z = a[2]
end

#inspect ⇒ Object

Create a string that displays the x, y, and z coordinates of the vector.



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# File 'lib/spherelab.rb', line 90

def inspect
  pos = [@x,@y,@z].map { |x| sprintf "%.5g", x }
  return "(" + pos.join(",") + ")"
end

#norm ⇒ Object

Compute the magnitude of this vector, which is the Euclidean norm defined by sqrt(x**2 + y**2 + z**2)



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# File 'lib/spherelab.rb', line 149

def norm
  sqrt(@x*@x + @y*@y + @z*@z)
end

#scale(a) ⇒ Object

Multiply each component of this vector by scalar a.



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# File 'lib/spherelab.rb', line 140

def scale(a)
  @x *= a
  @y *= a
  @z *= a
end

#sub(v) ⇒ Object

Subtract the components of vector v from this vector.



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# File 'lib/spherelab.rb', line 131

def sub(v)
  @x -= v.x
  @y -= v.y
  @z -= v.z
  self
end