BodyManager: add the 2 public methods

src/main/java/com/github/stephengold/joltjni/BodyManager.java

@@ -23,13 +23,21 @@ of this software and associated documentation files (the "Software"), to deal
 
 import com.github.stephengold.joltjni.readonly.ConstBodyCreationSettings;
 import com.github.stephengold.joltjni.readonly.ConstBodyId;
+import com.github.stephengold.joltjni.readonly.ConstBroadPhaseLayerInterface;
 
 /**
  * A container for bodies.
  *
  * @author Stephen Gold [email protected]
  */
 public class BodyManager extends NonCopyable {
+    // *************************************************************************
+    // fields
+
+    /**
+     * protect the BroadPhaseLayerInterface from garbage collection
+     */
+    private ConstBroadPhaseLayerInterface layerMap;
     // *************************************************************************
     // constructors
 
@@ -173,6 +181,16 @@ public BodyVector getBodies() {
         return result;
     }
 
+    /**
+     * Access the (application-provided) interface for mapping object layers to
+     * broadphase layers.
+     *
+     * @return the pre-existing instance, or {@code null} if none
+     */
+    public ConstBroadPhaseLayerInterface getBroadPhaseLayerInterface() {
+        return layerMap;
+    }
+
     /**
      * Return the maximum number of bodies the manager can support.
      *
@@ -184,6 +202,24 @@ public int getMaxBodies() {
 
         return result;
     }
+
+    /**
+     * Initialize the manager.
+     *
+     * @param maxBodies the desired maximum number of rigid bodies that can be
+     * added
+     * @param numBodyMutexes the desired number of mutexes to allocate, or 0 for
+     * the default number
+     * @param map the desired map from object layers to broad-phase layers (not
+     * null, alias created)
+     */
+    public void init(int maxBodies, int numBodyMutexes,
+            ConstBroadPhaseLayerInterface map) {
+        this.layerMap = map;
+        long managerVa = va();
+        long mapVa = map.va();
+        init(managerVa, maxBodies, numBodyMutexes, mapVa);
+    }
     // *************************************************************************
     // native private methods
 
@@ -205,4 +241,7 @@ native private static void draw(long managerVa, long drawSettingsVa,
     native private static long getBodies(long managerVa);
 
     native private static int getMaxBodies(long managerVa);
+
+    native private static void init(
+            long managerVa, int maxBodies, int numBodyMutexes, long mapVa);
 }

src/main/native/glue/b/BodyManager.cpp

@@ -185,4 +185,17 @@ JNIEXPORT jint JNICALL Java_com_github_stephengold_joltjni_BodyManager_getMaxBod
             = reinterpret_cast<BodyManager *> (managerVa);
     const uint result = pManager->GetMaxBodies();
     return result;
+}
+
+/*
+ * Class:     com_github_stephengold_joltjni_BodyManager
+ * Method:    init
+ * Signature: (JIIJ)V
+ */
+JNIEXPORT void JNICALL Java_com_github_stephengold_joltjni_BodyManager_init
+  (JNIEnv *, jclass, jlong managerVa, jint maxBodies, jint numBodyMutexes, jlong mapVa) {
+    BodyManager * const pManager = reinterpret_cast<BodyManager *> (managerVa);
+    const BroadPhaseLayerInterface * const pMap
+            = reinterpret_cast<BroadPhaseLayerInterface *> (mapVa);
+    pManager->Init(maxBodies, numBodyMutexes, *pMap);
 }