I am using the following command on Ubuntu 13.04:
./bin/etcpack file_name.png folder_name -s slow -c etc1 -e perceptual -f RGB -aa
which should generate an etc1 atlas with alpha channel included bellow the rgb image.
When alpha channel is 0 or 255 in original image, the result image is fine, and the alpha image contains in all channels a value identical to alpha in the original image.
When it has intermediate values, then I get in result image smaller alpha than in the original, something like ~ alpha_original/3, but it is not consistent.
When doing the same thing from UI, I get expected values, ie original alpha is replicated in all channels of alpha image.
Is it a bug, or am I missing something?
Hi ylog!
I've tried to reproduce the problem with a sample PNG file, but in my environment using Mali Texture Compression Tool has exactly the same effect as using etcpack with the options you have provided.
Could you please upload the PNG image that causes etcpack to miscalculate the alpha channel values?
Thanks,
Jacek