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Add support for UsdPhysicsMaterialAPI and create MjcMaterialAPI for missing attributes.

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PiperOrigin-RevId: 782942169
Change-Id: I344b5e47d1d63c9d4e50173cb6a96d0af177ec9e
This commit is contained in:
Sam Haves
2025-07-14 09:52:00 -07:00
committed by Copybara-Service
parent 7d5b360dea
commit 92bcbeb5d3
11 changed files with 594 additions and 15 deletions
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src/experimental/usd/plugins/mjcf/mujoco_to_usd.cc
+57
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@@ -84,6 +84,7 @@ TF_DEFINE_PRIVATE_TOKENS(kTokens,
((light, "Light"))
((meshScope, "MeshSources"))
((materialsScope, "Materials"))
((physicsMaterialsScope, "PhysicsMaterials"))
((previewSurface, "PreviewSurface"))
((keyframesScope, "Keyframes"))
((actuatorsScope, "Actuators"))
@@ -744,6 +745,48 @@ class ModelWriter {
return texture_output_attrs;
}
pxr::SdfPath WritePhysicsMaterial(mjsGeom *geom) {
pxr::SdfPath scope_path =
body_paths_[kWorldIndex].AppendChild(kTokens->physicsMaterialsScope);
if (!data_->HasSpec(scope_path)) {
CreatePrimSpec(data_, body_paths_[kWorldIndex],
kTokens->physicsMaterialsScope, pxr::UsdGeomTokens->Scope);
}
auto name = GetAvailablePrimName(*mjs_getName(geom->element),
pxr::UsdShadeTokens->Material, scope_path);
pxr::SdfPath material_path =
CreatePrimSpec(data_, scope_path, name, pxr::UsdShadeTokens->Material);
ApplyApiSchema(data_, material_path,
pxr::UsdPhysicsTokens->PhysicsMaterialAPI);
ApplyApiSchema(data_, material_path,
MjcPhysicsTokens->MjcMaterialAPI);
mjsGeom *geom_default = mjs_getDefault(geom->element)->geom;
if (geom->friction[0] != geom_default->friction[0]) {
WriteUniformAttribute(material_path, pxr::SdfValueTypeNames->Float,
pxr::UsdPhysicsTokens->physicsStaticFriction,
(float)geom->friction[0]);
WriteUniformAttribute(material_path, pxr::SdfValueTypeNames->Float,
pxr::UsdPhysicsTokens->physicsDynamicFriction,
(float)geom->friction[0]);
}
if (geom->friction[1] != geom_default->friction[1]) {
WriteUniformAttribute(material_path, pxr::SdfValueTypeNames->Double,
MjcPhysicsTokens->mjcTorsionalfriction,
geom->friction[1]);
}
if (geom->friction[2] != geom_default->friction[2]) {
WriteUniformAttribute(material_path, pxr::SdfValueTypeNames->Double,
MjcPhysicsTokens->mjcRollingfriction,
geom->friction[2]);
}
return material_path;
}
void WriteMaterial(mjsMaterial *material, const pxr::SdfPath &parent_path) {
// Create a Material prim.
auto name =
@@ -1551,6 +1594,20 @@ class ModelWriter {
SetAttributeDefault(data_, density_attr, (float)geom->density);
}
mjsDefault *geom_default = mjs_getDefault(geom->element);
if (geom->friction[0] != geom_default->geom->friction[0] ||
geom->friction[1] != geom_default->geom->friction[1] ||
geom->friction[2] != geom_default->geom->friction[2]) {
pxr::SdfPath physics_material_path = WritePhysicsMaterial(geom);
ApplyApiSchema(data_, geom_path,
pxr::UsdShadeTokens->MaterialBindingAPI);
// Bind the material to this geom.
CreateRelationshipSpec(
data_, geom_path, pxr::UsdShadeTokens->materialBinding,
physics_material_path, pxr::SdfVariabilityUniform);
}
// For meshes, also apply PhysicsMeshCollisionAPI and set the
// approximation attribute.
if (geom->type == mjGEOM_MESH) {