Show HN: TRELLIS.2 image-to-3D running on Mac Silicon – no Nvidia GPU needed

Run TRELLIS.2 image-to-3D generation natively on Mac.

This is a port of Microsoft's TRELLIS.2 — a state-of-the-art image-to-3D model — from CUDA-only to Apple Silicon via PyTorch MPS. No NVIDIA GPU required.

Generates 400K+ vertex meshes from single images in ~3.5 minutes on M4 Pro.

Output includes vertex-colored OBJ and GLB files ready for use in 3D applications.

• macOS on Apple Silicon (M1 or later)
• Python 3.11+
• 24GB+ unified memory recommended (the 4B model is large)
• ~15GB disk space for model weights (downloaded on first run)

# Clone this repo
git clone https://github.com/shivampkumar/trellis-mac.git
cd trellis-mac
# Log into HuggingFace (needed for gated model weights)
hf auth login
# Request access to these gated models (usually instant approval):
# https://huggingface.co/facebook/dinov3-vitl16-pretrain-lvd1689m
# https://huggingface.co/briaai/RMBG-2.0
# Run setup (creates venv, installs deps, clones & patches TRELLIS.2)
bash setup.sh
# Activate the environment
source .venv/bin/activate
# Generate a 3D model from an image
python generate.py path/to/image.png

Output files are saved to the current directory (or use --output to specify a path).

# Basic usage
python generate.py photo.png
# With options
python generate.py photo.png --seed 123 --output my_model --pipeline-type 512
# All options
python generate.py --help

| Option | Default | Description | |---|---|---| --seed | 42 | Random seed for generation | --output | output_3d | Output filename (without extension) | --pipeline-type | 512 | Pipeline resolution: 512 , 1024 , 1024_cascade |

TRELLIS.2 depends on several CUDA-only libraries. This port replaces them with pure-PyTorch and pure-Python alternatives:

| Original (CUDA) | Replacement | Purpose | |---|---|---| flex_gemm | backends/conv_none.py | Sparse 3D convolution via gather-scatter | o_voxel._C hashmap | backends/mesh_extract.py | Mesh extraction from dual voxel grid | flash_attn | PyTorch SDPA | Scaled dot-product attention for sparse transformers | cumesh | Stub (graceful skip) | Hole filling, mesh simplification | nvdiffrast | Stub | Differentiable rasterization (texture export) |

Additionally, all hardcoded .cuda() calls throughout the codebase were patched to use the active device instead.

Sparse 3D Convolution (backends/conv_none.py): Implements submanifold sparse convolution by building a spatial hash of active voxels, gathering neighbor features for each kernel position, applying weights via matrix multiplication, and scatter-adding results back. Neighbor maps are cached per-tensor to avoid redundant computation.

Mesh Extraction (backends/mesh_extract.py): Reimplements flexible_dual_grid_to_mesh using Python dictionaries instead of CUDA hashmap operations. Builds a coordinate-to-index lookup table, finds connected voxels for each edge, and triangulates quads using normal alignment heuristics.

Attention (patched full_attn.py): Adds an SDPA backend to the sparse attention module. Pads variable-length sequences into batches, runs torch.nn.functional.scaled_dot_product_attention, then unpads results.

Benchmarks on M4 Pro (24GB), pipeline type 512:

| Stage | Time | |---|---| | Model loading | ~45s | | Image preprocessing | ~5s | | Sparse structure sampling | ~15s | | Shape SLat sampling | ~90s | | Texture SLat sampling | ~50s | | Mesh decoding | ~30s | | Total | ~3.5 min |

Memory usage peaks at around 18GB unified memory during generation.

No texture export: Texture baking requires nvdiffrast (CUDA-only differentiable rasterizer). Meshes export with vertex colors only. Hole filling disabled: Mesh hole filling requires cumesh (CUDA). Meshes may have small holes. Slower than CUDA: The pure-PyTorch sparse convolution is ~10x slower than the CUDA flex_gemm kernel. This is the main bottleneck. No training support: Inference only.

The porting code in this repository (backends, patches, scripts) is released under the MIT License.

Upstream model weights are subject to their own licenses:

• TRELLIS.2: MIT License
• DINOv3: Meta custom license (gated, review before commercial use)
• RMBG-2.0: CC BY-NC 4.0 (non-commercial; commercial use requires a license from BRIA)