Piston and Observer

This mod backports sticky blocks (slime/honey) and observers to 1.7.10.

Dependencies

• Unimixin (https://github.com/LegacyModdingMC/UniMixins/)
• GTNH Lib (https://github.com/GTNewHorizons/GTNHLib)
• LibPiston (https://github.com/NinthTechMC/LibPiston)

Piston Features

Piston behavior is modified so that blocks that are stuck to sticky blocks will be moved together. You can configure if vanilla pistons are changed to this, or new piston and sticky piston blocks with this behavior are added (new blocks won't have recipes).

What are "sticky blocks"? This mod provides a slime block implementation and a honey block one to mimic vanilla behavior. By default, they are only added if no compatible mods are detected.

Compatible mods include:

• Tinker's Construct's green and blue congealed slime blocks (green and blue don't stick to each other)
• Biomes O Plenty's honey block

You can also add more to the config, and also config what will not stick to what.

Observer Features

Observers are not TileEntities (anymore). They are movable by pistons and can be used to create flying machines.

What works by default without individual tweaks (non-exhaustive):

• Any block change or metadata change (even when they don't cause block update)
• Flying machine
• Clock (by having 2 observers face-to-face)
• Place potion on Brewing Stand
• Placing flower in flower pot

Some tweaks to vanilla blocks are needed to have their state changes detected by observers like in later versions. Every such modification has a config that you can turn off if it causes conflicts with other mods.

• Doors opening/closing notify observers looking at both door blocks.
• Grass blocks changing between snowed and non-snowed states.
• Note blocks changing pitch, instrument, or powered state.
• Redstone Repeaters changing between locked and unlocked states.

Observer API

This mod provides an API for other mods to integrate into the observer system:

• ObserverAPI to notify observers in the world of some change
• IBlockObservable for blocks to override how they notify observers
  • for example, vanilla observers notify themselves when moved by pistons
  • you can also make a block only notify observers in a certain direction, for example
• IBlockObserver for blocks to become an observer
• Subscribe to ObserverEvent to be notified whenever any block is changed. This allows observer updates for interactions between blocks that are not part of the block state, like note block instruments and grass block snowyness

Contribution

Contributions are welcome. Feel free to open issues/PRs if there is a bug or observer feature missing.

Dev Setup

Using mcmod to generate a project with the GTNH Example Mod. You can either use mcmod to interact with the generated project or develop in the generated project directly