crystal.assets.add_loader

Adds support for a new asset type. This allows you to integrate arbitrary content types with Crystal’s asset management system.

Usage

crystal.assets.add_loader(extension, loader)

Arguments

Name	Type	Description
`extension`	`string`	File extension (without `.` prefix) of assets for which this loader will be considered.
`loader`	`table`	Table describing the loader behavior.

The loader table may define any number of the following functions:

can_load(path: string): Must return a boolean indicating whether the file located under path is readable by this loader. You should implement this when multiple loaders apply to the same file extension. An example of this is lua assets, which can be maps, spritesheets or packages.
dependencies(path: string): Must return a list of asset paths which will be loaded before this one, and kept in memory as long as this asset is kept in memory.
load(path: string): Must return the actual asset that will be kept referenced by Crystal, and made available through crystal.assets.get.
unload(path: string): Called when Crystal drops its last reference to the asset. The asset and its dependencies are still available via crystal.assets.get during this call.

For assets with the lua file extension, Crystal will require() the file before selecting and applying a loader. After its loader finishes, the file is automatically un-required by clearing its entry in the package.loaded table.

Examples

This example shows how the image loader that is included with Crystal is implemented:

crystal.assets.add_loader("png", {
  load = function(path)
    return love.graphics.newImage(path);
  end,
});

This example shows how the package loader that is part of Crystal is implemented:

crystal.assets.add_loader("lua", {
  can_load = function(path)
    local raw = require(path:strip_file_extension());
    return raw.crystal_package == true;
  end,
  dependencies = function(path)
    local raw = require(path:strip_file_extension());
    assert(type(raw.files) == "table");
    return raw.files;
  end,
});