How can I create a KTX2 texture from buffer that is in memory and save it to a file?

[GasimGasimzada]

I can't figure out how to use the KTX writer module or just manually create a KTX2 texture. I am looking at the following API reference: https://www.khronos.org/ktx/documentation/libktx/group__writer.html

Firstly, I do not have access to ktxWriteKTXF. I checked the include file in this repo as well. The function does not exist. So, I tried to use the create function:

ktxTexture *tex = nullptr;

// This function does not exist. Only ktxTexture2_Create exists
// but there are no counterparts for ktxTexture_SetImageFromMemory that
// allows using ktxTexture2
auto res = ktxTexture_Create(&createInfo, KTX_TEXTURE_CREATE_ALLOC_STORAGE,
                               &ktxTexture);

ktxTexture_SetImageFromMemory(
    ktxTexture, 1, 1, 1, static_cast<const ktx_uint8_t *>(textureDataLoadedFromSTB),
    textureSize);

FILE *file = fopen(fileName.string().c_str(), "wb");
ktxTexture_WriteToStdioStream(ktxTexture, file);

What am I missing here? How can I access the writer API?

I am using KTX4.0.0 and building it with the following Cmake flags:

"KTX_FEATURE_TESTS": "OFF",
"KTX_FEATURE_TOOLS": "OFF",
"KTX_FEATURE_VULKAN": "OFF",
"KTX_FEATURE_KTX1": "OFF",
"KTX_FEATURE_STATIC_LIRBARY": "ON",

[MarkCallow]

Somehow you have ended up at a very old version of the documentation. ktxWriteKTXF was deprecated a very long time and subsequently removed. Here is the latest version of the page you were looking at. See also the Introduction of the libktx documentation for a good summary of how to do various things with the library.

How did you end up at that page? I don't see a link to it on the KTX landing page at www.khronos.org/ktx or any of the pages linked from there. The only link I found points to the documentation I just pointed you to.

I'll ask the Khronos Webmaster to update https://www.khronos.org/ktx/documentation.

[GasimGasimzada]

That's my bad and it makes sense now 😄 I just googled the docs and it took me to this page. The URL pointed me to this the khornos domain; so, I thought it was official one.

[baiwenbo1997]

Hello, I am an initiator. I would like to convert the PNG format into KTX2 format, how should I operate? I refer to https://github.khronos.org/ktx-software/libktx/index.html#writektx, it should be that the way does not have the created KTX2 is not correct, do you have a more detailed example? thank you very much

[GasimGasimzada]

In that page, the section titled "Writing a KTX or KTX2 file" worked for me for KTX2 file.

[MarkCallow]

@baiwenbo1997 the ktxTexture2_Write* functions write a ktxTexture2 object in memory to a file. That is they serialize existing KTX2 data. They do not do any conversion. Use toktx to create KTX2 files from PNG files. If you want to write your own software to do this, also look at toktx to see how to do it.