DDS cubemap not possible

[GoogleCodeExporter]

Attempting to write DDS cubemap.
DDS Plugin won't let me select "Save: CubeMap"(dropdown is greyed out and says 
"Selected layer")
I created layers with same dimensions, named:
positive x,negative x,positive y,negative y,positive z,negative z

What steps will reproduce the problem?
1.File>Export As
2.Export
3.Save as DDS dialogue
greyed out:
Format
Save:
Transparent index:
when saving, it saves only the selected layer into the DDS (as expected by the 
greyed out selection, but not as desired. should be all layers in cubemap)

What is the expected output? What do you see instead?
selection possible in drop down 
"Save: Cube Map"
all layers in DDS as cubemap

What version of the product are you using? On what operating system?
gimp 2.8.10
win8 64

Please provide any additional information below.

Original issue reported on code.google.com by digitalb...@googlemail.com on 5 Jan 2014 at 4:05

[GoogleCodeExporter]

Try to make sure that all your layers have an alpha channel.  Currently, for 
exporting cube maps, all 6 layers (faces) have to be the same size and have the 
same format.  If you have created your cube map from scratch, make sure the 
"background" layer has an alpha channel added to it (Menu->Layer->Add Alpha 
Channel). If that does not help, let me know!

Original comment by ski...@gmail.com on 9 Jan 2014 at 8:21

[GoogleCodeExporter]

Thank you for your reply!
One of the layers, I believe indeed the initial "background" layer had no alpha 
channel.
While importing the rendered images, the alpha of only that one didn't make it 
because the default empty image in gimp has no alpha channel )8 duh.
Well spotted!

I guess this is an easy, not to mention dumb and avoidable mistake one cane 
make. 

If possible you should put a recommendation into documentation or ideally even 
have a dialogue/warning pop up telling what is missing/mismatching instead of 
just greying out the drop down without any hint.

I spent some time in the dark, trying to figure this out before giving up on 
playing with gimp and ended up frustratedly using an old ATI tool(which worked 
really well nonetheless).

Kudos to you guys though for making this plugin.
Thanks!

Original comment by digitalb...@googlemail.com on 10 Jan 2014 at 1:37

[GoogleCodeExporter]

Same problem. Adding alpha channel didn't seem to help. Agree it would be 
pretty useful if the plugin could show a pop-up indicating why the current 
images can't be exported to cubemap. 

Original comment by eodab...@gmail.com on 26 Feb 2015 at 4:40

[DragonHawkAlpha]

Just out of interest if anyone has read this post and was looking to use an HDRI on UE4 see this: https://docs.unrealengine.com/en-US/Engine/Rendering/LightingAndShadows/HDRIBackdrop/index.html