PrimitiveImporter.cs

[ScriptedImporter(1, "cube")]
public class PrimitiveImporter : ScriptedImporter
{
	public PrimitiveType type = PrimitiveType.Cube;

	public override void OnImportAsset(AssetImportContext ctx)
	{
		var cube = GameObject.CreatePrimitive(type);
		cube.transform.localScale = new Vector3(1, 1, 1);

		var material = new Material(Shader.Find("Standard"));
		material.name = "Cube Material";

		cube.GetComponent<MeshRenderer> ().material = material;

		try
		{
			var scale = JsonUtility.FromJson<Vector3>(File.ReadAllText(ctx.assetPath));
			cube.transform.localScale = scale;
		}catch (System.Exception e) {
			Debug.LogError (e.Message, cube);
		}

		ctx.AddObjectToAsset("mat", material);
		ctx.AddObjectToAsset("CUBE", cube);
		ctx.SetMainObject(cube);
	}
}