Add benchmark program,

bin/bench2d.dart

@@ -0,0 +1,157 @@
+/*******************************************************************************
+ * Copyright (c) 2015, Daniel Murphy, Google
+ * All rights reserved.
+ * 
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *  * Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ ******************************************************************************/
+
+import '../lib/box2d/box2d.dart';
+
+main() {
+  Bench2D bench = new Bench2D();
+  bench.warmup();
+  bench.bench();
+}
+
+class Bench2D {
+  static const bool DEBUG = false;
+  static const bool CHECKSUM = false;
+
+  static const int FRAMES = 256;
+  static const int PYRAMID_SIZE = 40;
+
+  World world;
+  Body groundBody;
+
+  double meanF(List<double> values) {
+    double total = 0.0;
+    for (int i = 0; i < FRAMES; ++i) {
+      total += values[i];
+    }
+    return total / FRAMES;
+  }
+
+  // Simple nearest-rank %ile (on sorted array). We should have enough samples to make this reasonable.
+  double percentile(List<double> values, double pc) {
+    int rank = (pc * values.length) ~/ 100;
+    return values[rank];
+  }
+
+  List<double> bench() {
+    List<double> times = new List<double>(FRAMES);
+    Stopwatch stopwatch = new Stopwatch()..start();
+    for (int i = 0; i < FRAMES; ++i) {
+      int begin = stopwatch.elapsedMilliseconds;
+      step();
+      int end = stopwatch.elapsedMilliseconds;
+      times[i] = (end - begin).toDouble();
+      log("${times[i]}");
+    }
+
+    times.sort();
+    double mean = meanF(times);
+    double fifth = percentile(times, 5.0);
+    double ninetyFifth = percentile(times, 95.0);
+    print("Benchmark complete.\nms/frame: $mean 5th %ile: ${percentile(times, 5.0)} 95th %ile: ${percentile(times, 95.0)}");
+    if (CHECKSUM) {
+      checksum(world);
+    }
+    return <double>[mean, fifth, ninetyFifth];
+  }
+
+  void warmup() {
+    for (int i = 0; i < FRAMES; ++i) {
+      step();
+    }
+  }
+
+  Body topBody = null;
+
+  Bench2D() {
+    Vec2 gravity = new Vec2(0.0, -10.0);
+    world = new World.withGravity(gravity);
+
+    {
+      BodyDef bd = new BodyDef();
+      Body ground = world.createBody(bd);
+
+      EdgeShape shape = new EdgeShape();
+      shape.set(new Vec2(-40.0, 0.0), new Vec2(40.0, 0.0));
+      ground.createFixtureFromShape(shape, 0.0);
+    }
+
+    {
+      double a = .5;
+      PolygonShape shape = new PolygonShape();
+      shape.setAsBoxXY(a, a);
+
+      Vec2 x = new Vec2(-7.0, 0.75);
+      Vec2 y = new Vec2.zero();
+      Vec2 deltaX = new Vec2(0.5625, 1.0);
+      Vec2 deltaY = new Vec2(1.125, 0.0);
+
+      for (int i = 0; i < PYRAMID_SIZE; ++i) {
+        y.set(x);
+
+        for (int j = i; j < PYRAMID_SIZE; ++j) {
+          BodyDef bd = new BodyDef();
+          bd.type = BodyType.DYNAMIC;
+          bd.position.set(y);
+          Body body = world.createBody(bd);
+          body.createFixtureFromShape(shape, 5.0);
+          topBody = body;
+          y.addLocal(deltaY);
+        }
+
+        x.addLocal(deltaX);
+      }
+    }
+  }
+
+  static int stepCount = 0;
+
+  void step() {
+    double timeStep = 1.0 / 60.0;
+    world.stepDt(timeStep, 3, 3);
+    stepCount++;
+  }
+
+  void checksum(World world) {
+    Vec2 positionSum = new Vec2.zero();
+    Vec2 linearVelocitySum = new Vec2.zero();
+    double angularVelocitySum = 0.0;
+    var checksum = (Body b) {
+      positionSum = positionSum.add(b.getPosition());
+      linearVelocitySum = linearVelocitySum.add(b.getLinearVelocity());
+      angularVelocitySum += b.getAngularVelocity();
+    };
+    Body firstBody = world.m_bodyList;
+    print(firstBody);
+    world.forEachBody(checksum);
+    print("pos: $positionSum linVel $linearVelocitySum angVel $angularVelocitySum");
+  }
+
+  void log(String msg) {
+    if (DEBUG) {
+      print(msg);
+    }
+  }
+}
+