Imagination PowerVR SDK Blog

PVRTexTool does not display images for KTX cubemap texture

pvrtextool

#1

When I download and open https://github.com/SaschaWillems/Vulkan/raw/master/data/textures/cubemap_yokohama.ktx in PVRTexTool, it does not display any images. The image display area contains a single window, probably at the size of the base mip level of one of the faces, filled with grey.

I have tried the latest version 4.16.0. The previous version I was using had the same problem.

The cube map is 8.4MB so I won’t attempt to attach it here.


#2

Hi Mark,

I have tried that texture and it works fine for me, both as a single map and a cube map (PVRTexTool 4.16.0). Are you sure you do not have selected a lower mipmap level in the "surface browser"panel?

Regards.

Carlos.


#3

Yes I am absolutely sure I had level 0 selected in the surface browser panel.

The problem is with the OS X version of PTT. The Windows version, which I tried after starting this thread, displays the texture. I am running OS X 10.11.6 on a late 2011 MBP with AMD & Intel graphics. Currently it is using the AMD graphics because of another app that is running.


#4

Hi Mark,

Yes, I have reproduced the problem you have reported on Mac and we are looking into it. We are releasing a new SDK & Tools package in the next few weeks and we will try to get it fixed by then.

Thanks for reporting it!

Carlos.


#5

Hi Mark,

The problem with your KTX file is that it contains a DXTC (S3TC) compressed texture. For legal reasons DXTC only can be supported on Windows so the decompression fails on Mac/Linux. We are adding a warning to notify that the decompression has failed, but we cannot do more than that.

Regards.

Carlos.


#6

Hi Carlos,

Thanks for investigating. I do not understand why there is a legal issue. All 3 of the OpenGL renderers on my OS X 10.11.6 MBP (AMD, Intel and Apple Software) support GL_EXT_texture_compression_s3tc so clearly Apple, et al, have licensed the technology. You can use these to draw the texture images.


#7

Any word on why using GL_EXT_texture_compression_s3tc doesn’t solve the problem, if indeed it doesn’t?


#8

Hi Mark,

The application does not rely on any graphics API functionality to avoid dependencies. I will review the license terms to see what we can do on Mac.

Regards.

Carlos.


#9

The S3 patents have expired so you no longer have any excuse to not support displaying these images everywhere.

This is why OpenGL 4.6 includes S3 (aka DX) TC in core.


#10

Hi Mark,

Yes, you are right. Since March 2018 the S3TC patents have expired. As soon as we have green light from our legal department we should be able to support this format to Linux and Mac.

Regards.

Carlos.