Custom nodes that pack PBR material maps into labPBR 1.3 (Java Edition — Iris/OptiFine) and Bedrock RTX resource-pack textures, entirely on the GPU.

These are packer nodes — they don't run any model. They're built to consume the IMAGE outputs of the ComfyUI-Chord material-estimation node (basecolor, normal, roughness, metalness), but accept those maps from any source.

Nodes (category Minecraft PBR)

| Node | Purpose | |------|---------| | Pack labPBR | albedo + specular _s (smoothness/F0/porosity·SSS/emission) + normal _n (XY/AO/height) | | Pack Bedrock RTX | albedo + DirectX _normal + _mer (R=metal, G=emissive, B=roughness); _mers when SSS is enabled | | Pack Metal Masks | one region MASK per labPBR metal (iron/gold/aluminum/chrome/copper/lead/platinum/silver/custom) → a per-pixel metal-id map for the packer's metal_mask | | Save labPBR | writes name.png, name_s.png, name_n.png (linear RGBA) | | Save Bedrock RTX | writes name.png, name_normal.png, name_mer.png / _mers.png | | Derive AO + Height | AO (normal divergence) + POM height (Frankot–Chellappa) → two MASKs | | Extract Emission | luminance-threshold a basecolor → emission MASK |

roughness and metalness inputs accept IMAGE or MASK, so Chord's 1-channel IMAGE outputs wire straight in. The _s and _n textures flow as 4-channel RGBA IMAGE tensors; use the Save nodes to write valid alpha-bearing PNGs (the stock SaveImage node drops alpha).

Channel reference

labPBR _s (all linear): R = perceptual smoothness 1 − √roughness · G = F0/metal id (dielectric ≈ 10, metals 230–237, custom 255) · B = porosity (0–64) or SSS (65–255), SSS wins per-pixel · A = emission (0/255 = none, 1–254 = level).

labPBR _n: R/G = normal X/Y in DirectX (Y-down) convention · B = ambient occlusion · A = POM height (0.25 = 25% block depth … 1.0 = surface). The packer flips an OpenGL Y-up input to DirectX by default (flip_normal_y).

Bedrock _mer/_mers (all linear): R = metalness · G = emissive · B = roughness · A (MERS) = SSS thickness (zeroed where metallic). The SSS alpha (MERS) is read only by Vibrant Visuals; ray-traced (RTX) mode ignores it and uses plain _mer.

Typical graph

ComfyUI-Chord ─ basecolor ┐
              ─ normal    ┤→ Pack labPBR → albedo/specular/normal → Save labPBR
              ─ roughness ┤
              ─ metalness ┘

The packer derives AO + height from the normal automatically; toggle compute_porosity / compute_sss / compute_emission and pick a hardcoded_metal as needed. Wire the Derive / Extract nodes in only when you want to preview or edit those channels before packing.

Multiple metals in one texture

For a surface mixing metal types (e.g. a copper face with a chrome border), paint a region MASK per metal, feed them into Pack Metal Masks, and wire its metal_mask output into Pack labPBR's metal_mask input. Painted pixels get that metal's exact labPBR id in the specular green channel (iron 230 … silver 237, custom 255), overriding both hardcoded_metal and the metalness threshold; unpainted pixels fall back to normal behaviour. Overlapping regions resolve last-wins (named metals over custom).

Install

Clone or symlink this folder into ComfyUI/custom_nodes/ and restart ComfyUI. No extra Python dependencies. Reference: https://shaderlabs.org/wiki/LabPBR_Material_Standard.