add single step simulation, using 'o' key. use 'i' key to suspend simulation first

default background color a bit darker, to show debug lines
tweaked contact point rendering a bit

examples/ExampleBrowser/OpenGLExampleBrowser.cpp

@@ -123,6 +123,7 @@ static bool enable_experimental_opencl = false;
 
 int gDebugDrawFlags = 0;
 static bool pauseSimulation=false;
+static bool singleStepSimulation = false;
 int midiBaseIndex = 176;
 extern bool gDisableDeactivation;
 
@@ -227,6 +228,12 @@ void MyKeyboardCallback(int key, int state)
 	{
 		pauseSimulation = !pauseSimulation;
 	}
+	if (key == 'o' && state)
+	{
+		singleStepSimulation = true;
+	}
+
+
 #ifndef NO_OPENGL3
 	if (key=='s' && state)
 	{
@@ -1124,12 +1131,12 @@ void OpenGLExampleBrowser::update(float deltaTime)
 		
 		if (sCurrentDemo)
 		{
-			if (!pauseSimulation)
+			if (!pauseSimulation || singleStepSimulation)
 			{
+				singleStepSimulation = false;
 				//printf("---------------------------------------------------\n");
 				//printf("Framecount = %d\n",frameCount);
-
-
+				
 				if (gFixedTimeStep>0)
 				{
 					sCurrentDemo->stepSimulation(gFixedTimeStep);