Buffers

These functions can be used to read and write directly to the device buffer memory.

A binary buffer is a region of physical memory used to temporarily hold data while it is being moved from one place to another or manipulated in some way, for example you can use a buffer to hold packet data awaiting transmission over a network or for storing a packet that has been received over a network. GameMaker: Studio has a number of specific functions related to creating, modifying and loading/saving buffers, but before using them please note the following points:

• When a buffer is created, it is automatically cleared and filled to 0.
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• The "size" argument of the buffer functions always refers to the size in bytes of the buffer.
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• The "Alignment" argument refers to how data is stored within a buffer. If your alignment is set to say, 4, and you write a single piece of data which is 1 byte in size then do a buffer_tell, you'll get an offset of 1. However, if you write another piece of data, also 1 byte in size, then do a buffer_tell, you'll get an offset of 5 as the alignment has "padded" the data to that size. Alignment only affects where things are written to, so if you do a buffer_tell after you write something, it'll return the current write position which immediately follows the data you've written. Note, however, that if you then write another piece of data, internally the buffer will move the write position along to the next multiple of the alignment size before actually writing the piece of data.
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• When dealing with "offset", this is the value in bytes to offset the data by within the given buffer. So if your buffer is 2 byte aligned and you want to skip the first 4 aligned places, you would have an offset of 2 * 4 bytes.
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• Some of the buffer functions also create a new buffer (like buffer_load for example). Remember that these buffers will also need to be removed from memory when not in use using the buffer_delete function.
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• The memory used for creating buffers is system memory so even when the game doesn't have focus, any data stored in a buffer should be safe, however if the app is closed or re-started then it will be lost.

The following pages explain how buffers work within the context of GameMaker: Studio and contain a couple of code examples for those users that are unsure of how to use them:

1. Using Buffers
   
2. Buffer Examples
   

The following functions exist for you to use with binary buffers in your games:

1. buffer_create
   
2. buffer_create_from_vertex_buffer
   
3. buffer_create_from_vertex_buffer_ext
   
4. buffer_delete
   
5. buffer_read
   
6. buffer_write
   
7. buffer_fill
   
8. buffer_seek
   
9. buffer_tell
   
10. buffer_peek
    
11. buffer_poke
    
12. buffer_save
    
13. buffer_save_ext
    
14. buffer_save_async
    
15. buffer_load
    
16. buffer_load_ext
    
17. buffer_load_async
    
18. buffer_async_group_begin
    
19. buffer_async_group_option
    
20. buffer_async_group_end
    
21. buffer_copy
    
22. buffer_copy_from_vertex_buffer
    
23. buffer_get_type
    
24. buffer_get_alignment
    
25. buffer_get_address
    
26. buffer_get_size
    
27. buffer_get_surface
    
28. buffer_set_surface
    
29. buffer_resize
    
30. buffer_sizeof
    
31. buffer_md5
    
32. buffer_sha1
    
33. buffer_base64_encode
    
34. buffer_base64_decode
    
35. buffer_base64_decode_ext
    

There are also two extra functions related to buffers that can be used to save and load game states (note that they require a buffer to have been created previously):

1. game_load_buffer
   
2. game_save_buffer
   

Finally, you can also use special Vertex Buffers to create your own custom primitives or models, etc... You can find out more about these from the following section of the manual:

1. Vertex Buffers

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