Fall 2009ACS-1805 Ron McFadyen1 Point of View An object’s Point of View comprises its position and orientation. Position tells us where the object is in the world. Orientation tells us the direction an object is facing. An object’s position is given by 3 values: location in the world’s LR axis, location in the world’s FB axis, location in the world’s UD axis. See the pointOfView.position property values. An object’s orientation is given by 3 values: yaw, pitch, roll. Yaw is the objects rotation about the UD axis. Pitch is the object’s rotation about the LR axis. Roll is the object’s rotation about the FB axis. See The PointOfView property for objects

Fall 2009ACS-1805 Ron McFadyen2 Orientation of objects Each object has its own coordinate system that provides its own sense of direction If Bob is asked to turn left ¼ revolution, Bob’s sense of direction turns with him forward Bob Note here that Bob rotated on his up-down axis. An object’s yaw is how much the object is rotated along this up-down axis since its original position.

Fall 2009ACS-1805 Ron McFadyen3 Orientation of objects Bob had just turned… Now if we ask Bob to move forward, Bob advances along the forward-backward axis forward

Fall 2009ACS-1805 Ron McFadyen4 Orientation of objects Bob had moved forward… Now if we ask Bob to turn forward, Bob rotates on the left- right axis forward right Note here that Bob rotated on his left-right axis. An object’s pitch is how much the object is rotated along this left-right axis since its original position.

Fall 2009ACS-1805 Ron McFadyen5 Orientation of objects Consider Bob back at … Now if we ask Bob to roll left, Bob rotates on the forward- backward axis Note here that Bob rotated on his forward- backward axis. An object’s roll is how much the object is rotated along this forward-backward axis since its original position. forward

Fall 2009ACS-1805 Ron McFadyen6 Orientation of objects Each object has its own coordinate system that provides its own sense of direction If Dave and Peter are asked to move forward, they go in opposite directions You reset an object’s coordinate system by using orient to to give both the same sense of direction Dave orient to Peter forward Dave Peter

Fall 2009ACS-1805 Ron McFadyen7 Orientation of objects You reset an object’s coordinate system and location by using set point of view Dave set point of view Peter forward Dave Peter

Fall 2009ACS-1805 Ron McFadyen8 Move, Turn, Roll Action ParametersSample object Moveleft, right, forward, back, up, downany object Turnleft, right, forward, backdoor Rollleft, rightknob, dial forward Dave

Fall 2009ACS-1805 Ron McFadyen9 Move, Turn, Roll MoveTurnRoll e.g.liddialknob door

Fall 2009ACS-1805 Ron McFadyen10 Arguments Duration: the default length of time for an action is one second – this can be modified Style: the smoothness of an action is controlled using one of the values begin gently, begin abruptly, end gently, end abruptly As seen by: the sense of direction (orientation) for an action is by default determined by the object that is acting, but this can be changed by specifying a different object to use for direction