1 files changed, 136 insertions, 0 deletions
diff --git a/tests/box2d/Benchmark.cpp b/tests/box2d/Benchmark.cpp
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+++ b/tests/box2d/Benchmark.cpp
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+
+
+//
+// Based on joelgwebber's Box2D benchmarks,
+// https://github.com/joelgwebber/bench2d/blob/master/c/Bench2d.cpp
+//
+
+
+// Settings =====================
+// Turn this on to include the y-position of the top box in the output.
+#define DEBUG 0
+
+int WARMUP;
+int FRAMES;
+
+typedef struct {
+  float mean;
+  float stddev;
+} result_t;
+// ==============================
+
+
+
+#include <cstdio>
+#include <time.h>
+#include <math.h>
+
+#include "Box2D/Box2D.h"
+
+using namespace std;
+
+const int e_count = 40;
+
+result_t measure(clock_t *times) {
+  float values[FRAMES];
+  result_t r;
+
+	float total = 0;
+	for (int i = 0; i < FRAMES; ++i) {
+		values[i] = (float)times[i] / CLOCKS_PER_SEC * 1000;
+		total += values[i];
+	}
+  r.mean = total / FRAMES;
+
+  float variance = 0;
+	for (int i = 0; i < FRAMES; ++i) {
+		float diff = values[i] - r.mean;
+		variance += diff * diff;
+	}
+  r.stddev = sqrt(variance / FRAMES);
+
+  return r;
+}
+
+int main(int argc, char **argv) {
+  int arg = argc > 1 ? argv[1][0] - '0' : 3;
+  switch(arg) {
+    case 0: return 0; break;
+    case 1: WARMUP = 5; FRAMES = 35; break;
+    case 2: WARMUP = 32; FRAMES = 161; break;
+    case 3: WARMUP = 64; FRAMES = 333; break;
+    case 4: WARMUP = 5*64; FRAMES = 7*333; break;
+    case 5: WARMUP = 10*64; FRAMES = 17*333; break;
+    default: printf("error: %d\\n", arg); return -1;
+  }
+
+	// Define the gravity vector.
+	b2Vec2 gravity(0.0f, -10.0f);
+
+	// Construct a world object, which will hold and simulate the rigid bodies.
+	b2World world(gravity);
+  world.SetAllowSleeping(false);
+
+	{
+		b2BodyDef bd;
+		b2Body* ground = world.CreateBody(&bd);
+
+		b2EdgeShape shape;
+		shape.Set(b2Vec2(-40.0f, 0.0f), b2Vec2(40.0f, 0.0f));
+		ground->CreateFixture(&shape, 0.0f);
+	}
+
+  b2Body* topBody;
+
+	{
+		float32 a = 0.5f;
+		b2PolygonShape shape;
+		shape.SetAsBox(a, a);
+
+		b2Vec2 x(-7.0f, 0.75f);
+		b2Vec2 y;
+		b2Vec2 deltaX(0.5625f, 1);
+		b2Vec2 deltaY(1.125f, 0.0f);
+
+		for (int32 i = 0; i < e_count; ++i) {
+			y = x;
+
+			for (int32 j = i; j < e_count; ++j) {
+				b2BodyDef bd;
+				bd.type = b2_dynamicBody;
+				bd.position = y;
+				b2Body* body = world.CreateBody(&bd);
+				body->CreateFixture(&shape, 5.0f);
+
+        topBody = body;
+
+				y += deltaY;
+			}
+
+			x += deltaX;
+		}
+	}
+
+	for (int32 i = 0; i < WARMUP; ++i) {
+		world.Step(1.0f/60.0f, 3, 3);
+  }
+
+	clock_t times[FRAMES]; 
+	for (int32 i = 0; i < FRAMES; ++i) {
+		clock_t start = clock();
+		world.Step(1.0f/60.0f, 3, 3);
+		clock_t end = clock();
+		times[i] = end - start;
+#if DEBUG
+    printf("%f :: ", topBody->GetPosition().y);
+		printf("%f\n", (float32)(end - start) / CLOCKS_PER_SEC * 1000);
+#endif
+	}
+
+  result_t result = measure(times);
+
+  printf("frame averages: %.3f +- %.3f\n", result.mean, result.stddev);
+
+  return 0;
+}
+