Struct piston_window::texture_packer::TexturePacker

pub struct TexturePacker<T> {
    pub textures: Vec<T, Global>,
    pub atlas: usize,
    pub skyline: Vec<[u32; 2], Global>,
}

A texture packer using a skyline heuristic.

For offline texture packing, see texture_packer.

Designed for adding textures one by one to current texture atlas. Packs tiles without backtracking or knowledge about future tiles.

• Perfect at packing tiles of same size
• Good at packing tiles of some unit size
• Decent at packing tiles of similar sizes
• Can be used with pre-sorted tile sizes for better packing

Can also be used as storage for textures.

Design

A skyline is a list of non-hole atlas offsets, used to efficiently determine a good place to put the next tile.

In this texture packer, only a single skyline is kept track of, since new texture atlases are created by need.

This texture packer has runtime complexity O(N^2) for inserting a new tile, where N is the number of points in the skyline. Since N is usually a low number, the packing is pretty fast.

The algorithm was designed by Sven Nilsen (2019) for Piston-Graphics.

Fields

textures: Vec<T, Global>

Stores current texture atlas and previously created ones.

atlas: usize

The index to the current texture atlas.

skyline: Vec<[u32; 2], Global>

Texture atlas offsets from left to right.

When a new tile is added with same offset, it updates the atlas offsets that it overlaps. This means that “holes” get filled in over time.

Implementations

impl<T> TexturePacker<T>where T: ImageSize,

pub fn new() -> TexturePacker<T>

Returns a new TexturePacker.

pub fn create(&mut self, size: [u32; 2], texture: T) -> usize

Create a new texture atlas with an initial tile.

The new texture atlas is made the current one.

pub fn update(&mut self, ind: usize, size: [u32; 2]) -> (usize, [u32; 2])

Update current texture atlas.

• ind: index of atlas offset in the skyline
• size: size of new tile

Returns the index of the current texture atlas and the atlas offset of the new tile.

pub fn find_space(&self, size: [u32; 2]) -> Option<usize>

Returns the index of atlas offset in skyline with room for a new tile.

Returns None if no room was found in the current texture atlas.