Hello ,
I have started using ASTC recently ,observed some corruption on ASTC texture compressed using 12x12 veryfast using Mali Texture Compression Tool v4.1.0.
Is this expected as 12x12 -veryfast is the lowest quality compression ?
Using -veryfast with other block sizes or 12x12 -fast option does not have this issue.
Thank you,Rohit
In short - yes.
Like most real-time compression formats ASTC is a lossy compression scheme, so rendering artefacts are possible. The quality of the compression depends heavily on how much of the search space (which is very large for ASTC) the compressor manages to search. In -veryfast mode the compressor sacrifices the depth of this searching for faster compression performance, so that will give worse output than the slower modes.
In general I find -veryfast really useful for initial exploration of the compression levels, but for final asset export for a game I would suggest using one of the more thorough search modes (which will take longer to compress), as you'll get better visual output.
That said ... your artefacts are particularly ugly, so I will raise with the compression tool team - there is a good chance there is something going wrong here.
HTH, Pete
Rohit,
Clearly, this is not correct!
As Pete says, the different speed modes in the compressor work by restricting the search space of the compression algorithm. It looks like these blocks are somehow completely outside the -veryfast search space and end up as a default grey color. I will pass this on to the compression team and see if we can work out exactly what is going on.
In the meantime, at least you have a workaround, which is to use -fast mode. I hope that this is sufficient to keep you going for now.
Thanks for bringing this to our attention.
Sean.