1. DXT
(http://gamecode.org)
2009.10.11

2. DXT
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– DDS
– Nvidia
– DirectX (DirectX Texture Tool)
– ATI compressonator
• . DXT1, DXT3, DXT5

3. DXT ?
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– ,
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– : Allegorithmic "Substance Air“
• a new genetation of texture
• http://www.allegorithmic.com
• ~
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• DXT ~

4. DXT
• 4x4
– read 16
– Bilinear Filtering
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– (cache hit!!)
•
– dxt1 4x4 8
– 16 2*16 => 32 (1/4 )
(X8R8G8B8 1/8 )
•
– ( )
– ( )
–
• !!

5. DXT1 기본 알고리즘(1)
• 4x4
– 8
– 2 +2 +4
– 16 + 16 + 32
– 16 + 16 + (2 +2 + ... + 2 )
– RGB1(565:16) + RGB2(565:16) + T00(2) + T01(2) + T02(2) + T03(2) + T10(2) + T12(2) + ..
+ T33(2)
• PCA ( )
– (Eigen Vector)
– = ( )

6. DXT1 기본 알고리즘(2)
• 16
– PCA
– 3 (RGB)
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– RangeFit
– ClusterFit
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– 참고 : http:/ / code.google.com/ p/ libsquish/

7. DXT1 기본 알고리즘(3)
• Pseudo Code
???
(0, 1 RGB0,RGB1 )
•
– RGB0 >= RGB1
– DXT1 BLACK 0

8. DXT3/ DX5 알고리즘(1)
• DXT 3
– RGB DXT1
– 16 4 (8 )
• DXT5
– (RGB )
– 8
• 1 +1 +6
• 8Bit + 8Bit + 3Bit + 3bit ... + 3Bit
• ALPHA0(8) + ALPHA1(8) + T00(3) + T01(3) + .. + T32(3) + T33(3)
• RGB (8 )
– Pseudo Code

9. DXT3/ DX5 알고리즘(2)
– RGB BLACK 0, 255
• ALPHA1 ALPHA0 8 6+2
– Pseudo Code

10. • ( )
– ( )
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• HALO
– DXT5 , RGB ,
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• DXT
– : 16 DXT
• (Official)
– http://oss.sgi.com/projects/ogl-sample/registry/EXT/texture_compression_s3tc.txt