test.py

"""
Test script for quad_converter
Reads an OBJ file, converts triangles to quads, and saves the result as a new OBJ file
"""

import quad_converter
import numpy as np
import os


def load_obj(obj_path):
    vertices = []
    faces = []
    
    print(f"[Info] Loading: {obj_path}")
    with open(obj_path, "r", encoding="utf-8") as f:
        for line in f:
            line = line.strip()
            if not line or line.startswith("#"):
                continue
                
            if line.startswith("v "):
                # Vertex: v x y z
                parts = line.split()
                if len(parts) >= 4:
                    x, y, z = float(parts[1]), float(parts[2]), float(parts[3])
                    vertices.append([x, y, z])
                    
            elif line.startswith("f "):
                # Face: f v1 v2 v3 or f v1/vt1/vn1 v2/vt2/vn2 v3/vt3/vn3
                parts = line.split()[1:]
                if len(parts) != 3:
                    print(f"[Warning] Skipping non-triangle face: {line}")
                    continue
                    
                idx = []
                for p in parts:
                    # Handle formats like "1", "1/1", "1/1/1", "1//1"
                    if "/" in p:
                        p = p.split("/")[0]
                    vi = int(p)
                    # OBJ uses 1-based indexing, convert to 0-based
                    if vi < 0:
                        vi = len(vertices) + 1 + vi
                    idx.append(vi - 1)
                faces.append(idx)
    
    V = np.array(vertices, dtype=np.float64)
    F = np.array(faces, dtype=np.int32)
    
    print(f"[Info] Loaded {len(V)} vertices, {len(F)} triangles")
    return V, F


def save_obj(output_path, vertices, quads, tris):
    """Save vertices + quads + triangles to OBJ file"""
    print(f"[Info] Saving to: {output_path}")
    
    with open(output_path, "w", encoding="utf-8") as f:
        f.write("# Quad-dominant mesh generated by quad_converter\n")
        f.write(f"# Vertices: {len(vertices)}\n")
        f.write(f"# Quads: {len(quads)}\n")
        f.write(f"# Triangles: {len(tris)}\n\n")
        
        # Write vertices
        for v in vertices:
            f.write(f"v {v[0]:.9f} {v[1]:.9f} {v[2]:.9f}\n")
        
        f.write("\n")
        
        # Write quad faces (4 vertices)
        for q in quads:
            # Convert 0-based to 1-based indexing
            a, b, c, d = int(q[0]) + 1, int(q[1]) + 1, int(q[2]) + 1, int(q[3]) + 1
            f.write(f"f {a} {b} {c} {d}\n")
        
        # Write triangle faces (3 vertices)
        for t in tris:
            a, b, c = int(t[0]) + 1, int(t[1]) + 1, int(t[2]) + 1
            f.write(f"f {a} {b} {c}\n")
    
    print(f"[OK] Saved successfully!")


def main():
    # write your own input and output paths here!!!
    input_obj = "<your input tri-obj path>"
    output_obj = "<your output quad-dominant obj path>"
    
    vertices, triangles = load_obj(input_obj)
    
    print("\n[Info] Converting triangles to quads...")
    print(f"[Info] Using method: blossom (optimal matching)")
    print(f"[Info] Angle threshold: 150.0 degrees")
    
    result = quad_converter.tri_to_quad(
        vertices,
        triangles,
        angle_threshold_deg=150.0,
        method="blossom",
        verbose=True
    )
    
    new_vertices = result["new_vertices"]
    quad_faces = result["quads"]
    tri_faces = result["tris"]
    stats = result["merge_stats"]
    
    print("\n" + "="*60)
    print("Conversion Results:")
    print("="*60)
    print(f"Generated quads:     {len(quad_faces)}")
    print(f"Remaining triangles: {len(tri_faces)}")
    print(f"Total faces:         {len(quad_faces) + len(tri_faces)}")
    print(f"Vertices:            {len(new_vertices)}")
    
    if stats:
        print("\nDetailed Statistics:")
        for key, value in stats.items():
            print(f"  {key}: {value}")
    
    original_tri_count = len(triangles)
    quad_count = len(quad_faces)
    conversion_rate = (quad_count * 2) / original_tri_count * 100 if original_tri_count > 0 else 0
    print(f"\nConversion rate: {conversion_rate:.1f}% of triangles converted to quads")
    print("="*60 + "\n")
    
    save_obj(output_obj, new_vertices, quad_faces, tri_faces)
    
    print(f"\n✅ Done! Check the output file:")
    print(f"   {output_obj}")


if __name__ == "__main__":
    main()