Add mjmBody and mjmPlugin and their compiler C APIs.

PiperOrigin-RevId: 604937231
Change-Id: Ib8a2105ce6c0500d6a610258b46f192d9e73169d

src/user/user_api.h

@@ -1,4 +1,4 @@
-// Copyright 2021 DeepMind Technologies Limited
+// Copyright 2024 DeepMind Technologies Limited
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -17,14 +17,20 @@
 
 #include <mujoco/mjexport.h>
 #include <mujoco/mjmodel.h>
+#include <mujoco/mjtnum.h>
 
 typedef struct _mjString* mjString;
 typedef struct _mjDouble* mjDouble;
 typedef struct _mjElement* mjElement;
 
 
+// this is a C-API
+#ifdef __cplusplus
+extern "C" {
+#endif
 
 //---------------------------------- Public structs ------------------------------------------------
+
 typedef struct _mjmOrientation {
   double axisangle[4];            // rotation axis and angle
   double xyaxes[6];               // x and y axes
@@ -32,42 +38,104 @@ typedef struct _mjmOrientation {
   double euler[3];                // euler rotations
 } mjmOrientation;
 
-typedef struct _mjmSite {
-  mjElement element;              // only used internally, do not modify
+
+typedef struct _mjmPlugin {
+  bool active;
+  mjString name;
+  mjString instance_name;
+  mjElement instance;
+} mjmPlugin;
+
+
+typedef struct _mjmBody {
+  mjElement element;              // compiler only, do not modify
   mjString name;                  // name
   mjString classname;             // class name
+  double pos[3];                  // frame position
+  double quat[4];                 // frame orientation
+  mjtByte mocap;                  // is this a mocap body
+  mjmOrientation alt;             // frame alternative orientation
+  double gravcomp;                // gravity compensation
+  mjDouble userdata;              // user data
+  double ipos[3];                 // inertial frame position
+  double iquat[4];                // inertial frame orientation
+  double mass;                    // mass
+  double inertia[3];              // diagonal inertia (in i-frame)
+  mjmOrientation ialt;            // inertial frame alternative orientation
+  double fullinertia[6];          // non-axis-aligned inertia matrix
+  mjtByte explicitinertial;       // whether to save the body with an explicit inertial clause
+  mjmPlugin plugin;               // passive force plugin
   mjString info;                  // message appended to errors
+} mjmBody;
+
+
+typedef struct _mjmSite {
+  mjElement element;              // compiler only, do not modify
+  mjString name;                  // name
+  mjString classname;             // class name
   mjtGeom type;                   // geom type for rendering
   int group;                      // group id, used for visualization
-  double size[3];                 // geom size for rendering
   double pos[3];                  // position
   double quat[4];                 // orientation
   mjString material;              // name of material for rendering
-  mjDouble userdata;              // user data
-  float rgba[4];                  // rgba when material is omitted
+  double size[3];                 // geom size for rendering
   double fromto[6];               // alternative for capsule, cylinder, box, ellipsoid
   mjmOrientation alt;             // alternative orientation specification
+  float rgba[4];                  // rgba when material is omitted
+  mjDouble userdata;              // user data
+  mjString info;                  // message appended to errors
 } mjmSite;
 
+
 //---------------------------------- Public API ----------------------------------------------------
-#ifdef __cplusplus
-extern "C" {
-#endif
 
 // Create model.
 MJAPI void* mjm_createModel();
 
 // Delete model.
-MJAPI void mjm_deleteModel(void* model);
+MJAPI void mjm_deleteModel(void* modelspec);
 
-// Add body to body.
-MJAPI void* mjm_addBody(void* body, void* def);
+// Add child body to body, return child spec.
+MJAPI mjmBody* mjm_addBody(mjmBody* body, void* defspec);
 
-// Add site to body.
-MJAPI mjmSite* mjm_addSite(void* body, void* def);
+// Add site to body, return site spec.
+MJAPI mjmSite* mjm_addSite(mjmBody* body, void* defspec);
 
-// Find object of given type.
-MJAPI void* mjm_findObject(void* model, mjtObj type, const char* name);
+// Add joint to body.
+MJAPI void* mjm_addJoint(mjmBody* body, void* defspec);
+
+// Add freejoint to body.
+MJAPI void* mjm_addFreeJoint(mjmBody* body);
+
+// Add geom to body.
+MJAPI void* mjm_addGeom(mjmBody* body, void* defspec);
+
+// Add camera to body.
+MJAPI void* mjm_addCamera(mjmBody* body, void* defspec);
+
+// Add light to body.
+MJAPI void* mjm_addLight(mjmBody* body, void* defspec);
+
+// Add frame to body.
+MJAPI void* mjm_addFrame(mjmBody* body, void* parentframe);
+
+// Add plugin to model.
+MJAPI mjElement mjm_addPlugin(void* model);
+
+// Get model from body.
+MJAPI void* mjm_getModel(mjmBody* body);
+
+// Get default corresponding to an mjElement.
+MJAPI void* mjm_getDefault(mjElement element);
+
+// Finding body with given name in model.
+MJAPI mjmBody* mjm_findBody(void* modelspec, const char* name);
+
+// Finding body with given name in body.
+MJAPI mjmBody* mjm_findChild(mjmBody* body, const char* name);
+
+// Get element id.
+MJAPI int mjm_getId(mjElement element);
 
 // Copy input text to destination string.
 MJAPI void mjm_setString(mjString dest, const char* text);
@@ -75,14 +143,20 @@ MJAPI void mjm_setString(mjString dest, const char* text);
 // Copy input array to destination vector.
 MJAPI void mjm_setDouble(mjDouble dest, const double* array, int size);
 
-// Get const pointer to mjString data.
+// Get string contents.
 MJAPI const char* mjm_getString(mjString source);
 
-// Get const pointer to mjDouble data and its size.
+// Get double array contents and optionally its size.
 MJAPI const double* mjm_getDouble(mjDouble source, int* size);
 
+// Set default.
+MJAPI void mjm_setDefault(mjElement element, void* defspec);
+
 // Set frame.
-MJAPI void mjm_setFrame(void* dest, void* frame);
+MJAPI void mjm_setFrame(mjElement dest, void* frame);
+
+// Compute quat and inertia from body->fullinertia..
+MJAPI const char* mjm_setFullInertia(mjmBody* body, double quat[4], double inertia[3]);
 
 #ifdef __cplusplus
 }