draco-core 1.0.3

//! Required Rust/C++ interop coverage for Rust-encoded Edgebreaker meshes.

use std::fs;
use std::path::{Path, PathBuf};
use std::process::Command;

use draco_core::decoder_buffer::DecoderBuffer;
use draco_core::draco_types::DataType;
use draco_core::encoder_buffer::EncoderBuffer;
use draco_core::encoder_options::EncoderOptions;
use draco_core::geometry_attribute::{GeometryAttributeType, PointAttribute};
use draco_core::geometry_indices::PointIndex;
use draco_core::mesh::Mesh;
use draco_core::mesh_decoder::MeshDecoder;
use draco_core::mesh_encoder::MeshEncoder;
use draco_core::point_cloud::PointCloud;
use draco_core::point_cloud_decoder::PointCloudDecoder;
use draco_core::point_cloud_encoder::PointCloudEncoder;

const POSITION_TOLERANCE: f32 = 0.01;
const NORMAL_TOLERANCE: f32 = 0.02;
const TEX_COORD_TOLERANCE: f32 = 0.01;

const BUILD_HINT: &str = "C++ Draco tools are required for this test. Build them with: \
cmake -S . -B build -G \"Visual Studio 17 2022\" && \
cmake --build build --config Release --target draco_decoder draco_encoder";

#[derive(Debug, Clone)]
struct VertexRecord {
    position: [f32; 3],
    normal: [f32; 3],
    tex_coord: [f32; 2],
}

#[derive(Debug)]
struct ObjSummary {
    positions: Vec<[f32; 3]>,
    normals: Vec<[f32; 3]>,
    tex_coords: Vec<[f32; 2]>,
    faces: Vec<Vec<String>>,
}

fn repo_root() -> PathBuf {
    PathBuf::from(env!("CARGO_MANIFEST_DIR"))
        .parent()
        .expect("crates directory")
        .parent()
        .expect("repo root")
        .to_path_buf()
}

fn cpp_tool_from_dir(build_dir: &Path, tool_name: &str) -> Option<PathBuf> {
    let direct = build_dir.join(tool_name);
    if direct.exists() {
        return Some(direct);
    }

    for config in ["Release", "Debug"] {
        let configured = build_dir.join(config).join(tool_name);
        if configured.exists() {
            return Some(configured);
        }
    }

    let nested = build_dir.join("src").join("draco");
    for config in ["Release", "Debug"] {
        let configured = nested.join(config).join(tool_name);
        if configured.exists() {
            return Some(configured);
        }
    }

    None
}

fn find_cpp_tool(env_var: &str, tool_name: &str) -> PathBuf {
    if let Ok(path) = std::env::var(env_var) {
        let path = PathBuf::from(path);
        assert!(
            path.exists(),
            "{} points to a missing {}: {}\n{}",
            env_var,
            tool_name,
            path.display(),
            BUILD_HINT
        );
        return path;
    }

    if let Ok(build_dir) = std::env::var("DRACO_CPP_BUILD_DIR") {
        if let Some(path) = cpp_tool_from_dir(Path::new(&build_dir), tool_name) {
            return path;
        }
    }

    let root = repo_root();
    let candidates = [
        root.join("build-original")
            .join("src")
            .join("draco")
            .join("Release")
            .join(tool_name),
        root.join("build")
            .join("src")
            .join("draco")
            .join("Release")
            .join(tool_name),
        root.join("build")
            .join("src")
            .join("draco")
            .join("Debug")
            .join(tool_name),
    ];

    candidates
        .into_iter()
        .find(|path| path.exists())
        .unwrap_or_else(|| panic!("Could not find required C++ tool {tool_name}.\n{BUILD_HINT}"))
}

fn parse_obj(obj_content: &str) -> ObjSummary {
    let mut positions = Vec::new();
    let mut normals = Vec::new();
    let mut tex_coords = Vec::new();
    let mut faces = Vec::new();

    for line in obj_content.lines() {
        let parts: Vec<&str> = line.split_whitespace().collect();
        match parts.as_slice() {
            ["v", x, y, z, ..] => positions.push([
                x.parse().expect("OBJ x position"),
                y.parse().expect("OBJ y position"),
                z.parse().expect("OBJ z position"),
            ]),
            ["vn", x, y, z, ..] => normals.push([
                x.parse().expect("OBJ x normal"),
                y.parse().expect("OBJ y normal"),
                z.parse().expect("OBJ z normal"),
            ]),
            ["vt", u, v, ..] => tex_coords.push([
                u.parse().expect("OBJ u tex coord"),
                v.parse().expect("OBJ v tex coord"),
            ]),
            ["f", indices @ ..] => {
                faces.push(indices.iter().map(|value| value.to_string()).collect())
            }
            _ => {}
        }
    }

    ObjSummary {
        positions,
        normals,
        tex_coords,
        faces,
    }
}

fn write_f32s(attribute: &mut PointAttribute, values: &[f32]) {
    for (i, value) in values.iter().enumerate() {
        attribute.buffer_mut().write(i * 4, &value.to_le_bytes());
    }
}

fn write_u8s(attribute: &mut PointAttribute, values: &[u8]) {
    for (i, value) in values.iter().enumerate() {
        attribute.buffer_mut().write(i, &[*value]);
    }
}

fn read_f32_tuple(attribute: &PointAttribute, point: PointIndex, components: usize) -> Vec<f32> {
    let value_index = attribute.mapped_index(point).0 as usize;
    let offset = value_index * attribute.byte_stride() as usize;
    let data = attribute.buffer().data();
    (0..components)
        .map(|component| {
            let start = offset + component * 4;
            f32::from_le_bytes(data[start..start + 4].try_into().expect("f32 bytes"))
        })
        .collect()
}

fn read_position(attribute: &PointAttribute, point: PointIndex) -> [f32; 3] {
    let values = read_f32_tuple(attribute, point, 3);
    [values[0], values[1], values[2]]
}

fn read_normal(attribute: &PointAttribute, point: PointIndex) -> [f32; 3] {
    let values = read_f32_tuple(attribute, point, 3);
    [values[0], values[1], values[2]]
}

fn read_tex_coord(attribute: &PointAttribute, point: PointIndex) -> [f32; 2] {
    let values = read_f32_tuple(attribute, point, 2);
    [values[0], values[1]]
}

fn close_vec3(a: [f32; 3], b: [f32; 3], tolerance: f32) -> bool {
    (a[0] - b[0]).abs() <= tolerance
        && (a[1] - b[1]).abs() <= tolerance
        && (a[2] - b[2]).abs() <= tolerance
}

fn close_vec2(a: [f32; 2], b: [f32; 2], tolerance: f32) -> bool {
    (a[0] - b[0]).abs() <= tolerance && (a[1] - b[1]).abs() <= tolerance
}

fn build_multi_attribute_mesh() -> (Mesh, Vec<VertexRecord>, usize) {
    let positions: Vec<f32> = vec![
        -1.0, -1.0, 1.0, 1.0, -1.0, 1.0, 1.0, 1.0, 1.0, -1.0, 1.0, 1.0, -1.0, -1.0, -1.0, -1.0,
        1.0, -1.0, 1.0, 1.0, -1.0, 1.0, -1.0, -1.0,
    ];
    let normals: Vec<f32> = vec![
        0.0, 0.0, 1.0, 0.0, 0.0, 1.0, 0.0, 0.0, 1.0, 0.0, 0.0, 1.0, 0.0, 0.0, -1.0, 0.0, 0.0, -1.0,
        0.0, 0.0, -1.0, 0.0, 0.0, -1.0,
    ];
    let tex_coords: Vec<f32> = vec![
        0.0, 0.0, 1.0, 0.0, 1.0, 1.0, 0.0, 1.0, 0.1, 0.2, 0.1, 0.8, 0.9, 0.8, 0.9, 0.2,
    ];
    let colors: Vec<u8> = vec![
        255, 0, 0, 255, 0, 255, 0, 255, 0, 0, 255, 255, 255, 255, 0, 255, 255, 0, 255, 255, 0, 255,
        255, 255, 128, 64, 255, 255, 255, 128, 64, 255,
    ];
    let indices: Vec<u32> = vec![0, 1, 2, 2, 3, 0, 4, 5, 6, 6, 7, 4];

    let vertex_count = positions.len() / 3;
    let face_count = indices.len() / 3;
    let mut mesh = Mesh::new();

    let mut position_attribute = PointAttribute::new();
    position_attribute.init(
        GeometryAttributeType::Position,
        3,
        DataType::Float32,
        false,
        vertex_count,
    );
    write_f32s(&mut position_attribute, &positions);
    mesh.add_attribute(position_attribute);

    let mut normal_attribute = PointAttribute::new();
    normal_attribute.init(
        GeometryAttributeType::Normal,
        3,
        DataType::Float32,
        false,
        vertex_count,
    );
    write_f32s(&mut normal_attribute, &normals);
    mesh.add_attribute(normal_attribute);

    let mut tex_coord_attribute = PointAttribute::new();
    tex_coord_attribute.init(
        GeometryAttributeType::TexCoord,
        2,
        DataType::Float32,
        false,
        vertex_count,
    );
    write_f32s(&mut tex_coord_attribute, &tex_coords);
    mesh.add_attribute(tex_coord_attribute);

    let mut color_attribute = PointAttribute::new();
    color_attribute.init(
        GeometryAttributeType::Color,
        4,
        DataType::Uint8,
        true,
        vertex_count,
    );
    write_u8s(&mut color_attribute, &colors);
    mesh.add_attribute(color_attribute);

    for triangle in indices.chunks_exact(3) {
        mesh.add_face([
            PointIndex(triangle[0]),
            PointIndex(triangle[1]),
            PointIndex(triangle[2]),
        ]);
    }

    let expected_vertices = (0..vertex_count)
        .map(|i| VertexRecord {
            position: [positions[i * 3], positions[i * 3 + 1], positions[i * 3 + 2]],
            normal: [normals[i * 3], normals[i * 3 + 1], normals[i * 3 + 2]],
            tex_coord: [tex_coords[i * 2], tex_coords[i * 2 + 1]],
        })
        .collect();

    (mesh, expected_vertices, face_count)
}

fn build_point_cloud_with_attributes() -> PointCloud {
    let positions: Vec<f32> = vec![
        -1.0, -1.0, 0.0, 0.0, -1.0, 0.5, 1.0, -1.0, 0.0, -0.5, 0.0, 1.0, 0.5, 0.0, 1.0, -1.0, 1.0,
        0.0, 0.0, 1.0, 0.5, 1.0, 1.0, 0.0,
    ];
    let normals: Vec<f32> = vec![
        0.0, 0.0, 1.0, 0.0, 0.0, 1.0, 0.0, 0.0, 1.0, 0.0, 1.0, 0.0, 0.0, 1.0, 0.0, 1.0, 0.0, 0.0,
        1.0, 0.0, 0.0, 1.0, 0.0, 0.0,
    ];
    let colors: Vec<u8> = vec![
        255, 0, 0, 255, 0, 255, 0, 255, 0, 0, 255, 255, 255, 255, 0, 255, 255, 0, 255, 255, 0, 255,
        255, 255, 128, 64, 255, 255, 255, 128, 64, 255,
    ];
    let point_count = positions.len() / 3;
    let mut point_cloud = PointCloud::new();
    point_cloud.set_num_points(point_count);

    let mut position_attribute = PointAttribute::new();
    position_attribute.init(
        GeometryAttributeType::Position,
        3,
        DataType::Float32,
        false,
        point_count,
    );
    write_f32s(&mut position_attribute, &positions);
    point_cloud.add_attribute(position_attribute);

    let mut normal_attribute = PointAttribute::new();
    normal_attribute.init(
        GeometryAttributeType::Normal,
        3,
        DataType::Float32,
        false,
        point_count,
    );
    write_f32s(&mut normal_attribute, &normals);
    point_cloud.add_attribute(normal_attribute);

    let mut color_attribute = PointAttribute::new();
    color_attribute.init(
        GeometryAttributeType::Color,
        4,
        DataType::Uint8,
        true,
        point_count,
    );
    write_u8s(&mut color_attribute, &colors);
    point_cloud.add_attribute(color_attribute);

    point_cloud
}

fn rust_decode_mesh_invariants(bytes: &[u8], expected_method: u8) {
    assert_eq!(&bytes[0..5], b"DRACO");
    assert_eq!(bytes[7], 1, "expected triangular mesh geometry type");
    assert_eq!(bytes[8], expected_method, "unexpected mesh encoding method");

    let mut decoder = MeshDecoder::new();
    let mut mesh = Mesh::new();
    let mut decode_buffer = DecoderBuffer::new(bytes);
    decoder
        .decode(&mut decode_buffer, &mut mesh)
        .expect("Rust decode of Rust mesh stream failed");

    assert!(mesh.num_points() > 0);
    assert!(mesh.num_faces() > 0);
    assert!(mesh.num_attributes() >= 4);
    assert!(mesh.named_attribute_id(GeometryAttributeType::Position) >= 0);
    assert!(mesh.named_attribute_id(GeometryAttributeType::Normal) >= 0);
    assert!(mesh.named_attribute_id(GeometryAttributeType::TexCoord) >= 0);
    assert!(mesh.named_attribute_id(GeometryAttributeType::Color) >= 0);
}

fn rust_decode_point_cloud_invariants(bytes: &[u8]) {
    assert_eq!(&bytes[0..5], b"DRACO");
    assert_eq!(bytes[7], 0, "expected point cloud geometry type");
    assert_eq!(bytes[8], 0, "expected sequential point cloud encoding");

    let mut decoder = PointCloudDecoder::new();
    let mut point_cloud = PointCloud::new();
    let mut decode_buffer = DecoderBuffer::new(bytes);
    decoder
        .decode(&mut decode_buffer, &mut point_cloud)
        .expect("Rust decode of Rust point-cloud stream failed");

    assert!(point_cloud.num_points() > 0);
    assert!(point_cloud.num_attributes() >= 3);
    assert!(point_cloud.named_attribute_id(GeometryAttributeType::Position) >= 0);
    assert!(point_cloud.named_attribute_id(GeometryAttributeType::Normal) >= 0);
    assert!(point_cloud.named_attribute_id(GeometryAttributeType::Color) >= 0);
}

fn run_cpp_decoder(decoder_exe: &Path, drc_path: &Path, out_path: &Path, context: &str) {
    let output = Command::new(decoder_exe)
        .arg("-i")
        .arg(drc_path)
        .arg("-o")
        .arg(out_path)
        .output()
        .expect("run C++ Draco decoder");

    assert!(
        output.status.success(),
        "C++ decoder failed for {context}\nstdout:\n{}\nstderr:\n{}",
        String::from_utf8_lossy(&output.stdout),
        String::from_utf8_lossy(&output.stderr)
    );

    let metadata = fs::metadata(out_path).expect("C++ decoder output missing");
    assert!(metadata.len() > 0, "C++ decoder output is empty");
}

fn decoded_vertex_records(mesh: &Mesh) -> Vec<VertexRecord> {
    let position_id = mesh.named_attribute_id(GeometryAttributeType::Position);
    let normal_id = mesh.named_attribute_id(GeometryAttributeType::Normal);
    let tex_coord_id = mesh.named_attribute_id(GeometryAttributeType::TexCoord);
    assert!(position_id >= 0, "Rust decode missing POSITION attribute");
    assert!(normal_id >= 0, "Rust decode missing NORMAL attribute");
    assert!(tex_coord_id >= 0, "Rust decode missing TEX_COORD attribute");

    let position_attribute = mesh.attribute(position_id);
    let normal_attribute = mesh.attribute(normal_id);
    let tex_coord_attribute = mesh.attribute(tex_coord_id);

    (0..mesh.num_points())
        .map(|point| {
            let point = PointIndex(point as u32);
            VertexRecord {
                position: read_position(position_attribute, point),
                normal: read_normal(normal_attribute, point),
                tex_coord: read_tex_coord(tex_coord_attribute, point),
            }
        })
        .collect()
}

fn assert_vertex_records_match(expected: &[VertexRecord], actual: &[VertexRecord]) {
    assert_eq!(actual.len(), expected.len(), "decoded point count mismatch");
    let mut matched = vec![false; actual.len()];

    for expected_vertex in expected {
        let Some((actual_index, _)) = actual.iter().enumerate().find(|(index, actual_vertex)| {
            !matched[*index]
                && close_vec3(
                    expected_vertex.position,
                    actual_vertex.position,
                    POSITION_TOLERANCE,
                )
                && close_vec3(
                    expected_vertex.normal,
                    actual_vertex.normal,
                    NORMAL_TOLERANCE,
                )
                && close_vec2(
                    expected_vertex.tex_coord,
                    actual_vertex.tex_coord,
                    TEX_COORD_TOLERANCE,
                )
        }) else {
            panic!(
                "No decoded Rust vertex matched expected vertex {:?}\nActual vertices: {:?}",
                expected_vertex, actual
            );
        };
        matched[actual_index] = true;
    }
}

fn assert_position_sets_match(expected: &[[f32; 3]], actual: &[[f32; 3]], context: &str) {
    assert_eq!(
        actual.len(),
        expected.len(),
        "{context} position count mismatch"
    );
    let mut matched = vec![false; actual.len()];

    for &expected_position in expected {
        let Some((actual_index, _)) =
            actual.iter().enumerate().find(|(index, &actual_position)| {
                !matched[*index]
                    && close_vec3(expected_position, actual_position, POSITION_TOLERANCE)
            })
        else {
            panic!(
                "{context}: no decoded position matched expected {:?}\nActual positions: {:?}",
                expected_position, actual
            );
        };
        matched[actual_index] = true;
    }
}

fn assert_vec3_sets_match(
    expected: &[[f32; 3]],
    actual: &[[f32; 3]],
    tolerance: f32,
    context: &str,
) {
    assert_eq!(actual.len(), expected.len(), "{context} count mismatch");
    let mut matched = vec![false; actual.len()];

    for &expected_value in expected {
        let Some((actual_index, _)) = actual.iter().enumerate().find(|(index, &actual_value)| {
            !matched[*index] && close_vec3(expected_value, actual_value, tolerance)
        }) else {
            panic!(
                "{context}: no decoded value matched expected {:?}\nActual values: {:?}",
                expected_value, actual
            );
        };
        matched[actual_index] = true;
    }
}

fn assert_vec2_sets_match(
    expected: &[[f32; 2]],
    actual: &[[f32; 2]],
    tolerance: f32,
    context: &str,
) {
    assert_eq!(actual.len(), expected.len(), "{context} count mismatch");
    let mut matched = vec![false; actual.len()];

    for &expected_value in expected {
        let Some((actual_index, _)) = actual.iter().enumerate().find(|(index, &actual_value)| {
            !matched[*index] && close_vec2(expected_value, actual_value, tolerance)
        }) else {
            panic!(
                "{context}: no decoded value matched expected {:?}\nActual values: {:?}",
                expected_value, actual
            );
        };
        matched[actual_index] = true;
    }
}

#[test]
fn rust_encode_cpp_decode_small_matrix() {
    let decoder_exe = find_cpp_tool("DRACO_CPP_DECODER", "draco_decoder.exe");
    let tmp = std::env::temp_dir().join("draco_rust_encode_cpp_decode_small_matrix");
    fs::create_dir_all(&tmp).expect("create temp dir");

    for (name, encoding_method, encoding_speed) in [
        ("mesh_sequential_pos_norm_uv_color", 0, 10),
        ("mesh_edgebreaker_pos_norm_uv_color", 1, 5),
    ] {
        let (mesh, _expected_vertices, _expected_face_count) = build_multi_attribute_mesh();
        let position_id = mesh.named_attribute_id(GeometryAttributeType::Position);
        let normal_id = mesh.named_attribute_id(GeometryAttributeType::Normal);
        let tex_coord_id = mesh.named_attribute_id(GeometryAttributeType::TexCoord);

        let mut options = EncoderOptions::default();
        options.set_global_int("encoding_method", encoding_method);
        options.set_global_int("encoding_speed", encoding_speed);
        options.set_global_int("decoding_speed", encoding_speed);
        options.set_global_int("split_mesh_on_seams", 0);
        options.set_attribute_int(position_id, "quantization_bits", 14);
        options.set_attribute_int(normal_id, "quantization_bits", 10);
        options.set_attribute_int(tex_coord_id, "quantization_bits", 12);

        let mut encoder = MeshEncoder::new();
        encoder.set_mesh(mesh);
        let mut encoded = EncoderBuffer::new();
        encoder
            .encode(&options, &mut encoded)
            .unwrap_or_else(|err| panic!("Rust mesh encode failed for {name}: {err:?}"));
        let draco_bytes = encoded.data().to_vec();

        rust_decode_mesh_invariants(&draco_bytes, encoding_method as u8);

        let drc_path = tmp.join(format!("{name}.drc"));
        let ply_path = tmp.join(format!("{name}.ply"));
        fs::write(&drc_path, &draco_bytes).expect("write Rust mesh DRC");
        run_cpp_decoder(&decoder_exe, &drc_path, &ply_path, name);
    }

    for (name, prediction_scheme) in [
        ("point_cloud_sequential_pos_norm_color", None),
        (
            "point_cloud_sequential_no_prediction_pos_norm_color",
            Some(-2),
        ),
    ] {
        let point_cloud = build_point_cloud_with_attributes();
        let position_id = point_cloud.named_attribute_id(GeometryAttributeType::Position);
        let normal_id = point_cloud.named_attribute_id(GeometryAttributeType::Normal);

        let mut options = EncoderOptions::default();
        options.set_global_int("encoding_method", 0);
        options.set_global_int("encoding_speed", 5);
        options.set_global_int("decoding_speed", 5);
        options.set_version(2, 3);
        options.set_attribute_int(position_id, "quantization_bits", 14);
        options.set_attribute_int(normal_id, "quantization_bits", 10);
        if let Some(prediction_scheme) = prediction_scheme {
            options.set_prediction_scheme(prediction_scheme);
        }

        let mut encoder = PointCloudEncoder::new();
        encoder.set_point_cloud(point_cloud);
        let mut encoded = EncoderBuffer::new();
        encoder
            .encode(&options, &mut encoded)
            .unwrap_or_else(|err| panic!("Rust point-cloud encode failed for {name}: {err:?}"));
        let draco_bytes = encoded.data().to_vec();

        rust_decode_point_cloud_invariants(&draco_bytes);

        let drc_path = tmp.join(format!("{name}.drc"));
        let ply_path = tmp.join(format!("{name}.ply"));
        fs::write(&drc_path, &draco_bytes).expect("write Rust point-cloud DRC");
        run_cpp_decoder(&decoder_exe, &drc_path, &ply_path, name);
    }
}

#[test]
fn compare_rust_vs_cpp_decode() {
    let decoder_exe = find_cpp_tool("DRACO_CPP_DECODER", "draco_decoder.exe");
    let encoder_exe = find_cpp_tool("DRACO_CPP_ENCODER", "draco_encoder.exe");
    assert!(
        encoder_exe.exists(),
        "Required C++ encoder is missing: {}\n{}",
        encoder_exe.display(),
        BUILD_HINT
    );

    let (mesh, expected_vertices, expected_face_count) = build_multi_attribute_mesh();

    let position_id = mesh.named_attribute_id(GeometryAttributeType::Position);
    let normal_id = mesh.named_attribute_id(GeometryAttributeType::Normal);
    let tex_coord_id = mesh.named_attribute_id(GeometryAttributeType::TexCoord);

    let mut options = EncoderOptions::default();
    options.set_global_int("encoding_method", 1);
    options.set_global_int("encoding_speed", 5);
    options.set_global_int("decoding_speed", 5);
    options.set_global_int("split_mesh_on_seams", 0);
    options.set_attribute_int(position_id, "quantization_bits", 14);
    options.set_attribute_int(normal_id, "quantization_bits", 10);
    options.set_attribute_int(tex_coord_id, "quantization_bits", 12);

    let mut encoder = MeshEncoder::new();
    encoder.set_mesh(mesh);
    let mut encoded = EncoderBuffer::new();
    encoder
        .encode(&options, &mut encoded)
        .expect("Rust Edgebreaker encode failed");
    let draco_bytes = encoded.data().to_vec();

    assert_eq!(&draco_bytes[0..5], b"DRACO");
    assert_eq!(draco_bytes[7], 1, "expected triangular mesh geometry type");
    assert_eq!(draco_bytes[8], 1, "expected Rust Edgebreaker encoding");

    let mut rust_decoder = MeshDecoder::new();
    let mut rust_mesh = Mesh::new();
    let mut decode_buffer = DecoderBuffer::new(&draco_bytes);
    rust_decoder
        .decode(&mut decode_buffer, &mut rust_mesh)
        .expect("Rust decode of Rust Edgebreaker stream failed");

    assert_eq!(
        rust_mesh.num_faces(),
        expected_face_count,
        "Rust decoded face count mismatch"
    );
    let rust_vertices = decoded_vertex_records(&rust_mesh);

    let tmp = std::env::temp_dir().join("draco_edgebreaker_multi_attribute_cpp_required");
    fs::create_dir_all(&tmp).expect("create temp dir");
    let drc_path = tmp.join("multi_attr_edgebreaker.drc");
    let obj_path = tmp.join("multi_attr_edgebreaker.obj");
    fs::write(&drc_path, &draco_bytes).expect("write Rust Edgebreaker DRC");

    let output = Command::new(&decoder_exe)
        .arg("-i")
        .arg(&drc_path)
        .arg("-o")
        .arg(&obj_path)
        .output()
        .expect("run C++ Draco decoder");

    assert!(
        output.status.success(),
        "C++ decoder failed for Rust Edgebreaker multi-attribute stream\nstdout:\n{}\nstderr:\n{}",
        String::from_utf8_lossy(&output.stdout),
        String::from_utf8_lossy(&output.stderr)
    );

    let obj_content = fs::read_to_string(&obj_path).expect("read C++ decoded OBJ");
    let obj = parse_obj(&obj_content);
    let expected_positions: Vec<[f32; 3]> = expected_vertices
        .iter()
        .map(|vertex| vertex.position)
        .collect();
    let expected_normals: Vec<[f32; 3]> = expected_vertices
        .iter()
        .map(|vertex| vertex.normal)
        .collect();
    let expected_tex_coords: Vec<[f32; 2]> = expected_vertices
        .iter()
        .map(|vertex| vertex.tex_coord)
        .collect();
    let rust_positions: Vec<[f32; 3]> =
        rust_vertices.iter().map(|vertex| vertex.position).collect();
    let rust_normals: Vec<[f32; 3]> = rust_vertices.iter().map(|vertex| vertex.normal).collect();
    let rust_tex_coords: Vec<[f32; 2]> = rust_vertices
        .iter()
        .map(|vertex| vertex.tex_coord)
        .collect();

    assert_position_sets_match(&rust_positions, &obj.positions, "C++ vs Rust");
    assert_position_sets_match(&expected_positions, &obj.positions, "C++ vs expected");
    assert_vec3_sets_match(
        &rust_normals,
        &obj.normals,
        NORMAL_TOLERANCE,
        "C++ vs Rust normals",
    );
    assert_vec3_sets_match(
        &expected_normals,
        &obj.normals,
        NORMAL_TOLERANCE,
        "C++ vs expected normals",
    );
    assert_vec2_sets_match(
        &rust_tex_coords,
        &obj.tex_coords,
        TEX_COORD_TOLERANCE,
        "C++ vs Rust tex coords",
    );
    assert_vec2_sets_match(
        &expected_tex_coords,
        &obj.tex_coords,
        TEX_COORD_TOLERANCE,
        "C++ vs expected tex coords",
    );
    assert_eq!(
        obj.faces.len(),
        expected_face_count,
        "C++ decoded OBJ face count mismatch"
    );

    assert_vertex_records_match(&expected_vertices, &rust_vertices);
}