Roland Scheidegger wrote: > On 22.11.2008 02:00, Brian Paul wrote: >> Philipp Klaus Krause wrote: >>> In _mesa_compressed_texture_size(), texcompress.c there's lots of code >>> similar to the following: >>> >>> case MESA_FORMAT_RGBA_DXT1: >>> /* round up width, height to next multiple of 4 */ >>> width = (width + 3) & ~3; >>> height = (height + 3) & ~3; >>> /* 8 bytes per 4x4 tile of RGB[A] texels */ >>> size = width * height / 2; >>> /* Textures smaller than 4x4 will effectively be made into 4x4 and >>> * take 8 bytes. >>> */ >>> if (size < 8) >>> size = 8; >>> return size; >>> >>> What's the purpose of the if (size < 8) size = 8;? It seems redundant to me. >> IIRC, all DTX blocks are 4x4 texels in size and each such block is >> represented by 8 bytes. Images smaller than 4x4 pixels are still stored >> in 8-byte 4x4 blocks so we need to allocate that minimum amount of memory. >> >> -Brian > > I think the question was why it would be necessary to explicitly round > up the calculated size to 8, since width and height are rounded up > already and hence size can't be smaller than 8 anyway (unless height or > width would be zero, that is).
Call it an oversight, or defensive programming. :) -Brian ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ Mesa3d-dev mailing list Mesa3d-dev@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/mesa3d-dev
