Strawberries, on 29 November 2012 - 08:44 PM, said:
Thank you for the prompt and informative response.
This fixed it, but if you have any time could you explain to me a little bit about what CTM is and why I was having that problem?
CTM means Connected Textures Mod. It allows for blocks to be textures based on how they are "connected" to other blocks, have random textures, use a pattern over a large area, and have more different textures per block (like a top face different than the side faces, or side faces different from each other).
You had this issue because of how Optifine implements CTM. It loads it from the default ctm.png even when a texture pack is used, resulting in "defaulted" CTM textures.
As soon as you add extended CTM for any block that uses the classic CTM sheet (glass, bookshelves, sandstone), Optifine will stop trying to use the default ctm.png for anything except glass panes. You can fake that out, too by making all of the glass tiles on ctm.png have the same texture as non-connected glass.