PhysicsSpace: add method to set solver iterations

Thanks to Seppes (see thread: http://hub.jmonkeyengine.org/t/how-to-access-native-bullets-constraintsolver-numiterations)

jme3-bullet-native/src/native/cpp/com_jme3_bullet_PhysicsSpace.cpp

@@ -529,6 +529,18 @@ extern "C" {
         return;
     }
     
+    JNIEXPORT void JNICALL Java_com_jme3_bullet_PhysicsSpace_setSolverNumIterations
+    (JNIEnv *env, jobject object, jlong spaceId, jint value) {
+        jmePhysicsSpace* space = reinterpret_cast<jmePhysicsSpace*>(spaceId);
+        if (space == NULL) {
+            jclass newExc = env->FindClass("java/lang/NullPointerException");
+            env->ThrowNew(newExc, "The physics space does not exist.");
+            return;
+        }
+        
+        space->getDynamicsWorld()->getSolverInfo().m_numIterations = value;
+    }
+
 #ifdef __cplusplus
 }
 #endif

jme3-bullet-native/src/native/cpp/com_jme3_bullet_PhysicsSpace.h

@@ -174,6 +174,14 @@ JNIEXPORT void JNICALL Java_com_jme3_bullet_PhysicsSpace_finalizeNative
 JNIEXPORT void JNICALL Java_com_jme3_bullet_PhysicsSpace_sweepTest_1native
 (JNIEnv *, jobject, jlong, jobject, jobject, jlong, jobject, jfloat);
 
+/*
+ * Class:     com_jme3_bullet_PhysicsSpace
+ * Method:    setSolverNumIterations
+ * Signature: (JI)V
+ */
+JNIEXPORT void JNICALL Java_com_jme3_bullet_PhysicsSpace_setSolverNumIterations
+(JNIEnv *, jobject, jlong, jint);
+
 #ifdef __cplusplus
 }
 #endif

jme3-bullet/src/main/java/com/jme3/bullet/PhysicsSpace.java

@@ -102,6 +102,7 @@ public class PhysicsSpace {
     private Vector3f worldMax = new Vector3f(10000f, 10000f, 10000f);
     private float accuracy = 1f / 60f;
     private int maxSubSteps = 4, rayTestFlags = 1 << 2;
+    private int solverNumIterations = 10;
 
     static {
 //        System.loadLibrary("bulletjme");
@@ -958,6 +959,29 @@ public class PhysicsSpace {
         this.worldMax.set(worldMax);
     }
 
+    /**
+     * Set the number of iterations used by the contact solver.
+     * 
+     * The default is 10. Use 4 for low quality, 20 for high quality.
+     * 
+     * @param numIterations The number of iterations used by the contact & constraint solver.
+     */
+    public void setSolverNumIterations(int numIterations) {
+        this.solverNumIterations = numIterations;
+        setSolverNumIterations(physicsSpaceId, numIterations);
+    }
+    
+    /**
+     * Get the number of iterations used by the contact solver.
+     * 
+     * @return The number of iterations used by the contact & constraint solver.
+     */
+    public int getSolverNumIterations() {
+        return solverNumIterations;
+    }
+    
+    private static native void setSolverNumIterations(long physicsSpaceId, int numIterations);
+    
     public static native void initNativePhysics();
 
     /**

jme3-jbullet/src/main/java/com/jme3/bullet/PhysicsSpace.java

@@ -876,6 +876,21 @@ public class PhysicsSpace {
         this.worldMax.set(worldMax);
     }
     
+    /**
+     * Set the number of iterations used by the contact solver.
+     * 
+     * The default is 10. Use 4 for low quality, 20 for high quality.
+     * 
+     * @param numIterations The number of iterations used by the contact & constraint solver.
+     */
+    public void setSolverNumIterations(int numIterations) {
+        dynamicsWorld.getSolverInfo().numIterations = numIterations;
+    }
+
+    public int getSolverNumIterations() {
+        return dynamicsWorld.getSolverInfo().numIterations;
+    }
+    
     /**
      * interface with Broadphase types
      */