Limiting Velocity

gistfile1.txt

MAXIMUM_VELOCITY = <any number>;
SQUARED_MAXIMUM_VELOCITY = MAXIMUM_VELOCITY * MAXIMUM_VELOCITY;

function animate(){
    var squared_horizontal_velocity = (x_velocity * x_velocity) + (z_velocity * z_velocity);

    if( squared_horizontal_velocity > SQUARED_MAXIMUM_VELOCITY ){

        var velocity_magnitude = sqrt(squared_horizontal_velocity);
        var scalar = MAXIMUM_VELOCITY / velocity_magnitude;

        x_velocity = x_velocity * scalar;
        z_velocity = z_velocity * scalar;
    }
}