sdf_export.py

import trimesh
import numpy as np
import mesh2sdf


def mesh_to_sdf_glsl(path, resolution=64):
    # Load mesh
    mesh = trimesh.load(path)

    # Center and scale the mesh to fit in [-1, 1] cube
    mesh.vertices -= mesh.centroid
    # Calculate the maximum extent of the mesh
    max_extent = np.max(np.abs(mesh.vertices))
    scale = 1.0 / max_extent
    mesh.vertices *= scale

    # Create a grid of points
    x = np.linspace(-1.0, 1.0, resolution)
    y = np.linspace(-1.0, 1.0, resolution)
    z = np.linspace(-1.0, 1.0, resolution)
    X, Y, Z = np.meshgrid(x, y, z)

    # Flatten the grid and reshape to (n,3)
    query_points = np.column_stack((X.ravel(), Y.ravel(), Z.ravel()))

    # Calculate signed distances using mesh2sdf
    distances = mesh2sdf.compute(
        mesh.vertices, mesh.faces, query_points, return_gradients=False
    )

    # Normalize distances to [-1, 1]
    distances = np.clip(distances, -1.0, 1.0)

    # Convert to GLSL array
    glsl_array = ", ".join(f"{v:.6f}" for v in distances)

    glsl_code = f"""// Auto-generated SDF GLSL from mesh
float sdfData[{resolution**3}] = float[](
    {glsl_array}
);

float SDF(vec3 p) {{
    vec3 dim = vec3({resolution}.0);
    vec3 uv = (p + 1.0) * 0.5 * dim;
    ivec3 idx = ivec3(clamp(floor(uv), vec3(0.0), dim - 1.0));
    int i = idx.x + idx.y * {resolution} + idx.z * {resolution * resolution};
    return sdfData[i];
}}
"""
    return glsl_code