--- a/src/PhysicsObject.cc	Mon Dec 08 11:10:04 2008 +0000
+++ b/src/PhysicsObject.cc	Mon Dec 08 12:02:20 2008 +0000
@@ -7,8 +7,18 @@
 
 PhysicsObject::PhysicsObject (PhysicsWorld &world, float mass, Vector position, Vector velocity, ObjectType type, 
             float collision_elasticity, bool enabled) :
-    world(world), position(position), velocity(velocity), mass(mass), inAir(true), aim(0), facing(FACING_RIGHT), 
-    alive(false), shouldDelete(false), type(type), pivot(NULL), collision_elasticity(collision_elasticity)
+    world(world), 
+    position(position), 
+    velocity(velocity), 
+    mass(mass), 
+    inAir(true), 
+    collision_elasticity(collision_elasticity),
+    aim(0), 
+    facing(FACING_RIGHT), 
+    alive(false),
+    shouldDelete(false), 
+    type(type), 
+    pivot(NULL)
 {  
     if (enabled)
         enable();  
@@ -152,7 +162,7 @@
         // If, however, there's a force caused by a bomb, e.g., set it in air.
         // Still, we have to be able to separate forces caused by walking attempts
         // and bombs etc (+0.1 because float comparison can be dangerous)
-        if (total.y < 0.01 || abs(total.x) > PLAYER_MOVE_FORCE + 0.1)
+        if (total.y < 0.01 || fabs(total.x) > PLAYER_MOVE_FORCE + 0.1)
             this->inAir = true;
     }
 
@@ -270,8 +280,8 @@
     velAfterTick = velocity;
     Derivative tmpd;
     Derivative k1 = evaluate(force, 0, tmpd, posAfterTick, velAfterTick);
-    Derivative k2 = evaluate(force, 0.5f*dt, k1, posAfterTick, velAfterTick);
-    Derivative k3 = evaluate(force, 0.5f*dt, k2, posAfterTick, velAfterTick);
+    Derivative k2 = evaluate(force, dt / 2, k1, posAfterTick, velAfterTick);
+    Derivative k3 = evaluate(force, dt / 2, k2, posAfterTick, velAfterTick);
     Derivative k4 = evaluate(force, dt, k3, posAfterTick, velAfterTick);
     
 
@@ -404,6 +414,8 @@
 }
 
 float PhysicsObject::getPivotForce (PhysicsObject *bob) { 
+    (void) bob;
+
     return 0.0; 
 }
 
@@ -426,6 +438,11 @@
     }
     return true;
 }
+    
+void  PhysicsObject::onCollision (Vector collisionPoint, PhysicsObject *other) {
+    (void) collisionPoint;
+    (void) other;
+}
 
 int8_t crossProduct (const Vector &p1, const Vector &p2, const Vector &p3) {
     float p = (p2.x - p1.x)*(p3.y - p1.y) - (p2.y - p1.y)*(p3.x - p1.x);