See the multiblock before you build it — then let a ghost projection guide you block by block.

This is a client-side addon for Just Enough Mekanism Multiblocks (JEMM). JEMM already tells you what a Mekanism multiblock costs at a given size — this mod shows you what it looks like and how to build it.

✨ Features

🔍 View in 3D

Every JEMM multiblock page gets a "View in 3D" button. It opens an interactive 3D view of the structure exactly as you configured it in JEMM — dimensions, glass, valves/ports, steam height, heating elements, rotors/vents/condensers, even the advanced Fission layout.

Mouse wheel — zoom
Left/right drag — rotate
R — reset the camera
↑ / ↓ — slice the structure layer by layer (stacked or single-layer mode)
Click a block — see its name and position

👻 Project 3D — in-world building guide

The "Project 3D" button encodes the configured structure into a ghost hologram that follows your crosshair in the world:

Right-click — anchor the guide where you're aiming
R — rotate it 90°
V — show/hide, Sneak+V — pick it up and re-place it
Arrow keys — nudge the anchor one block at a time (Sneak = up/down)

While you build, blocks you place correctly disappear from the guide; wrong blocks get a red outline. Build the guide as shown and the multiblock forms — the layouts follow Mekanism's own formation rules.

All six keybinds are configurable, and the ghost opacity / camera sensitivity / default zoom are in the client config.

📦 Supported multiblocks

Mekanism: Dynamic Tank, Thermal Evaporation Plant, Thermoelectric Boiler, Supercritical Phase Shifter (SPS), Induction Matrix
Mekanism Generators: Industrial Turbine, Fission Reactor (including the advanced layout editor), Fusion Reactor
Addon multiblocks (when the addon is installed): Better Fusion Reactor (Better Fusion Reactor for Mekanism), Reinforced Induction Matrix & Naquadah Reactor (Mekanism Extras), Advanced Power Tower (Evolved Mekanism)

🧩 Requirements

Just Enough Mekanism Multiblocks — required (7.x)
Mekanism — required (10.7+)
JEI — required
Mekanism Generators — optional

Minecraft 1.21.1, NeoForge, Java 21.

Client-side only — safe to add to any client; nothing is required on the server. It works on servers that don't have the mod (the projection is purely visual, no item, no packets).

EMI note: the 3D buttons only appear with the regular JEI runtime. If EMI replaces JEI's recipe screens, JEMM runs through JEMI and the buttons are unavailable.

🛠️ For addon developers

If your mod adds its own JEMM category, you can plug in a 3D structure builder via StructureBuilderRegistry and a IStructureBuilderProvider ServiceLoader entry — resolution walks the widget class hierarchy, so widgets extending known JEMM widgets inherit their 3D rendering automatically.

📜 Credits & license

MIT. Structure layouts are derived from Mekanism's formation code and JEMM's cost formulas (both MIT) — see THIRD_PARTY_LICENSES.md in the repository. Huge thanks to giselle (JEMM) and the Mekanism team.

Mekanism: Multiblock 3D Viewer