Currently there is no interface to the compressor to force the disabling of the toroidal wrapping (it’s not really GL_REPEAT, per se).
Instead -provided the quality is setting for the compressor is set high enough** - the compressor will try options with/without the interpolation and choose whichever scores better from an RMSE/PSNR point of view. Note also the interpolation can be turned off away from the borders as well.
For example the following is a 32x32 test image that has both continuous and discontinuous regions.
This has been compressed with both PVRTC1 and PVRTC2:
[attachment file=“leaf-test-TC1-scale.png”] … [attachment file=“leaf-test-TC2-scale.png”]
With PVRTC2 most of the green areas are being treated as ‘continuous’ by the compressor but it switches to other modes around the red/blue stripes etc.
Also, just for fun, I tried the same with DXT1
Having said this, it would be useful to add a feature to force the discontinuous mode at the edges of a texture so that they can more easily be assembled “on the fly” into atlases at runtime.
I need to confirm this, but IIRC the lowest quality doesn’t try the “don’t wrap” modes*
***This may change in future versions