xenobrain / ruby_vectormath Goto Github PK

Since DragonRuby 3.9, there is a built-in Vec2:

e = Vec2.new
# {}
e.class
# Vec2
Vec2.superclass
# Hash
a = MatrixFunctions.vec2(1, 2)
# {:x=>1, :y=>2}
b = MatrixFunctions.vec2(3, 4)
# {:x=>3, :y=>4}
c = a + b
# {:x=>4.0, :y=>6.0}
d = Vec2.new(1, 2)
# EXCEPTION: wrong number of arguments (given 2, expected 0..1)

if you include vectormath_2d from this library (without wrapping it in a module), it monkey-patches the built-in class which results in some odd behavior:

a = MatrixFunctions.vec2(1, 2)
b = MatrixFunctions.vec2(3, 4)
c = a + b
c.x
# 0.0
c.y
# 0.0
c[:x]
# 1
c[:y]
# 2

Some options that spring to mind:

• If this implementation is superior to the built-in one, it should be renamed to make it distinct (or wrapped in a module)
• If there is some performance reason why the built-in one uses Hashes, it would be great if this could intentionally monkey-patch the built-in Vec2 to add all of the in-place methods

Relevant part of the DR changelog:

** [Standard] The following matrix math apis have been added to Object (accessible from anywhere):
The intent of these matrix functions is to mirror GLSL matrix apis.

• vec(2|3|4): Creates a vec with the given dimension. Represented as a Hash
  with the primitive_marker set to :vec2, :vec3, or vec4.
• mat(2|3|4): Creates a mat with the given dimension. Represented as a Hash of Hashes
  with the primitive_marker set to :mat2, :mat3, :mat4 at the top level,
  and :vec(2|3|4) for each vector component.
• add: Adds matrices given to the function (returns nil if a matrix multiplication isn't valid).
• mul: Multiplies matrices given to the function. Returns nil if the matrices are incompatible.
• dot: Performs a scalar dot product for matrices given a list of matrices. Returns nil if the matrices are incompatible.
• cross: Performs a cross product for matrices given a list of matrices. Returns nil if the matrices are incompatible.
• normalize: Normalizes a vector. Returns the new normalized vector as a new Hash.
• normalize!: Normalizes a vector. Mutates the vector passed in.
• distance: Returns the distance between to vectors. Returns nil if the vectors are incompatible.
• Hash#+: Delegates to add for matrix multiplication. Returns nil if the matrices are
  incompatible or if primitive_marker isn't set on the Hash.
• Hash#*: Delegates to mul for matrix multiplication. Returns nil if the matrices are
  incompatible or if primitive_marker isn't set on the Hash.

Calling sub_from! always sets @y to 0.

   def sub_from!(vec2_lhs, vec2_rhs)
     @x = vec2_lhs.x - vec2_rhs.x
-    @y = vec2_lhs.y - vec2_lhs.y
+    @y = vec2_lhs.y - vec2_rhs.y
     self
   end