Early Access: Mo Glass for NeoForge 1.21 & 1.21.3

Mo Glass

A Minecraft mod that adds glass stairs and glass slabs to the game, including stained and tinted glass variants, while maintaining all of the seamless transparency and translucency that makes vanilla Minecraft's glass blocks look so great.

A Minecraft house with its roof made out of glass stairs, powered by the Mo Glass mod

Features

Glass Slabs!
Glass Stairs!
Stained Glass Slabs! (since v1.3)
Stained Glass Stairs! (since v1.3)
Tinted Glass Slabs! (since v1.6)
Tinted Glass Stairs! (since v1.6)
Working Transparency! (see below)
Working Translucency! (for tinted glass)

Seamless Transparency

Both the stairs and the slabs are see-through in the same way as vanilla glass blocks. You can place multiple stairs, slabs and full blocks next to each other and they will look like a single piece of glass.

Working Translucency

Slabs and stairs made from tinted glass will block light if you place them without any air gaps, or let the light through if there is a gap.

Why aren't these blocks part of vanilla Minecraft?

Before I started making this mod, I always thought that Mojang just forgot about these blocks, or that they were too lazy to add them. But now that I've added these blocks myself and spent many hours to get the transparency to work, I think I finally understand why Mojang didn't bother. Minecraft's stairs are surprisingly complex blocks and they were never meant to be made transparent. Slabs might be easy enough, but I think if Mojang added those then people wouldn't stop asking for the stairs. And glass stairs are an absolute nightmare to make.

Stairs can be placed facing North, East, South or West, they can be upside-down or right-side-up, they can be straight or curved in one of four different ways and they have six faces that may or may not be transparent, depending on what block is next to them. But here's the catch: On each of those six faces, there could be another block of glass stairs that can also be placed facing North, East, South or West, upside-down or right-side-up and either straight or curved in one of four different ways. And then of course, on each of the six faces there could also be a non-transparent block, a regular glass block or a glass slab that is either placed on the bottom half, top half, or is a double slab.

In the end, there are 10800 possible scenarios that need to be accounted for just to calculate transparency of glass stairs. But then you also have to calculate the transparency of glass slabs (810 possible scenarios) and adjust the transparency calculation of regular glass blocks (270 possible scenarios, or 258 more than before).*

That's a lot of effort just to add two new blocks to the game - and a lot of opportunities for new bugs to sneak in. That, I think, is why Mojang didn't bother.

*Here's how I got those numbers: (click to expand)

possible variations of stairs: pvStairs = 4 * 2 * 5 = 40

possible variations of slabs: pvSlabs = 3

possible variations of glass blocks: pvGlass = 1

possible variations of non-transparent blocks: pvBlocks = 1 (because any variations would be ignored when calculating transparency)

possible combinations combined: pvAll = pvStairs + pvSlabs + pvGlass + pvBlocks = 40 + 3 + 1 + 1 = 45

possibly transparent faces of a block (including stairs, even though they have more faces): f = 6

possible scenarios for transparency of stairs: psStairs = pvAll * f * pvStairs = 45 * 6 * 40 = 10800

possible scenarios for transparency of slabs: psSlabs = pvAll * f * pvSlabs = 45 * 6 * 3 = 810

possible scenarios for transparency of glass blocks: psGlass = pvAll * f * pvGlass = 45 * 6 * 1 = 270

possible scenarios for transparency of glass blocks if glass stairs and slabs don't exist: psGlassVanilla = (pvGlass + pvBlocks) * f * pvGlass = (1 + 1) * 6 * 1 = 12