im not caring about quality issues just speed.
A/ 8bit alpha/intensity texture (best quality results but perhaps slower than B,C,D)
B/ dxt5 (same memory as #A but i assume a slight overhead for unpacking, is this correct?)
C/ dxt1 (ie rgb as intensity)
D/ others?
zed
A) should be fastest, the others only use less memory, but B and C do produce more texture reads than A, so they may be slower.
I don’t know of anything that would fit into D, but the speed diff would not be that large compared to a corectly filtered luminance texture.
C) is fastest.
D) is slowest.
Humus, just so I understand this right - using RGB DXT1 for intensity is faster than using a plain (should be 1Bpp internally AFAIK) intensity texture?
Is that ATI-specific (not included in OP’s question), or is this performance statement true for all existing hardware and software implementations supporting DXT1?
I’d always assumed texture cache coherency is the reason compressed textures are faster that uncompressed. You can fit more texture area in the cache if it’s compressed.