Assets in Hazel are reference counted, and should always be wrapped in a Ref instance. Meaning you should pretty much never allocate an Asset on the stack, since Hazel uses intrusive reference counting, meaning the reference count is stored in the asset instance, not in the Ref instance.
In order to retrieve an Asset you have to request it from the AssetManager class.
Example 1
...
Ref<PhysicsMaterial> material = AssetManager::GetAsset<PhysicsMaterial>(assetID);
...
Example 2
It's also possible to get an asset by the file path (relative to the projects "Assets" directory).
AssetHandle assetID = AssetManager::GetAssetHandleFromFilePath("Physics/PlayerMaterial.hpm");
Ref<PhysicsMaterial> material = AssetManager::GetAsset<PhysicsMaterial>(assetID);
// OR
Ref<PhysicsMaterial> material = AssetManager::GetAsset<PhysicsMaterial>("Physics/PlayerMaterial.hpm");
NOTE: Referencing Assets by ID is the preferred method
Creating New Assets
Most of the time you won't need to create assets programmatically, but Hazel does support doing so.
Ref<PhysicsMaterial> newMaterial = AssetManager::CreateNewAsset<PhysicsMaterial>("MyMaterial.hpm", "Physics/", ...);
The first two parameters are filename and directoryPath. After the first two parameters you can pass a variable number of parameters that will be used to construct the Asset instance.
Ref<SomeTextAsset> asset = AssetManager::CreateNewAsset<SomeTextAsset>("MyTextFile.txt", "Docs/", "This string will be passed to SomeTextAsset's constructor!");