| 1 | Texture cache readme file
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| 2 | -------------------------
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| 3 |
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| 4 | The texture management works as follows. I'll highlight the changes from Jonathans original implementation.
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| 5 |
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| 6 | Each texturemanager has a heap manager (or a non-heap manager). I've implemented each in
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| 7 | tex_heap.hh and tex_no_heap.hh. tex_heap is used when you have actual access to the texture memory
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| 8 | chunk, as with the software or Glide implementation of R1, however with something like Direct3D or
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| 9 | OpenGL, you dont, so the non-heap manager will keep track of those textures, how much memory they're using,
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| 10 | how old they are, etc.
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| 11 |
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| 12 | Aside from the heap manager, each texture manager has to implement an immediate_mip_load() and async_mip_load().
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| 13 | What each does should be obvious from the name. The way I have the async loads handled currently is that
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| 14 | the reads are started during the frame, but the upload isnt processed until next_frame() is called. Most
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| 15 | cards wont like it if you upload in mid-frame, so if you DO find yourself wanting to call immediate_mip_load(),
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| 16 | make sure its not in the middle of the frame.
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| 17 |
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| 18 | Aside from that, the texture managers dont do much other than "select" a texture. The reason the "select"
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| 19 | function exists is so the heap manager can keep track of how old textures are, but not much else. It could
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| 20 | do other things if the texture manager wants to implement a 2d tile system of combining textures, or whatever,
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| 21 | but it currently does nothing of the sort.
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| 22 |
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| 23 | As far as the texture file system goes, its a bit complicated.
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| 24 |
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| 25 | There is a texture directory (a physical directory, c:\tmp\ctext)
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| 26 | and a file inside of it called the "cache" file (c:\tmp\ctext\tex_cache.dat).
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| 27 | The cache knows what pixel format the textures in the directory are in, the
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| 28 | maximum size of the textures, and it also contains their lowest mip levels.
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| 29 | The reason it contains the lowest levels is to speed up the game startup, but
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| 30 | I've noticed its rather useless because the game still has to chunk on the
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| 31 | higher miplevels that it needs when you actually start drawing scenes.
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