Hello, I have some geometry data modelling with type Triangle [3]*Vertex (The exact definition of Vertex is unimportant here, but I'd like to avoid adding more fields inside Vertex if possible.)
Then I'd like to use a triplet of vertices as the entry point of a map containing more data like color, texture, etc.: var mesh map[Triangle]Data When I traverse a big list of Vertices (following edges) to construct the list of all Triangles and their Data, it's important that I don't recreate Data for triangles that have already been visited, even if triplet is in a different order: A B C A C B B A C B C A C A B C B A ... are all the same triangle in my specific modelling. To achieve this, I consider normalizing the triplet so that all keys of the map verify A *<* B *<* C for some arbitrary definition of *<* . This ensures that I can detect any Triangle already present as key in the map, regardless the order of its Vertex pointers. Unfortunately for this approach, direct pointer arithmetic doesn't exist in go: I can test individual Vertex pointers for equality with ==, but not for ordering with < or sort.Slice or sort.Sort. I could "print a numerical string representation" of each Vertex and use the strings as keys, but this looks costly and I'm not sure about this way being reliable. I could try package unsafe to convert pointers to uintptr, but this looks unsafe and may impair portability. My problem arises from the fact that a Vertex doesn't hold its own ID, it's a value object whose identity is solely determined by its memory location (its pointer), which is usually fine except for this normalization step! Note that I can't rely on the values of X, Y, Z coordinates for Vertex identity, because several Vertices may be at the same geographical position. Inspecting the values stored in each Vertex is irrelevant. Any creative idea ? This may be a starting point: https://play.golang.org/p/qvldUtH68C Thanks in advance :) -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
