Add smoothBlend functionality to crispBlend for transparent texture mipmaps

[TorutheRedFox]

Description

Fixes water opacity in default texture pack, making it no longer fully opaque when mipmaps kick in.

Changes

Previous Behavior

Water was fading to opaque due to crispBlend destroying texture alpha in mipmaps.

Root Cause

This seems to be a long standing bug in LCE because they used Notch's crispBlend algorithm to blend texels when calculating mipmaps in realtime, which is intended for cutout textures, not transparent textures. Java edition scrapped the generation of mipmaps for a good while, but in its unused implementation it used smoothBlend to calculate the mips for textures that were supposed to be transparent, i.e. water. This PR just merges their functionality based on the detected alpha value of the pixels.

New Behavior

Transparent textures such as water keep their transparency in their mipmaps.

Fix Implementation

If both pixels involved in the blend operation have an alpha value less than 224, they'll be treated as transparent and the smoothBlend algorithm is used to blend the pixels instead, preserving the alpha in the process. If either pixel has an alpha value of 224 or more, crispBlend blends them as normal to avoid losing detail in cutout textures.

AI Use Disclosure

No AI was used in the making of this code.

[TorutheRedFox]

Video of how water now looks

2026-03-10.10-37-59.mp4

[codeHusky]

That does look a lot better. Was this particular bug ever fixed in LCE in like a future TU?

[TorutheRedFox]

i don't recall it ever getting fixed

[codeHusky]

While this does look better to me, if this is a departure from how LCE has historically looked it should be a setting to enable the fix rather than having it default on.

[TorutheRedFox]

i'd need some assistance with the swf modding then

[DeanLemans]

Could we get some before vs now photos?

[TorutheRedFox]

when i get home :P