Fall 2009 ACS-1805 Ron McFadyen 1

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

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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

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.

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Orientation of objects

• Bob had just turned…

• Now if we ask Bob to move forward, Bob advances along the forward-backward axis

forward

forward

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Orientation of objects

• Bob had moved forward…

• Now if we ask Bob to turn forward, Bob rotates on the left-right axis

forward

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.

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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

forward

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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

forwardforward

forwardforward

Dave Peter

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Orientation of objects

• You reset an object’s coordinate system and location by using set point of view

• Dave set point of view Peter

forwardforward

forward

Dave Peter

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Move, Turn, Roll

Action Parameters Sample object

Move left, right, forward, back, up, down any object

Turn left, right, forward, back door

Roll left, right knob, dial

forward Dave

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Move, Turn, Roll

Move Turn Roll

e.g. lid dial knob

door

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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