OptiFine Connected Textures & Transitions Addon for PureBDcraft uses an OptiFine feature to let certain blocks connect to allow for smoother looking builds.
Some blocks – such as grass, snow, gravel, and sand – are also given blended edges so visual transitions are less jarring.
Please be aware of the following if you’re using the 512x main pack
Due to technical limitations you must have a Nvidia 10 series or better graphics card, as support for a 32,768 pixel texture atlas is required.
There are currently no Intel or AMD graphics cards that support that size atlas, so those users must use 256x or lower.
For Minecraft 1.13 and below Connected Textures are included in the main resource pack.