Using the .X File Format

Using the .X File Format

Using the .X File Format(11)      摘要: Skeletal animation systems require a frame hierarchy (which represents the bone structure) to orient each bone during rendering. The .X file format defines a frame−of−reference data template that you can use to define your bone hierarchy. This template, Frame, is merely a placeholder of sorts. It allows any type of data object to be embedded in it so you can reference the instanced Frame object by its assigned instance name and allow all contained objects to be addressed as well.  

 

Using the .X File Format(10)      摘要: Just as I promised, it's time to check out how to merge the mesh−loading functions into your .X parser class. Since you're going to be accessing the mesh data objects directly, you need to use the D3DXLoadMeshFromXof function to load mesh data. That means you need to parse each data object, and look for Mesh objects as you go. Start by deriving a parser class with which to work. 

 

Using the .X File Format(9)      摘要: Now that you've got a firm grip on how the .X file format works, consider how Microsoft first intended for you to use it−to contain 3D mesh information for your games. The D3DX library comes with a number of functions you can use to load mesh data from an .X file. With the addition of the .X parser developed in this chapter, you have even more options available to you. Check out just how easy it is to work with D3DX to load mesh data.  

 

Using the .X File Format(8)      摘要: So, you want to create a class to handle all aspects of parsing .X files, eh? Sounds great to me! In this .X file parser class, you can wrap up the Parse and ParseObject functions you saw earlier in this chapter, in the "Enumerating Data Objects" section. Use the code from those two functions and write the parser class to allow yourself to override the data object parsing functions, which will allow you to scan for specific objects. 

 

Using the .X File Format(7)      摘要: Remember that data objects are containers for data, and if you're going to the trouble to enumerate data objects, it's a safe bet that you're after the data in each one. Once you've got a valid IDirectXFileData object that points at an enumerated data object, you can retrieve the object's instance name, template GUID, and data using a trio of functions. The first function, IDirectXFileData::GetName, retrieves the name of the data object instance.  

 

Using the .X File Format(6)      摘要: At this point, you have opened your .X file and registered the templates you'll be using (such as the DirectX standard templates). The enumeration object has been created, and you are now ready to pull data from the .X file.

In its current state, the IDirectXFileEnumObject object you created points to the first data object in the file, which is typically the Header object. All top−level data objects are siblings of the Header object (or the first object in the file). Each data object yo  

 

Using the .X File Format(5)      摘要: Regardless of the version of DirectX you are using (either DirectX 8 or 9), the methods you use to access .X files are the same. In fact, the interfaces have not changed names between the two newest versions of DirectX (8 and 9), making it possible for you to quickly port your version 8 code to the newer version 9 (and vice versa if you want).  

 

Using the .X File Format(4)      摘要: some .X Standard Templates:  

 

Using the .X File Format(3)      摘要: Data referencing has one caveat−the template restrictions set in place must allow you to use a reference. That might not make sense at first, but you can't use a data reference without the proper restrictions. An .X file represents an entire hierarchy of data objects, which can only be siblings or children of other objects. Thus, data objects embedded in other objects need the proper restrictions to be referenced or instanced. For example, consider the following three template declarations:  

 

Using the .X File Format(2)      摘要: Since an .X file's open−ended design is so, well, open−ended, you must predefine each template that you intend to use for DirectX to understand how to access the template's data. Typically templates are defined inside an .X file, although you can define them from within your program (as I mentioned earlier).  

 

Using the .X File Format(1)      摘要: Your 3D meshes need a place to liverather, you need a place to store your 3D mesh data (not to mention all that other data your game project requires). What's a developer to do−develop his own file format or go with a third−party format? With so many popular formats out there, it's an easy choice to make, but what about the restrictions some formats impose? Why can't you just use somebody else's file format and configure it to work the way you want?