Load The Texture

The first part of loading sprites into Amethyst is to read the image into memory.

The following snippet shows how to load a PNG / JPEG / GIF / ICO image:

extern crate amethyst;
use amethyst::assets::{AssetStorage, Handle, Loader};
use amethyst::prelude::*;
use amethyst::renderer::{formats::texture::ImageFormat, Texture};

pub fn load_texture<N>(name: N, world: &World) -> Handle<Texture>
where
    N: Into<String>,
{
    let loader = world.read_resource::<Loader>();
    loader.load(
        name,
        ImageFormat::default(),
        (),
        &world.read_resource::<AssetStorage<Texture>>(),
    )
}

#[derive(Debug)]
struct ExampleState;

impl SimpleState for ExampleState {
    fn on_start(&mut self, data: StateData<'_, GameData<'_, '_>>) {
        let texture_handle = load_texture("texture/sprite_sheet.png", &data.world);
    }
}

fn main() {}

There is one thing that may surprise you.

• You don't get back the Texture, but a Handle<Texture>, which is a cloneable reference to the texture.

  When you use loader.load(..) to load an Asset, the method returns immediately with a unique handle for your texture. The actual asset loading is handled asynchronously, so if you attempt to use the texture handle to retrieve the texture, such as with world.read_resource::<AssetStorage<Texture>>().get(texture_handle), you will get a None until the Texture has finished loading.

The loaded texture will use nearest filtering, i.e. the pixels won't be interpolated. If you want to tweak the sampling, you can change ImageFormat::default() to ImageFormat(my_config), and create your own my_config like this:

extern crate amethyst;
use amethyst::renderer::rendy::hal::image::{Filter, SamplerInfo, WrapMode};
use amethyst::renderer::rendy::texture::image::{ImageTextureConfig, Repr, TextureKind};

let my_config = ImageTextureConfig {
    // Determine format automatically
    format: None,
    // Color channel
    repr: Repr::Srgb,
    // Two-dimensional texture
    kind: TextureKind::D2,
    sampler_info: SamplerInfo::new(Filter::Linear, WrapMode::Clamp),
    // Don't generate mipmaps for this image
    generate_mips: false,
    premultiply_alpha: true,
};