I found a script that calculates 3D models and combines identical vertices. It has the following logic, where according to my understanding, vertices are hash maps of vertex class:
unless vertices.key?(vertex)
new_vertices << vertex
vertices[ vertex ] = @vertex_index
@vertex_index += 1
end
If we find a vertex
that is unique, we add it to the new_vertices
array.
I'd like to modify this so that the key for the hash map is a combination of a vertex and a material (both are classes from Sketchup, which is the software this script runs in). What is the best way to do this so that each key is a combination of two classes instead of one? Some sort of duple or class holding both the vertex and the material? Is that supported by a hash map?
In Ruby one might use whatever as hash key:
hash = {
42 => "an integer",
[42, "forty two"] => "an array",
Class => "a class"
}
#⇒ {42=>"an integer", [42, "forty two"]=>"an array", Class=>"a class"}
hash[[42, "forty two"]]
#⇒ "an array"
That said, in your case you might use an array [vertex, material]
as a key:
unless vertices.key?([vertex, material])
new_vertices_and_materials << [vertex, material]
vertices[[vertex, material]] = @vertex_index
@vertex_index += 1
end
The more rubyish approach would be to call Enumerable#uniq
on the input and do:
input = [ # example input data
[:vertex1, :material1],
[:vertex2, :material1],
[:vertex2, :material1],
[:vertex2, :material2],
[:vertex2, :material2]
]
new_vertices_and_materials = input.uniq
vertices_and_materials_with_index =
new_vertices_and_materials.
zip(1..new_vertices_and_materials.size).
to_h
#⇒ {[:vertex1, :material1]=>1,
# [:vertex2, :material1]=>2,
# [:vertex2, :material2]=>3}