occt_wasm/

kernel.rs

//! WASM host implementation for the OCCT kernel.
//!
//! Manages the wasmtime `Engine`, `Store`, and `Instance`, and provides
//! helper methods for memory transfer across the WASM boundary.

use wasmtime::{Engine, Instance, Linker, Memory, Module, Store, TypedFunc};

use crate::error::{OcctError, OcctResult};
use crate::kernel_generated::GeneratedFuncs;
use crate::types::{
    BoundingBox, EdgeData, EvolutionData, LabelInfo, Mesh, MeshBatch, NurbsCurveData,
    ProjectionData, ShapeHandle, Vec3,
};

/// Brotli-compressed WASM binary, embedded at compile time.
///
/// The uncompressed binary is ~21 MB; brotli brings it to ~4 MB.
/// This is decompressed once during `OcctKernel::new()`.
static WASM_BINARY: &[u8] = include_bytes!("occt-wasm.wasm.br");

/// The OCCT CAD kernel, backed by a sandboxed WASM module.
///
/// Create an instance with [`OcctKernel::new()`], then call methods to
/// create and manipulate shapes. All shapes live in an arena inside the
/// WASM module and are referenced by [`ShapeHandle`].
///
/// # Example
///
/// ```no_run
/// use occt_wasm::{OcctKernel, ShapeHandle};
///
/// let mut kernel = OcctKernel::new().unwrap();
/// let box_shape = kernel.make_box(10.0, 20.0, 30.0).unwrap();
/// let volume = kernel.get_volume(box_shape).unwrap();
/// assert!((volume - 6000.0).abs() < 1.0);
/// ```
pub struct OcctKernel {
    pub(crate) store: Store<()>,
    pub(crate) instance: Instance,
    pub(crate) memory: Memory,

    // Lifecycle + error functions
    pub(crate) fn_has_error: TypedFunc<(), i32>,
    pub(crate) fn_get_error: TypedFunc<(), i32>,
    pub(crate) fn_get_error_len: TypedFunc<(), u32>,

    // Memory management
    pub(crate) fn_alloc: TypedFunc<u32, u32>,
    pub(crate) fn_free: TypedFunc<u32, ()>,

    // Result buffer accessors
    pub(crate) fn_get_string_result: TypedFunc<(), i32>,
    pub(crate) fn_get_string_result_len: TypedFunc<(), u32>,
    pub(crate) fn_get_vec_u32_result: TypedFunc<(), i32>,
    pub(crate) fn_get_vec_u32_result_len: TypedFunc<(), u32>,
    pub(crate) fn_get_vec_f64_result: TypedFunc<(), i32>,
    pub(crate) fn_get_vec_f64_result_len: TypedFunc<(), u32>,
    pub(crate) fn_get_vec_i32_result: TypedFunc<(), i32>,
    pub(crate) fn_get_vec_i32_result_len: TypedFunc<(), u32>,

    // BBox accessors
    pub(crate) fn_get_bbox_xmin: TypedFunc<(), f64>,
    pub(crate) fn_get_bbox_ymin: TypedFunc<(), f64>,
    pub(crate) fn_get_bbox_zmin: TypedFunc<(), f64>,
    pub(crate) fn_get_bbox_xmax: TypedFunc<(), f64>,
    pub(crate) fn_get_bbox_ymax: TypedFunc<(), f64>,
    pub(crate) fn_get_bbox_zmax: TypedFunc<(), f64>,

    // Mesh accessors
    pub(crate) fn_get_mesh_positions: TypedFunc<(), i32>,
    pub(crate) fn_get_mesh_positions_len: TypedFunc<(), i32>,
    pub(crate) fn_get_mesh_normals: TypedFunc<(), i32>,
    pub(crate) fn_get_mesh_normals_len: TypedFunc<(), i32>,
    pub(crate) fn_get_mesh_indices: TypedFunc<(), i32>,
    pub(crate) fn_get_mesh_indices_len: TypedFunc<(), i32>,
    pub(crate) fn_get_mesh_face_groups: TypedFunc<(), i32>,
    pub(crate) fn_get_mesh_face_groups_len: TypedFunc<(), i32>,

    // MeshBatch accessors
    pub(crate) fn_get_mesh_batch_positions: TypedFunc<(), i32>,
    pub(crate) fn_get_mesh_batch_positions_len: TypedFunc<(), i32>,
    pub(crate) fn_get_mesh_batch_normals: TypedFunc<(), i32>,
    pub(crate) fn_get_mesh_batch_normals_len: TypedFunc<(), i32>,
    pub(crate) fn_get_mesh_batch_indices: TypedFunc<(), i32>,
    pub(crate) fn_get_mesh_batch_indices_len: TypedFunc<(), i32>,
    pub(crate) fn_get_mesh_batch_shape_offsets: TypedFunc<(), i32>,
    pub(crate) fn_get_mesh_batch_shape_count: TypedFunc<(), i32>,

    // Edge accessors
    pub(crate) fn_get_edge_points: TypedFunc<(), i32>,
    pub(crate) fn_get_edge_points_len: TypedFunc<(), i32>,
    pub(crate) fn_get_edge_groups: TypedFunc<(), i32>,
    pub(crate) fn_get_edge_groups_len: TypedFunc<(), i32>,

    // NURBS accessors
    pub(crate) fn_get_nurbs_degree: TypedFunc<(), i32>,
    pub(crate) fn_get_nurbs_rational: TypedFunc<(), i32>,
    pub(crate) fn_get_nurbs_periodic: TypedFunc<(), i32>,
    pub(crate) fn_get_nurbs_knots: TypedFunc<(), i32>,
    pub(crate) fn_get_nurbs_knots_len: TypedFunc<(), u32>,
    pub(crate) fn_get_nurbs_multiplicities: TypedFunc<(), i32>,
    pub(crate) fn_get_nurbs_multiplicities_len: TypedFunc<(), u32>,
    pub(crate) fn_get_nurbs_poles: TypedFunc<(), i32>,
    pub(crate) fn_get_nurbs_poles_len: TypedFunc<(), u32>,
    pub(crate) fn_get_nurbs_weights: TypedFunc<(), i32>,
    pub(crate) fn_get_nurbs_weights_len: TypedFunc<(), u32>,

    // Evolution accessors
    pub(crate) fn_get_evo_result_id: TypedFunc<(), u32>,
    pub(crate) fn_get_evo_modified: TypedFunc<(), i32>,
    pub(crate) fn_get_evo_modified_len: TypedFunc<(), u32>,
    pub(crate) fn_get_evo_generated: TypedFunc<(), i32>,
    pub(crate) fn_get_evo_generated_len: TypedFunc<(), u32>,
    pub(crate) fn_get_evo_deleted: TypedFunc<(), i32>,
    pub(crate) fn_get_evo_deleted_len: TypedFunc<(), u32>,

    // Projection accessors
    pub(crate) fn_get_proj_visible_outline: TypedFunc<(), u32>,
    pub(crate) fn_get_proj_visible_smooth: TypedFunc<(), u32>,
    pub(crate) fn_get_proj_visible_sharp: TypedFunc<(), u32>,
    pub(crate) fn_get_proj_hidden_outline: TypedFunc<(), u32>,
    pub(crate) fn_get_proj_hidden_smooth: TypedFunc<(), u32>,
    pub(crate) fn_get_proj_hidden_sharp: TypedFunc<(), u32>,

    // Label info accessors
    pub(crate) fn_get_label_info_label_id: TypedFunc<(), i32>,
    pub(crate) fn_get_label_info_name: TypedFunc<(), i32>,
    pub(crate) fn_get_label_info_name_len: TypedFunc<(), u32>,
    pub(crate) fn_get_label_info_has_color: TypedFunc<(), i32>,
    pub(crate) fn_get_label_info_r: TypedFunc<(), f64>,
    pub(crate) fn_get_label_info_g: TypedFunc<(), f64>,
    pub(crate) fn_get_label_info_b: TypedFunc<(), f64>,
    pub(crate) fn_get_label_info_is_assembly: TypedFunc<(), i32>,
    pub(crate) fn_get_label_info_is_component: TypedFunc<(), i32>,
    pub(crate) fn_get_label_info_shape_id: TypedFunc<(), u32>,

    // Generated method handles
    pub(crate) generated: GeneratedFuncs,
}

impl OcctKernel {
    /// Create a new OCCT kernel instance.
    ///
    /// Decompresses the embedded WASM binary, compiles it with `wasmtime`,
    /// and initializes the OCCT runtime. This takes ~100-500ms depending
    /// on the platform.
    #[allow(clippy::too_many_lines)]
    pub fn new() -> OcctResult<Self> {
        let mut config = wasmtime::Config::new();
        config.wasm_simd(true);
        config.wasm_tail_call(true);
        config.wasm_relaxed_simd(true);
        // The WASM binary uses wasm-opt --experimental-new-eh to convert
        // Emscripten's legacy exceptions to the new (exnref) encoding.
        config.wasm_exceptions(true);

        let engine = Engine::new(&config)?;
        let wasm_bytes = decompress_wasm()?;
        let module = Module::new(&engine, &wasm_bytes)?;
        let mut store = Store::new(&engine, ());
        let linker = Linker::new(&engine);
        let instance = linker.instantiate(&mut store, &module)?;

        let memory = instance
            .get_memory(&mut store, "memory")
            .ok_or_else(|| OcctError::Memory("no memory export".to_owned()))?;

        // Call occt_init
        let init: TypedFunc<(), i32> = instance.get_typed_func(&mut store, "occt_init")?;
        let result = init.call(&mut store, ())?;
        if result != 0 {
            return Err(OcctError::Memory("occt_init failed".to_owned()));
        }

        // Resolve all accessor functions
        macro_rules! get_fn {
            ($name:expr => $ret:ty) => {
                instance.get_typed_func::<(), $ret>(&mut store, $name)?
            };
            ($name:expr, $param:ty => $ret:ty) => {
                instance.get_typed_func::<$param, $ret>(&mut store, $name)?
            };
        }

        let generated = GeneratedFuncs::resolve(&instance, &mut store)?;

        Ok(Self {
            memory,
            instance,

            fn_has_error: get_fn!("occt_has_error" => i32),
            fn_get_error: get_fn!("occt_get_error" => i32),
            fn_get_error_len: get_fn!("occt_get_error_len" => u32),
            fn_alloc: get_fn!("occt_alloc", u32 => u32),
            fn_free: get_fn!("occt_free", u32 => ()),

            fn_get_string_result: get_fn!("occt_get_string_result" => i32),
            fn_get_string_result_len: get_fn!("occt_get_string_result_len" => u32),
            fn_get_vec_u32_result: get_fn!("occt_get_vec_u32_result" => i32),
            fn_get_vec_u32_result_len: get_fn!("occt_get_vec_u32_result_len" => u32),
            fn_get_vec_f64_result: get_fn!("occt_get_vec_f64_result" => i32),
            fn_get_vec_f64_result_len: get_fn!("occt_get_vec_f64_result_len" => u32),
            fn_get_vec_i32_result: get_fn!("occt_get_vec_i32_result" => i32),
            fn_get_vec_i32_result_len: get_fn!("occt_get_vec_i32_result_len" => u32),

            fn_get_bbox_xmin: get_fn!("occt_get_bbox_xmin" => f64),
            fn_get_bbox_ymin: get_fn!("occt_get_bbox_ymin" => f64),
            fn_get_bbox_zmin: get_fn!("occt_get_bbox_zmin" => f64),
            fn_get_bbox_xmax: get_fn!("occt_get_bbox_xmax" => f64),
            fn_get_bbox_ymax: get_fn!("occt_get_bbox_ymax" => f64),
            fn_get_bbox_zmax: get_fn!("occt_get_bbox_zmax" => f64),

            fn_get_mesh_positions: get_fn!("occt_get_mesh_positions" => i32),
            fn_get_mesh_positions_len: get_fn!("occt_get_mesh_positions_len" => i32),
            fn_get_mesh_normals: get_fn!("occt_get_mesh_normals" => i32),
            fn_get_mesh_normals_len: get_fn!("occt_get_mesh_normals_len" => i32),
            fn_get_mesh_indices: get_fn!("occt_get_mesh_indices" => i32),
            fn_get_mesh_indices_len: get_fn!("occt_get_mesh_indices_len" => i32),
            fn_get_mesh_face_groups: get_fn!("occt_get_mesh_face_groups" => i32),
            fn_get_mesh_face_groups_len: get_fn!("occt_get_mesh_face_groups_len" => i32),

            fn_get_mesh_batch_positions: get_fn!("occt_get_mesh_batch_positions" => i32),
            fn_get_mesh_batch_positions_len: get_fn!("occt_get_mesh_batch_positions_len" => i32),
            fn_get_mesh_batch_normals: get_fn!("occt_get_mesh_batch_normals" => i32),
            fn_get_mesh_batch_normals_len: get_fn!("occt_get_mesh_batch_normals_len" => i32),
            fn_get_mesh_batch_indices: get_fn!("occt_get_mesh_batch_indices" => i32),
            fn_get_mesh_batch_indices_len: get_fn!("occt_get_mesh_batch_indices_len" => i32),
            fn_get_mesh_batch_shape_offsets: get_fn!("occt_get_mesh_batch_shape_offsets" => i32),
            fn_get_mesh_batch_shape_count: get_fn!("occt_get_mesh_batch_shape_count" => i32),

            fn_get_edge_points: get_fn!("occt_get_edge_points" => i32),
            fn_get_edge_points_len: get_fn!("occt_get_edge_points_len" => i32),
            fn_get_edge_groups: get_fn!("occt_get_edge_groups" => i32),
            fn_get_edge_groups_len: get_fn!("occt_get_edge_groups_len" => i32),

            fn_get_nurbs_degree: get_fn!("occt_get_nurbs_degree" => i32),
            fn_get_nurbs_rational: get_fn!("occt_get_nurbs_rational" => i32),
            fn_get_nurbs_periodic: get_fn!("occt_get_nurbs_periodic" => i32),
            fn_get_nurbs_knots: get_fn!("occt_get_nurbs_knots" => i32),
            fn_get_nurbs_knots_len: get_fn!("occt_get_nurbs_knots_len" => u32),
            fn_get_nurbs_multiplicities: get_fn!("occt_get_nurbs_multiplicities" => i32),
            fn_get_nurbs_multiplicities_len: get_fn!("occt_get_nurbs_multiplicities_len" => u32),
            fn_get_nurbs_poles: get_fn!("occt_get_nurbs_poles" => i32),
            fn_get_nurbs_poles_len: get_fn!("occt_get_nurbs_poles_len" => u32),
            fn_get_nurbs_weights: get_fn!("occt_get_nurbs_weights" => i32),
            fn_get_nurbs_weights_len: get_fn!("occt_get_nurbs_weights_len" => u32),

            fn_get_evo_result_id: get_fn!("occt_get_evo_result_id" => u32),
            fn_get_evo_modified: get_fn!("occt_get_evo_modified" => i32),
            fn_get_evo_modified_len: get_fn!("occt_get_evo_modified_len" => u32),
            fn_get_evo_generated: get_fn!("occt_get_evo_generated" => i32),
            fn_get_evo_generated_len: get_fn!("occt_get_evo_generated_len" => u32),
            fn_get_evo_deleted: get_fn!("occt_get_evo_deleted" => i32),
            fn_get_evo_deleted_len: get_fn!("occt_get_evo_deleted_len" => u32),

            fn_get_proj_visible_outline: get_fn!("occt_get_proj_visible_outline" => u32),
            fn_get_proj_visible_smooth: get_fn!("occt_get_proj_visible_smooth" => u32),
            fn_get_proj_visible_sharp: get_fn!("occt_get_proj_visible_sharp" => u32),
            fn_get_proj_hidden_outline: get_fn!("occt_get_proj_hidden_outline" => u32),
            fn_get_proj_hidden_smooth: get_fn!("occt_get_proj_hidden_smooth" => u32),
            fn_get_proj_hidden_sharp: get_fn!("occt_get_proj_hidden_sharp" => u32),

            fn_get_label_info_label_id: get_fn!("occt_get_label_info_label_id" => i32),
            fn_get_label_info_name: get_fn!("occt_get_label_info_name" => i32),
            fn_get_label_info_name_len: get_fn!("occt_get_label_info_name_len" => u32),
            fn_get_label_info_has_color: get_fn!("occt_get_label_info_has_color" => i32),
            fn_get_label_info_r: get_fn!("occt_get_label_info_r" => f64),
            fn_get_label_info_g: get_fn!("occt_get_label_info_g" => f64),
            fn_get_label_info_b: get_fn!("occt_get_label_info_b" => f64),
            fn_get_label_info_is_assembly: get_fn!("occt_get_label_info_is_assembly" => i32),
            fn_get_label_info_is_component: get_fn!("occt_get_label_info_is_component" => i32),
            fn_get_label_info_shape_id: get_fn!("occt_get_label_info_shape_id" => u32),

            generated,
            store,
        })
    }

    // === Memory helpers ===

    /// Write bytes into WASM linear memory via `occt_alloc`.
    pub(crate) fn write_bytes(&mut self, data: &[u8]) -> OcctResult<u32> {
        let ptr = self.fn_alloc.call(&mut self.store, data.len() as u32)?;
        if ptr == 0 {
            core::hint::cold_path();
            return Err(OcctError::Memory("allocation failed".to_owned()));
        }
        let mem = self.memory.data_mut(&mut self.store);
        let start = ptr as usize;
        let end = start + data.len();
        if end > mem.len() {
            core::hint::cold_path();
            return Err(OcctError::Memory("write out of bounds".to_owned()));
        }
        mem[start..end].copy_from_slice(data);
        Ok(ptr)
    }

    /// Free previously allocated WASM memory.
    pub(crate) fn free_bytes(&mut self, ptr: u32) -> OcctResult<()> {
        self.fn_free.call(&mut self.store, ptr)?;
        Ok(())
    }

    /// Read a byte slice from WASM memory.
    fn read_bytes(&self, ptr: u32, len: u32) -> OcctResult<Vec<u8>> {
        let mem = self.memory.data(&self.store);
        let start = ptr as usize;
        let end = start + len as usize;
        if end > mem.len() {
            core::hint::cold_path();
            return Err(OcctError::Memory("read out of bounds".to_owned()));
        }
        Ok(mem[start..end].to_vec())
    }

    /// Read a typed slice from WASM memory as `f32` values.
    fn read_f32_slice(&self, ptr: u32, count: u32) -> OcctResult<Vec<f32>> {
        let bytes = self.read_bytes(ptr, count * 4)?;
        Ok(bytes
            .chunks_exact(4)
            .map(|c| f32::from_le_bytes([c[0], c[1], c[2], c[3]]))
            .collect())
    }

    /// Read a typed slice from WASM memory as `u32` values.
    fn read_u32_slice(&self, ptr: u32, count: u32) -> OcctResult<Vec<u32>> {
        let bytes = self.read_bytes(ptr, count * 4)?;
        Ok(bytes
            .chunks_exact(4)
            .map(|c| u32::from_le_bytes([c[0], c[1], c[2], c[3]]))
            .collect())
    }

    /// Read a typed slice from WASM memory as `i32` values.
    fn read_i32_slice(&self, ptr: u32, count: u32) -> OcctResult<Vec<i32>> {
        let bytes = self.read_bytes(ptr, count * 4)?;
        Ok(bytes
            .chunks_exact(4)
            .map(|c| i32::from_le_bytes([c[0], c[1], c[2], c[3]]))
            .collect())
    }

    /// Read a typed slice from WASM memory as `f64` values.
    fn read_f64_slice(&self, ptr: u32, count: u32) -> OcctResult<Vec<f64>> {
        let bytes = self.read_bytes(ptr, count * 8)?;
        Ok(bytes
            .chunks_exact(8)
            .map(|c| f64::from_le_bytes([c[0], c[1], c[2], c[3], c[4], c[5], c[6], c[7]]))
            .collect())
    }

    // === Error handling ===

    /// Check if the WASM module has a pending error and return it.
    pub(crate) fn check_error(&mut self, operation: &str) -> OcctResult<()> {
        let has_error = self.fn_has_error.call(&mut self.store, ())?;
        if has_error != 0 {
            // Errors are the exception, not the norm — this branch runs after
            // every facade call. Hint to LLVM that it's cold so the happy path
            // stays tight in the instruction cache. (stabilized in Rust 1.95)
            core::hint::cold_path();
            return Err(self.read_last_error(operation));
        }
        Ok(())
    }

    /// Read the last error message from the WASM module.
    #[cold]
    pub(crate) fn read_last_error(&mut self, operation: &str) -> OcctError {
        let ptr = self.fn_get_error.call(&mut self.store, ()).unwrap_or(0);
        let len = self.fn_get_error_len.call(&mut self.store, ()).unwrap_or(0);
        let message = if ptr != 0 && len > 0 {
            self.read_bytes(ptr as u32, len)
                .ok()
                .and_then(|b| String::from_utf8(b).ok())
                .unwrap_or_else(|| "unknown error".to_owned())
        } else {
            "unknown error".to_owned()
        };
        OcctError::Operation {
            operation: operation.to_owned(),
            message,
        }
    }

    // === Result buffer readers ===

    /// Read a string result from the WASM string buffer.
    pub(crate) fn read_string_result(&mut self) -> OcctResult<String> {
        let ptr = self.fn_get_string_result.call(&mut self.store, ())?;
        let len = self.fn_get_string_result_len.call(&mut self.store, ())?;
        let bytes = self.read_bytes(ptr as u32, len)?;
        String::from_utf8(bytes).map_err(|e| OcctError::Memory(e.to_string()))
    }

    /// Read a `Vec<u32>` result.
    pub(crate) fn read_vec_u32_result(&mut self) -> OcctResult<Vec<u32>> {
        let ptr = self.fn_get_vec_u32_result.call(&mut self.store, ())?;
        let len = self.fn_get_vec_u32_result_len.call(&mut self.store, ())?;
        self.read_u32_slice(ptr as u32, len)
    }

    /// Read a `Vec<f64>` result.
    pub(crate) fn read_vec_f64_result(&mut self) -> OcctResult<Vec<f64>> {
        let ptr = self.fn_get_vec_f64_result.call(&mut self.store, ())?;
        let len = self.fn_get_vec_f64_result_len.call(&mut self.store, ())?;
        self.read_f64_slice(ptr as u32, len)
    }

    /// Read a `Vec<i32>` result.
    pub(crate) fn read_vec_i32_result(&mut self) -> OcctResult<Vec<i32>> {
        let ptr = self.fn_get_vec_i32_result.call(&mut self.store, ())?;
        let len = self.fn_get_vec_i32_result_len.call(&mut self.store, ())?;
        self.read_i32_slice(ptr as u32, len)
    }

    /// Read a bounding box result.
    pub(crate) fn read_bbox_result(&mut self) -> OcctResult<BoundingBox> {
        Ok(BoundingBox {
            min: Vec3 {
                x: self.fn_get_bbox_xmin.call(&mut self.store, ())?,
                y: self.fn_get_bbox_ymin.call(&mut self.store, ())?,
                z: self.fn_get_bbox_zmin.call(&mut self.store, ())?,
            },
            max: Vec3 {
                x: self.fn_get_bbox_xmax.call(&mut self.store, ())?,
                y: self.fn_get_bbox_ymax.call(&mut self.store, ())?,
                z: self.fn_get_bbox_zmax.call(&mut self.store, ())?,
            },
        })
    }

    /// Read a mesh result.
    pub(crate) fn read_mesh_result(&mut self) -> OcctResult<Mesh> {
        let pos_ptr = self.fn_get_mesh_positions.call(&mut self.store, ())?;
        let pos_len = self.fn_get_mesh_positions_len.call(&mut self.store, ())?;
        let norm_ptr = self.fn_get_mesh_normals.call(&mut self.store, ())?;
        let norm_len = self.fn_get_mesh_normals_len.call(&mut self.store, ())?;
        let idx_ptr = self.fn_get_mesh_indices.call(&mut self.store, ())?;
        let idx_len = self.fn_get_mesh_indices_len.call(&mut self.store, ())?;
        let fg_ptr = self.fn_get_mesh_face_groups.call(&mut self.store, ())?;
        let fg_len = self.fn_get_mesh_face_groups_len.call(&mut self.store, ())?;

        Ok(Mesh {
            positions: self.read_f32_slice(pos_ptr as u32, pos_len as u32)?,
            normals: self.read_f32_slice(norm_ptr as u32, norm_len as u32)?,
            indices: self.read_u32_slice(idx_ptr as u32, idx_len as u32)?,
            face_groups: self.read_i32_slice(fg_ptr as u32, fg_len as u32)?,
        })
    }

    /// Read a mesh batch result.
    pub(crate) fn read_mesh_batch_result(&mut self) -> OcctResult<MeshBatch> {
        let pos_ptr = self.fn_get_mesh_batch_positions.call(&mut self.store, ())?;
        let pos_len = self
            .fn_get_mesh_batch_positions_len
            .call(&mut self.store, ())?;
        let norm_ptr = self.fn_get_mesh_batch_normals.call(&mut self.store, ())?;
        let norm_len = self
            .fn_get_mesh_batch_normals_len
            .call(&mut self.store, ())?;
        let idx_ptr = self.fn_get_mesh_batch_indices.call(&mut self.store, ())?;
        let idx_len = self
            .fn_get_mesh_batch_indices_len
            .call(&mut self.store, ())?;
        let off_ptr = self
            .fn_get_mesh_batch_shape_offsets
            .call(&mut self.store, ())?;
        let shape_count = self
            .fn_get_mesh_batch_shape_count
            .call(&mut self.store, ())?;

        Ok(MeshBatch {
            positions: self.read_f32_slice(pos_ptr as u32, pos_len as u32)?,
            normals: self.read_f32_slice(norm_ptr as u32, norm_len as u32)?,
            indices: self.read_u32_slice(idx_ptr as u32, idx_len as u32)?,
            shape_offsets: self.read_i32_slice(off_ptr as u32, (shape_count * 4) as u32)?,
        })
    }

    /// Read an edge data result.
    pub(crate) fn read_edge_result(&mut self) -> OcctResult<EdgeData> {
        let pts_ptr = self.fn_get_edge_points.call(&mut self.store, ())?;
        let pts_len = self.fn_get_edge_points_len.call(&mut self.store, ())?;
        let grp_ptr = self.fn_get_edge_groups.call(&mut self.store, ())?;
        let grp_len = self.fn_get_edge_groups_len.call(&mut self.store, ())?;

        Ok(EdgeData {
            points: self.read_f32_slice(pts_ptr as u32, pts_len as u32)?,
            edge_groups: self.read_i32_slice(grp_ptr as u32, grp_len as u32)?,
        })
    }

    /// Read a NURBS curve data result.
    pub(crate) fn read_nurbs_result(&mut self) -> OcctResult<NurbsCurveData> {
        let degree = self.fn_get_nurbs_degree.call(&mut self.store, ())?;
        let rational = self.fn_get_nurbs_rational.call(&mut self.store, ())? != 0;
        let periodic = self.fn_get_nurbs_periodic.call(&mut self.store, ())? != 0;

        let knots_ptr = self.fn_get_nurbs_knots.call(&mut self.store, ())?;
        let knots_len = self.fn_get_nurbs_knots_len.call(&mut self.store, ())?;
        let mult_ptr = self.fn_get_nurbs_multiplicities.call(&mut self.store, ())?;
        let mult_len = self
            .fn_get_nurbs_multiplicities_len
            .call(&mut self.store, ())?;
        let poles_ptr = self.fn_get_nurbs_poles.call(&mut self.store, ())?;
        let poles_len = self.fn_get_nurbs_poles_len.call(&mut self.store, ())?;
        let weights_ptr = self.fn_get_nurbs_weights.call(&mut self.store, ())?;
        let weights_len = self.fn_get_nurbs_weights_len.call(&mut self.store, ())?;

        Ok(NurbsCurveData {
            degree,
            rational,
            periodic,
            knots: self.read_f64_slice(knots_ptr as u32, knots_len)?,
            multiplicities: self.read_i32_slice(mult_ptr as u32, mult_len)?,
            poles: self.read_f64_slice(poles_ptr as u32, poles_len)?,
            weights: self.read_f64_slice(weights_ptr as u32, weights_len)?,
        })
    }

    /// Read an evolution data result.
    pub(crate) fn read_evolution_result(&mut self) -> OcctResult<EvolutionData> {
        let result_id = self.fn_get_evo_result_id.call(&mut self.store, ())?;
        let mod_ptr = self.fn_get_evo_modified.call(&mut self.store, ())?;
        let mod_len = self.fn_get_evo_modified_len.call(&mut self.store, ())?;
        let gen_ptr = self.fn_get_evo_generated.call(&mut self.store, ())?;
        let gen_len = self.fn_get_evo_generated_len.call(&mut self.store, ())?;
        let del_ptr = self.fn_get_evo_deleted.call(&mut self.store, ())?;
        let del_len = self.fn_get_evo_deleted_len.call(&mut self.store, ())?;

        Ok(EvolutionData {
            result_id,
            modified: self.read_i32_slice(mod_ptr as u32, mod_len)?,
            generated: self.read_i32_slice(gen_ptr as u32, gen_len)?,
            deleted: self.read_i32_slice(del_ptr as u32, del_len)?,
        })
    }

    /// Read a projection data result.
    pub(crate) fn read_projection_result(&mut self) -> OcctResult<ProjectionData> {
        Ok(ProjectionData {
            visible_outline: ShapeHandle(
                self.fn_get_proj_visible_outline.call(&mut self.store, ())?,
            ),
            visible_smooth: ShapeHandle(self.fn_get_proj_visible_smooth.call(&mut self.store, ())?),
            visible_sharp: ShapeHandle(self.fn_get_proj_visible_sharp.call(&mut self.store, ())?),
            hidden_outline: ShapeHandle(self.fn_get_proj_hidden_outline.call(&mut self.store, ())?),
            hidden_smooth: ShapeHandle(self.fn_get_proj_hidden_smooth.call(&mut self.store, ())?),
            hidden_sharp: ShapeHandle(self.fn_get_proj_hidden_sharp.call(&mut self.store, ())?),
        })
    }

    /// Read a label info result.
    pub(crate) fn read_label_info_result(&mut self) -> OcctResult<LabelInfo> {
        let label_id = self.fn_get_label_info_label_id.call(&mut self.store, ())?;
        let name_ptr = self.fn_get_label_info_name.call(&mut self.store, ())?;
        let name_len = self.fn_get_label_info_name_len.call(&mut self.store, ())?;
        let name_bytes = self.read_bytes(name_ptr as u32, name_len)?;
        let name = String::from_utf8(name_bytes).map_err(|e| OcctError::Memory(e.to_string()))?;

        Ok(LabelInfo {
            label_id,
            name,
            has_color: self.fn_get_label_info_has_color.call(&mut self.store, ())? != 0,
            r: self.fn_get_label_info_r.call(&mut self.store, ())?,
            g: self.fn_get_label_info_g.call(&mut self.store, ())?,
            b: self.fn_get_label_info_b.call(&mut self.store, ())?,
            is_assembly: self
                .fn_get_label_info_is_assembly
                .call(&mut self.store, ())?
                != 0,
            is_component: self
                .fn_get_label_info_is_component
                .call(&mut self.store, ())?
                != 0,
            shape_id: self.fn_get_label_info_shape_id.call(&mut self.store, ())?,
        })
    }
}

impl Drop for OcctKernel {
    fn drop(&mut self) {
        // Best-effort cleanup
        if let Ok(destroy) = self
            .instance
            .get_typed_func::<(), ()>(&mut self.store, "occt_destroy")
        {
            let _ = destroy.call(&mut self.store, ());
        }
    }
}

/// Decompress the embedded brotli-compressed WASM binary.
fn decompress_wasm() -> OcctResult<Vec<u8>> {
    let mut output = Vec::new();
    let mut input: &[u8] = WASM_BINARY;
    brotli::BrotliDecompress(&mut input, &mut output)
        .map_err(|e| OcctError::Memory(format!("brotli decompression failed: {e}")))?;
    Ok(output)
}