draco-io 0.3.2

use draco_core::decoder_buffer::DecoderBuffer;
use draco_core::geometry_attribute::GeometryAttributeType;
use draco_core::mesh::Mesh;
use draco_core::mesh_decoder::MeshDecoder;
use std::path::Path;

fn main() {
    // The file to decode comes from the caller. The default used to be one
    // machine's C++ Draco output directory, which worked nowhere else.
    let args: Vec<String> = std::env::args().collect();
    let Some(path) = args.get(1) else {
        eprintln!("usage: cargo run --example decode_drc -- <file.drc>");
        std::process::exit(2);
    };
    let test_file = Path::new(path).to_path_buf();

    let data = std::fs::read(&test_file).expect("Failed to read file");
    let mut decoder = MeshDecoder::new();
    let mut buffer = DecoderBuffer::new(&data);
    let mut mesh = Mesh::new();

    decoder
        .decode(&mut buffer, &mut mesh)
        .expect("Failed to decode");

    println!(
        "Decoded mesh: {} faces, {} points, {} attrs",
        mesh.num_faces(),
        mesh.num_points(),
        mesh.num_attributes()
    );

    // Find position attribute and compute bounds
    let pos_id = mesh.named_attribute_id(GeometryAttributeType::Position);
    if pos_id >= 0 {
        let pos_attr = mesh.attribute(pos_id);
        let buffer = pos_attr.buffer();
        let num_components = pos_attr.num_components() as usize;
        let byte_stride = pos_attr.byte_stride() as usize;

        let mut min_vals = [f32::MAX; 3];
        let mut max_vals = [f32::MIN; 3];

        for i in 0..pos_attr.size() {
            let offset = i * byte_stride;
            for c in 0..num_components.min(3) {
                let bytes: [u8; 4] = buffer.data()[offset + c * 4..offset + c * 4 + 4]
                    .try_into()
                    .unwrap();
                let val = f32::from_le_bytes(bytes);
                if val < min_vals[c] {
                    min_vals[c] = val;
                }
                if val > max_vals[c] {
                    max_vals[c] = val;
                }
            }
        }

        println!("Position bounds:");
        println!("  X: {} to {}", min_vals[0], max_vals[0]);
        println!("  Y: {} to {}", min_vals[1], max_vals[1]);
        println!("  Z: {} to {}", min_vals[2], max_vals[2]);
    }
}