https://github.com/preciz/wfc

Wave Function Collapse implemented in Elixir
https://github.com/preciz/wfc

algorithm elixir wave-function-collapse

Last synced: 9 days ago
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Wave Function Collapse implemented in Elixir

• Host: GitHub
• URL: https://github.com/preciz/wfc
• Owner: preciz
• Created: 2019-04-30T11:22:33.000Z (almost 6 years ago)
• Default Branch: master
• Last Pushed: 2019-11-11T15:17:12.000Z (over 5 years ago)
• Last Synced: 2024-12-07T22:12:27.177Z (2 months ago)
• Topics: algorithm, elixir, wave-function-collapse
• Language: Elixir
• Size: 12.7 KB
• Stars: 3
• Watchers: 2
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# WFC

Overlapping Wave Function Collapse algorithm implemented in Elixir.

One of the main goal is readability so codebase can be used for learning the algorithm.

[Paper to help understand the algorithm](https://adamsmith.as/papers/wfc_is_constraint_solving_in_the_wild.pdf)

[Wave Function Collapse repo](https://github.com/mxgmn/WaveFunctionCollapse)

## Try it out!

This will generate an example png for you in main dir.

```elixir

Wfc.example()

```

## How it works?

Let's say you have an input like the below one:

```elixir

  [

    [{255, 255, 255}, {255, 255, 255}, {255, 255, 255}, {255, 255, 255}],

    [{255, 255, 255}, {0, 0, 0}, {0, 0, 0}, {0, 0, 0}],

    [{255, 255, 255}, {0, 0, 0}, {255, 0, 0}, {0, 0, 0}],

    [{255, 255, 255}, {0, 0, 0}, {0, 0, 0}, {0, 0, 0}]

  ]

```

First you create NxN tiles from it. (optionally to make more tiles you rotate them around)

This happens in `Wfc.Input.tiles/2`.

```elixir

[

  [[{255, 255, 255}, {255, 255, 255}], [{255, 255, 255}, {0, 0, 0}]],

  [[{255, 255, 255}, {255, 255, 255}], [{0, 0, 0}, {0, 0, 0}]],

  [[{255, 255, 255}, {0, 0, 0}], [{255, 255, 255}, {0, 0, 0}]],

  [[{0, 0, 0}, {0, 0, 0}], [{0, 0, 0}, {255, 0, 0}]],

  ...

]

```

Now you need to determine which tiles can go next to each other in which directions.

This happens in `Wfc.Input.constraints/2`.

For example if you want to determine that `b_tile` can go above `a_tile`:

```elixir

  [a_tile_top_row | _] = a_tile = [[{255, 255, 255}, {255, 255, 255}], [{255, 255, 255}, {0, 0, 0}]],

  [_top_row | b_tile_bottom_row] = b_tile = [[{255, 255, 255}, {255, 255, 255}], [{255, 255, 255}, {0, 0, 0}]],

  can_b_tile_go_on_top_of_a_tile? = (a_tile_top_row == b_tile_bottom_row)

```

Now that you have your tiles with your constraints:

1. You create your output matrix and you set all elements to include all possible tiles. `Wfc.Output.new/2`

2. You set a random element to just 1 possible tile, and you propagate the changes to the neighbours. `Wfc.Output.collapse/1`

3. When the above propagation is ready, you select the element with lowest possibilities and you repeat step 2 until you have only elements with 1 possible tile. `Wfc.Output.lowest_possibilities_position/1`

4. You are done.