[KT] Box2D idiomatic - To add coverage for property delegation, make …

…a few properties `by lazy`

These also seem to be initialized conditionally. I did a quick test and found that in many (most) cases, the class is instantiated but the property is never initialized, so they seem like good candidates for `by lazy`.

PiperOrigin-RevId: 728827871

samples/box2d/src/main/kotlin/idiomatic/commonMain/org/jbox2d/collision/Collision.kt

@@ -856,8 +856,8 @@ class Collision(private val pool: IWorldPool) {
 
   /** This holds polygon B expressed in frame A. */
   internal class TempPolygon {
-    val vertices = Array<Vec2>(Settings.MAX_POLYGON_VERTICES) { Vec2() }
-    val normals = Array<Vec2>(Settings.MAX_POLYGON_VERTICES) { Vec2() }
+    val vertices: Array<Vec2> by lazy { Array<Vec2>(Settings.MAX_POLYGON_VERTICES) { Vec2() } }
+    val normals: Array<Vec2> by lazy { Array<Vec2>(Settings.MAX_POLYGON_VERTICES) { Vec2() } }
     var count = 0
   }
 

samples/box2d/src/main/kotlin/idiomatic/commonMain/org/jbox2d/collision/Distance.kt

@@ -198,11 +198,7 @@ class Distance {
       }
     }
 
-    /**
-     * this returns pooled objects. don't keep or modify them
-     *
-     * @return
-     */
+    /** this returns pooled objects. don't keep or modify them */
     fun getClosestPoint(out: Vec2) {
       when (count) {
         0 -> {
@@ -448,7 +444,7 @@ class Distance {
    * @author daniel
    */
   class DistanceProxy {
-    val vertices: Array<Vec2> = Array<Vec2>(Settings.MAX_POLYGON_VERTICES) { Vec2() }
+    val vertices: Array<Vec2> by lazy { Array<Vec2>(Settings.MAX_POLYGON_VERTICES) { Vec2() } }
 
     var count: Int = 0
     var radius: Float = 0f
@@ -498,12 +494,7 @@ class Distance {
       }
     }
 
-    /**
-     * Get the supporting vertex index in the given direction.
-     *
-     * @param d
-     * @return
-     */
+    /** Get the supporting vertex index in the given direction. */
     fun getSupport(d: Vec2): Int {
       var bestIndex = 0
       var bestValue = vertices[0] dot d
@@ -517,12 +508,7 @@ class Distance {
       return bestIndex
     }
 
-    /**
-     * Get the supporting vertex in the given direction.
-     *
-     * @param d
-     * @return
-     */
+    /** Get the supporting vertex in the given direction. */
     fun getSupportVertex(d: Vec2): Vec2 {
       var bestIndex = 0
       var bestValue = vertices[0] dot d
@@ -541,10 +527,6 @@ class Distance {
    * Compute the closest points between two shapes. Supports any combination of: CircleShape and
    * PolygonShape. The simplex cache is input/output. On the first call set SimplexCache.count to
    * zero.
-   *
-   * @param output
-   * @param cache
-   * @param input
    */
   fun distance(output: DistanceOutput, cache: SimplexCache, input: DistanceInput) {
     GJK_CALLS++

samples/box2d/src/main/kotlin/idiomatic/commonMain/org/jbox2d/collision/WorldManifold.kt

@@ -39,7 +39,7 @@ class WorldManifold {
   val normal: Vec2 = Vec2()
 
   /** World contact point (point of intersection) */
-  val points: Array<Vec2> = Array<Vec2>(Settings.MAX_MANIFOLD_POINTS) { Vec2() }
+  val points: Array<Vec2> by lazy { Array<Vec2>(Settings.MAX_MANIFOLD_POINTS) { Vec2() } }
   private val pool3 = Vec2()
   private val pool4 = Vec2()
 
@@ -48,7 +48,7 @@ class WorldManifold {
     xfA: Transform,
     radiusA: Float,
     xfB: Transform,
-    radiusB: Float
+    radiusB: Float,
   ) {
     if (manifold.pointCount == 0) {
       return