slice STL to SVG groups

slice.py

import numpy as np
from stl import mesh
import svgwrite

def export_stl_slices_to_svg_with_groups(stl_file, output_svg, num_slices):
    m = mesh.Mesh.from_file(stl_file)
    z_min, z_max = m.z.min(), m.z.max()
    x_min, x_max = m.x.min(), m.x.max()
    y_min, y_max = m.y.min(), m.y.max()
    width = x_max - x_min
    height = y_max - y_min

    slice_heights = np.linspace(z_min, z_max, num_slices)
    dwg = svgwrite.Drawing(
        output_svg,
        profile='tiny',
        size=(width.item(), height.item()),
        viewBox=f"{x_min} {y_min} {width} {height}"
    )
    
    for i, z in enumerate(slice_heights):
        slice_lines = []
        for triangle in m.vectors:
            # Extract vertices
            v1, v2, v3 = triangle
            plane_z = z
            # Check intersections of triangle edges with the slicing plane
            edges = [(v1, v2), (v2, v3), (v3, v1)]
            intersections = []
            for edge in edges:
                p1, p2 = edge
                if (p1[2] < plane_z and p2[2] >= plane_z) or (p1[2] >= plane_z and p2[2] < plane_z):
                    t = (plane_z - p1[2]) / (p2[2] - p1[2])
                    intersection = p1 + t * (p2 - p1)
                    intersections.append(intersection[:2])
            
            if len(intersections) == 2:  # A valid edge is found
                slice_lines.append(intersections)
        
        group = dwg.g(id=f"slice_{i:03d}")
        for line in slice_lines:
            # Convert numpy float32 to Python float
            start = (float(line[0][0]), float(line[0][1]))
            end = (float(line[1][0]), float(line[1][1]))
            group.add(dwg.line(start=start, end=end, stroke=svgwrite.rgb(0, 0, 0, '%')))
        dwg.add(group)
    dwg.save()

stl_file = 'bunny.stl'
output_svg = 'bunny.svg'
num_slices = 30  # Adjust as needed
export_stl_slices_to_svg_with_groups(stl_file, output_svg, num_slices)