A Ramp force is a force that steadily increases or decreases in magnitude over time. The Ramp force may act in a single direction or may also change directions.
The sum of the force on a heavy wagon being pushed uphill by an increasingly tired person is an example of a Ramp force. The force of gravity pulls downhill on the wagon with a Constant force throughout. The pusher starts out strong, pushing the load quickly uphill. As he becomes increasingly tired, the upward force he exerts on the wagon decreases. When gravity begins to win, the wagon no longer moves uphill, and slowly begins to move downward in response to gravity. The Ramp force in this situation starts out as a positive force, pushing the wagon uphill, and decreases steadily until it is a negative force, pulling the wagon downhill.
Steering wheels, joysticks and a full force feedback mouse can simulate Ramp forces. A tactile feedback mouse cannot.
Direction
The direction tells you where the force comes from; the location of the origin of the force. Direction for a Ramp force can be specified in Cartesian or polar coordinates, in the same way as for a Constant force.
The direction of a Ramp force specifies the direction whenever the magnitude of the Ramp force is greater than zero. When the force magnitude is less than zero, the direction of the force will be the opposite of that specified for the force as a whole.
Duration
Duration specifies the amount of time the effect lasts in milliseconds. It can range from any finite value greater than 0 to infinity, though an infinite-duration Ramp force will never reach its final magnitude.
Gain
Gain is a factor with which you can scale all the magnitudes of the Ramp effect. It ranges from 0 to 10000, where a gain of 10000 is equivalent to multiplying the forces throughout the effect by a factor of 1.
Magnitude
Magnitude specifies the strength of the force. Two magnitudes are specified for Ramp forces: starting and ending magnitudes. The force begins at the starting magnitude, then changes linearly over time to reach the ending magnitude. If the two magnitudes fall either both positive or both negative then the force will either increase or decrease in a single direction. If one is negative and the other positive, then the force will decrease over time, reverse directions at some point and then increase in strength.
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