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Add aliases for MjModel loading functions and expose string constants as properties.

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Introduces `from_xml_path` and `from_binary_path` as more idiomatic aliases for `mj_loadXML` and `mj_loadModel` respectively. Refactors the binding of `mj*STRING` constants. Instead of exposing `get_mj*STRING` functions, these constants are now available as properties on the `Module` object. Runtime getters are added via EM_ASM to lazily call the underlying C++ functions.

PiperOrigin-RevId: 882566011
Change-Id: Id3bd5c23704fd122af30a50aed089bd3143fbc96
This commit is contained in:
Google DeepMind
2026-03-12 06:58:20 -07:00
committed by Copybara-Service
parent a62501f305
commit df0bc58578
5 changed files with 85 additions and 14 deletions
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wasm/README.md
+13 -5
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@@ -348,23 +348,31 @@ mujoco.mjtDisableBit.mjDSBL_CLAMPCTRL.value
```
### Constants
Scalar constants will be accessed the same way they are on python, simply:
Scalar constants can be accessed as properties:
```javascript
mujoco.mjNEQDATA
```
Due to Embind limitations, more complex constants that are not scalar, but are
represented in more dimensions are exposed as functions. E.g. to use
`mujoco.mjFRAMESTRING` you will need to call a function:
Non-scalar constants like `mjFRAMESTRING` are also accessed as properties, and
return JavaScript arrays:
```javascript
mujoco.get_mjFRAMESTRING()
mujoco.mjFRAMESTRING
```
This will return a javascript array representation of the values in MuJoCo
`mjFRAMESTRING`.
> [!NOTE]
> You will notice constants like `mjFRAMESTRING` are typed as `any`. This is
> because they are bound using `emscripten::val::array()` in C++, and Embind
> maps `emscripten::val` to `any` in TypeScript definition files. While
> `EMSCRIPTEN_DECLARE_VAL_TYPE(StringArray)` could be used to define
> `StringArray` as an alias for `emscripten::val` and hint to Embind how to
> handle conversions in function signatures or when using `.as()` it does not
> change how `emscripten::constant` infers types for properties.
## Development
In order to change the bindings you will need to change the [`bindings.cc`](codegen/generated/bindings.cc)
wasm/codegen/generated/bindings.cc
+29 -1
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@@ -11597,8 +11597,11 @@ EMSCRIPTEN_BINDINGS(mujoco_bindings) {
.property("uselimit", &MjLROpt::uselimit, &MjLROpt::set_uselimit, reference());
emscripten::class_<MjModel>("MjModel")
.class_function("mj_loadXML", emscripten::select_overload<std::unique_ptr<MjModel>(std::string)>(&mj_loadXML_wrapper_1))
.class_function("from_xml_path", emscripten::select_overload<std::unique_ptr<MjModel>(std::string)>(&mj_loadXML_wrapper_1))
.class_function("mj_loadXML", emscripten::select_overload<std::unique_ptr<MjModel>(std::string, const MjVFS&)>(&mj_loadXML_wrapper_2))
.class_function("from_xml_path", emscripten::select_overload<std::unique_ptr<MjModel>(std::string, const MjVFS&)>(&mj_loadXML_wrapper_2))
.class_function("mj_loadModel", &mj_loadModel_wrapper)
.class_function("from_binary_path", &mj_loadModel_wrapper)
.constructor<const MjModel &>()
// Binds the functions on MjModel that return accessors.
#define X_ACCESSOR(NAME, Name, OBJTYPE, field_name, nfield) \
@@ -13409,6 +13412,7 @@ EMSCRIPTEN_BINDINGS(mujoco_bindings) {
.function("GetView", &WasmBuffer<uint8_t>::GetView);
emscripten::register_vector<std::string>("mjStringVec");
emscripten::register_vector<std::vector<std::string>>("mjStringVecVec");
emscripten::register_vector<int>("mjIntVec");
emscripten::register_vector<mjIntVec>("mjIntVecVec");
emscripten::register_vector<float>("mjFloatVec");
@@ -13453,7 +13457,6 @@ EMSCRIPTEN_BINDINGS(mujoco_bindings) {
emscripten::constant("mjPI", mjPI);
emscripten::constant("mjVERSION_HEADER", mjVERSION_HEADER);
// These complex constants are bound using function() rather than constant()
emscripten::function("get_mjDISABLESTRING", &get_mjDISABLESTRING);
emscripten::function("get_mjENABLESTRING", &get_mjENABLESTRING);
emscripten::function("get_mjFRAMESTRING", &get_mjFRAMESTRING);
@@ -13461,6 +13464,31 @@ EMSCRIPTEN_BINDINGS(mujoco_bindings) {
emscripten::function("get_mjRNDSTRING", &get_mjRNDSTRING);
emscripten::function("get_mjTIMERSTRING", &get_mjTIMERSTRING);
emscripten::function("get_mjVISSTRING", &get_mjVISSTRING);
// Bind these complex constants as properties on the module object.
// We use emscripten::constant with emscripten::val::array() to type them
// as `any` in TypeScript. At runtime, the EM_ASM block below overrides
// these properties with getters that return native JavaScript arrays
// (string[] or string[][]) via the get_ functions above, which is more
// performant and idiomatic than vector wrappers.
emscripten::constant("mjDISABLESTRING", emscripten::val::array());
emscripten::constant("mjENABLESTRING", emscripten::val::array());
emscripten::constant("mjFRAMESTRING", emscripten::val::array());
emscripten::constant("mjLABELSTRING", emscripten::val::array());
emscripten::constant("mjRNDSTRING", emscripten::val::array());
emscripten::constant("mjTIMERSTRING", emscripten::val::array());
emscripten::constant("mjVISSTRING", emscripten::val::array());
EM_ASM({
if (typeof Module !== "undefined") {
"mjDISABLESTRING mjENABLESTRING mjFRAMESTRING mjLABELSTRING mjRNDSTRING mjTIMERSTRING mjVISSTRING".split(" ").forEach(function(name) {
Object.defineProperty(Module, name, {
get: function() { return Module["get_" + name](); },
set: function(v) { },
enumerable: true,
configurable: true
});
});
}
});
}
} // namespace mujoco::wasm
wasm/codegen/generators/structs.py
+10
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@@ -553,15 +553,25 @@ def _build_struct_bindings(
'.class_function("mj_loadXML",'
" emscripten::select_overload<std::unique_ptr<MjModel>(std::string)>(&mj_loadXML_wrapper_1))"
)
builder.line(
'.class_function("from_xml_path",'
" emscripten::select_overload<std::unique_ptr<MjModel>(std::string)>(&mj_loadXML_wrapper_1))"
)
builder.line(
'.class_function("mj_loadXML",'
" emscripten::select_overload<std::unique_ptr<MjModel>(std::string,"
" const MjVFS&)>(&mj_loadXML_wrapper_2))"
)
builder.line(
'.class_function("from_xml_path",'
" emscripten::select_overload<std::unique_ptr<MjModel>(std::string,"
" const MjVFS&)>(&mj_loadXML_wrapper_2))"
)
f2 = common.wrapped_function_name(
introspect_functions.FUNCTIONS["mj_loadModel"]
)
builder.line(f'.class_function("mj_loadModel", &{f2})')
builder.line(f'.class_function("from_binary_path", &{f2})')
builder.line(".constructor<const MjModel &>()")
builder.line("""
// Binds the functions on MjModel that return accessors.
wasm/codegen/templates/bindings.cc
+26 -1
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@@ -875,6 +875,7 @@ EMSCRIPTEN_BINDINGS(mujoco_bindings) {
.function("GetView", &WasmBuffer<uint8_t>::GetView);
emscripten::register_vector<std::string>("mjStringVec");
emscripten::register_vector<std::vector<std::string>>("mjStringVecVec");
emscripten::register_vector<int>("mjIntVec");
emscripten::register_vector<mjIntVec>("mjIntVecVec");
emscripten::register_vector<float>("mjFloatVec");
@@ -919,7 +920,6 @@ EMSCRIPTEN_BINDINGS(mujoco_bindings) {
emscripten::constant("mjPI", mjPI);
emscripten::constant("mjVERSION_HEADER", mjVERSION_HEADER);
// These complex constants are bound using function() rather than constant()
emscripten::function("get_mjDISABLESTRING", &get_mjDISABLESTRING);
emscripten::function("get_mjENABLESTRING", &get_mjENABLESTRING);
emscripten::function("get_mjFRAMESTRING", &get_mjFRAMESTRING);
@@ -927,6 +927,31 @@ EMSCRIPTEN_BINDINGS(mujoco_bindings) {
emscripten::function("get_mjRNDSTRING", &get_mjRNDSTRING);
emscripten::function("get_mjTIMERSTRING", &get_mjTIMERSTRING);
emscripten::function("get_mjVISSTRING", &get_mjVISSTRING);
// Bind these complex constants as properties on the module object.
// We use emscripten::constant with emscripten::val::array() to type them
// as `any` in TypeScript. At runtime, the EM_ASM block below overrides
// these properties with getters that return native JavaScript arrays
// (string[] or string[][]) via the get_ functions above, which is more
// performant and idiomatic than vector wrappers.
emscripten::constant("mjDISABLESTRING", emscripten::val::array());
emscripten::constant("mjENABLESTRING", emscripten::val::array());
emscripten::constant("mjFRAMESTRING", emscripten::val::array());
emscripten::constant("mjLABELSTRING", emscripten::val::array());
emscripten::constant("mjRNDSTRING", emscripten::val::array());
emscripten::constant("mjTIMERSTRING", emscripten::val::array());
emscripten::constant("mjVISSTRING", emscripten::val::array());
EM_ASM({
if (typeof Module !== "undefined") {
"mjDISABLESTRING mjENABLESTRING mjFRAMESTRING mjLABELSTRING mjRNDSTRING mjTIMERSTRING mjVISSTRING".split(" ").forEach(function(name) {
Object.defineProperty(Module, name, {
get: function() { return Module["get_" + name](); },
set: function(v) { },
enumerable: true,
configurable: true
});
});
}
});
}
} // namespace mujoco::wasm
wasm/tests/bindings_test.ts
+7 -7
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@@ -683,24 +683,24 @@ describe('MuJoCo WASM Bindings', () => {
it('should check constants values', () => {
expect(mujoco.mjNEQDATA).toBe(11);
expect(mujoco.get_mjDISABLESTRING()).toEqual([
expect(mujoco.mjDISABLESTRING).toEqual([
'Constraint', 'Equality', 'Frictionloss', 'Limit', 'Contact', 'Spring',
'Damper', 'Gravity', 'Clampctrl', 'Warmstart', 'Filterparent',
'Actuation', 'Refsafe', 'Sensor', 'Midphase', 'Eulerdamp', 'AutoReset',
'NativeCCD', 'Island'
]);
expect(mujoco.get_mjRNDSTRING()).toEqual([
expect(mujoco.mjRNDSTRING).toEqual([
['Shadow', '1', 'S'], ['Wireframe', '0', 'W'], ['Reflection', '1', 'R'],
['Additive', '0', 'L'], ['Skybox', '1', 'K'], ['Fog', '0', 'G'],
['Haze', '1', '/'], ['Depth', '0', ''], ['Segment', '0', ','],
['Id Color', '0', ''], ['Cull Face', '1', '']
]);
expect(mujoco.get_mjFRAMESTRING().length)
.toEqual(mujoco.mjtFrame.mjNFRAME.value);
expect(mujoco.get_mjVISSTRING().length)
expect(mujoco.mjFRAMESTRING.length).toEqual(mujoco.mjtFrame.mjNFRAME.value);
expect(mujoco.mjVISSTRING.length)
.toEqual(mujoco.mjtVisFlag.mjNVISFLAG.value);
expect(mujoco.get_mjVISSTRING()[mujoco.mjtVisFlag.mjVIS_INERTIA.value])
.toEqual(['Inertia', '0', 'I']);
expect(mujoco.mjVISSTRING[mujoco.mjtVisFlag.mjVIS_INERTIA.value]).toEqual([
'Inertia', '0', 'I'
]);
});
it('should create a spec from XML', () => {