refactor: use joints array size to track joint count

AlmasB · AlmasB · commit c52d0ef87138 · 2022-04-16T08:38:48.000+01:00
diff --git a/fxgl-entity/src/main/java/com/almasb/fxgl/physics/box2d/dynamics/World.java b/fxgl-entity/src/main/java/com/almasb/fxgl/physics/box2d/dynamics/World.java
@@ -65,7 +65,6 @@ public final class World {
     private Array<Body> bodies = new Array<>(WORLD_POOL_SIZE);
 
     private Array<Joint> joints = new Array<>();
-    private int jointCount = 0;
 
     private final Vec2 gravity = new Vec2();
 
@@ -128,7 +127,6 @@ public <T extends Joint> T createJoint(JointDef<T> def) {
         T j = Joint.create(this, def);
 
         joints.add(j);
-        ++jointCount;
 
         // Connect to the bodies' doubly linked lists.
         j.m_edgeA.joint = j;
@@ -215,8 +213,6 @@ public void destroyJoint(Joint j) {
 
         Joint.destroy(j);
 
-        --jointCount;
-
         // If the joint prevents collisions, then flag any contacts for filtering.
         if (!collideConnected) {
             flagContactsForFiltering(bodyA, bodyB);
@@ -308,7 +304,7 @@ private void solve(TimeStep step) {
         }
 
         // Size the island for the worst case.
-        island.init(getBodyCount(), contactManager.contactCount, jointCount, contactManager.getContactListener());
+        island.init(getBodyCount(), contactManager.contactCount, getJointCount(), contactManager.getContactListener());
 
         // Clear all the island flags.
         for (Body b : bodies) {
@@ -1189,7 +1185,7 @@ public int getBodyCount() {
      * @return the number of joints
      */
     public int getJointCount() {
-        return jointCount;
+        return joints.size();
     }
 
     /**
diff --git a/fxgl-entity/src/test/kotlin/com/almasb/fxgl/physics/box2d/dynamics/WorldTest.kt b/fxgl-entity/src/test/kotlin/com/almasb/fxgl/physics/box2d/dynamics/WorldTest.kt
@@ -7,6 +7,11 @@
 package com.almasb.fxgl.physics.box2d.dynamics
 
 import com.almasb.fxgl.core.math.Vec2
+import com.almasb.fxgl.physics.box2d.dynamics.joints.RevoluteJointDef
+import org.hamcrest.CoreMatchers
+import org.hamcrest.CoreMatchers.*
+import org.hamcrest.MatcherAssert
+import org.hamcrest.MatcherAssert.*
 import org.junit.jupiter.api.Assertions.*
 import org.junit.jupiter.api.Test
 
@@ -22,4 +27,20 @@ class WorldTest {
 
         assertNotNull(world.contactManager.broadPhase)
     }
+
+    @Test
+    fun `joint count`() {
+        val world = World(Vec2())
+
+        val jointDef = RevoluteJointDef()
+        jointDef.initialize(Body(BodyDef(), world), Body(BodyDef(), world), Vec2())
+
+        val joint = world.createJoint(jointDef)
+
+        assertThat(world.jointCount, `is`(1))
+
+        world.destroyJoint(joint)
+
+        assertThat(world.jointCount, `is`(0))
+    }
 }
