public void step(int pause)
        {
            ds.SetColor(1.0f, 1.0f, 0.0f);
            ds.SetTexture(ds.Texture.Wood);
            lock (_prims)
            {
                foreach (OdePrim prm in _prims)
                {
                    //IntPtr body = d.GeomGetBody(prm.prim_geom);
                    if (prm.prim_geom != IntPtr.Zero)
                    {
                        d.Vector3 pos;
                        d.GeomCopyPosition(prm.prim_geom, out pos);
                        //d.BodyCopyPosition(body, out pos);

                        d.Matrix3 R;
                        d.GeomCopyRotation(prm.prim_geom, out R);
                        //d.BodyCopyRotation(body, out R);

                        d.Vector3 sides = new d.Vector3();
                        sides.X = prm.Size.X;
                        sides.Y = prm.Size.Y;
                        sides.Z = prm.Size.Z;

                        ds.DrawBox(ref pos, ref R, ref sides);
                    }
                }
            }
            ds.SetColor(1.0f, 0.0f, 0.0f);
            lock (_characters)
            {
                foreach (OdeCharacter chr in _characters)
                {
                    if (chr.Shell != IntPtr.Zero)
                    {
                        IntPtr body = d.GeomGetBody(chr.Shell);

                        d.Vector3 pos;
                        d.GeomCopyPosition(chr.Shell, out pos);
                        //d.BodyCopyPosition(body, out pos);

                        d.Matrix3 R;
                        d.GeomCopyRotation(chr.Shell, out R);
                        //d.BodyCopyRotation(body, out R);

                        ds.DrawCapsule(ref pos, ref R, chr.Size.Z, 0.35f);
                        d.Vector3 sides = new d.Vector3();
                        sides.X = 0.5f;
                        sides.Y = 0.5f;
                        sides.Z = 0.5f;

                        ds.DrawBox(ref pos, ref R, ref sides);
                    }
                }
            }
        }
        // Keyboard callback
        public void command(int cmd)
        {
            IntPtr geom;
            d.Mass mass;
            d.Vector3 sides = new d.Vector3(d.RandReal() * 0.5f + 0.1f, d.RandReal() * 0.5f + 0.1f, d.RandReal() * 0.5f + 0.1f);

            Char ch = Char.ToLower((Char)cmd);
            switch ((Char)ch)
            {
                case 'w':
                    try
                    {
                        Vector3 rotate = (new Vector3(1, 0, 0) * Quaternion.CreateFromEulers(hpr.Z * Utils.DEG_TO_RAD, hpr.Y * Utils.DEG_TO_RAD, hpr.X * Utils.DEG_TO_RAD));

                        xyz.X += rotate.X; xyz.Y += rotate.Y; xyz.Z += rotate.Z;
                        ds.SetViewpoint(ref xyz, ref hpr);
                    }
                    catch (ArgumentException)
                    { hpr.X = 0; }
                    break;

                case 'a':
                    hpr.X++;
                    ds.SetViewpoint(ref xyz, ref hpr);
                    break;

                case 's':
                    try
                    {
                        Vector3 rotate2 = (new Vector3(-1, 0, 0) * Quaternion.CreateFromEulers(hpr.Z * Utils.DEG_TO_RAD, hpr.Y * Utils.DEG_TO_RAD, hpr.X * Utils.DEG_TO_RAD));

                        xyz.X += rotate2.X; xyz.Y += rotate2.Y; xyz.Z += rotate2.Z;
                        ds.SetViewpoint(ref xyz, ref hpr);
                    }
                    catch (ArgumentException)
                    { hpr.X = 0; }
                    break;
                case 'd':
                    hpr.X--;
                    ds.SetViewpoint(ref xyz, ref hpr);
                    break;
                case 'r':
                    xyz.Z++;
                    ds.SetViewpoint(ref xyz, ref hpr);
                    break;
                case 'f':
                    xyz.Z--;
                    ds.SetViewpoint(ref xyz, ref hpr);
                    break;
                case 'e':
                    xyz.Y++;
                    ds.SetViewpoint(ref xyz, ref hpr);
                    break;
                case 'q':
                    xyz.Y--;
                    ds.SetViewpoint(ref xyz, ref hpr);
                    break;
            }
        }