Assigning mip level images manually

[giterino-0]

I can't figure out how to set every mip level image of a TextureCubeMap (without automatic mip generation), Are there any examples that do this?

[xarray]

Hi, to set mipmaps manually, you may use Image::setMipmapLevels() to setup a list of data offsets first, and copy mipmapping level-'i' to Image::getMipmapData(i). Everything is done in the image object instead TextureCubeMap.

[giterino-0]

As far as i checked, mip offsets in an Image are controlled by a list of indices (_mipmapData) that is cleared on the first line of Image::allocateImage() and Image::setImage(), resulting in the allocated block (_data) to only have enough memory for mip 0.
So either there are more ways to allocate the image that i missed, or _mipmapData is simply ignored.
Thanks for your time.

[LaurensVoerman]

Hi giterino, the trick is to allocate the buffer yourself and pass it to setImage. an example can be found in the dds reader/writer: OpenSceneGraph\src\osgPlugins\dds\ReaderWriterDDS.cpp short summary: unsigned char* imageData = new unsigned char [sizeWithMipmaps]; //fill data buffer with image and mipmaps, fill mipmap_offsets osgImage->setImage(s,t,r, internalFormat, pixelFormat, dataType, imageData, osg::Image::USE_NEW_DELETE, packing); if (mipmap_offsets.size()>0) osgImage->setMipmapLevels(mipmap_offsets); regards, Laurens.

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On Mon, Jan 13, 2025 at 9:56 AM giterino-0 ***@***.***> wrote: As far as i checked, mip offsets in an Image are controlled by a list of indices that is cleared on the first line of Image::allocateImage() _( *mipmapData)*, causing the allocated block _(*data)* to only have enough memory for mip 0. So either there are more ways to allocate the image that i missed, or _mipmapData is simply ignored. Thanks for your time. — Reply to this email directly, view it on GitHub <#1353 (reply in thread)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AEXFTWQQG4BDQPM4ZWKVICL2KN5R7AVCNFSM6AAAAABU7YNKLWVHI2DSMVQWIX3LMV43URDJONRXK43TNFXW4Q3PNVWWK3TUHMYTCOBRG43DENQ> . You are receiving this because you are subscribed to this thread.Message ID: <openscenegraph/OpenSceneGraph/repo-discussions/1353/comments/11817626 @github.com>

[giterino-0]

Note for other readers that setMipmapLevels() must come AFTER setImage(), otherwise it wouldn't work. which isn't obvious at all just by looking at the declarations.

[giterino-0]

I tried your answer but noticed one odd behaviour, if i call setMipmapLevels() i get "GL Error when compiling TextureCubeMap" and the texture is fully black.

The texture:

• has its filter mode set to LINEAR_MIPMAP_LINEAR

Also tried the following functions, to no avail:

• Texture::setUseHardwareMipMapGeneration()
• Texture::setNumMipmapLevels()
• Texture::setInternalFormatMode(USE_IMAGE_DATA_FORMAT)