wfc
Single-file Wave Function Collapse library in C, plus a command-line tool
- License: MIT
- Version: 0.01
This is an early version that supports the overlapping WFC method. The method takes an input image and generates output image which is locally similar to the input image. Here're a few examples of input/output pairs:
For a good read on WFC see this article. It's particularly useful for procedural generation of game levels.
HOW TO USE THE LIBRARY
One file in your project should include wfc.h like this:
#define WFC_IMPLEMENTATION
#include "wfc.h"
Other files can also include and use wfc.h but they shouldn't define WFC_IMPLEMENTATION macro.
Usage:
struct wfc *wfc = wfc_overlapping(
128, // Output image width in pixels
128, // Output image height in pixels
input_image, // Input image that will be cut into tiles
3, // Tile width in pixels
3, // Tile height in pixels
1, // Expand input image on the right and bottom
1, // Add horizontal flips of all tiles
1, // Add vertical flips of all tiles
1 // Add n*90deg rotations of all tiles
);
wfc_run(wfc, -1); // Run Wave Function Collapse
// -1 means no limit on iterations
struct wfc_image *output_image = wfc_output_image(wfc);
wfc_destroy(wfc);
// use output_image->data
// wfc_img_destroy(output_image);
By default you work with struct wfc_image for inputs and outputs.
struct wfc_image {
unsigned char *data;
int component_cnt;
int width;
int height;
}
data is tightly packed without padding. Each pixel consists of component_cnt components (e.g., four components for rgba format). The output image will have the same number of components as the input image.
wfc_run returns 0 if it cannot find a solution. You can try again like so:
wfc_init(wfc);
wfc_run(wfc, -1);
Working with image files
wfc can optionally use stb_image.h and stb_write.h to provide convenience functions for working directly with image files.
You will normally place stb_image.h and stb_write.h in the same directory as wfc.h and include their implementations in one of the project files:
#define STB_IMAGE_IMPLEMENTATION
#define STB_IMAGE_WRITE_IMPLEMENTATION
#include "stb_image.h"
#include "stb_image_write.h"
Further, you will instruct wfc.h to use stb:
#define WFC_IMPLEMENTATION
#define WFC_USE_STB
#include "wfc.h"
Usage:
struct wfc_image *input_image = wfc_img_load("input.png");
struct wfc *wfc = wfc_overlapping(
...
input_image,
...
);
wfc_run(wfc, -1); // Run Wave Function Collapse
// -1 means no restriction on number of iterations
wfc_export(wfc, "output.png");
wfc_img_destroy(input_image);
wfc_destroy(wfc);
Extra functions enabled by the inclusion of stb:
struct wfc_image *image = wfc_img_load("image.png")
wfc_img_save(image, "image.png")
wfc_export(wfc, "output.png")
wfc_export_tiles(wfc, "directory")
// don't forget to wfc_img_destroy(image) loaded images
COMMAND-LINE TOOL
The command-line tool uses the library and allows to generate WFC images. The tool depends on stb_image.h and stb_write.h. Place both files in the same directory as wfctool.c.
make
./wfc
Run ./wfc to see available options
Basic usage:
./wfc -m overlapping -w 128 -h 128 input.png output.png
THANKS
Thanks for using wfc. If you find any bugs, have questions, or feedback please let me know. Also, if you'd like to share your works it's very appreciated.
samp.krystian at gmail.com
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