public void DragIsZeroAtZeroVelocity()
{
var forceCalculator = new VehicleForces(constants.Object);
var vel = Vector2.Zero;
var force = forceCalculator.GetDragForce(vel);
Assert.True(force.Length() < float.Epsilon);
}
public void DragIsProportionalToSpeed(Vector2 vel0, Vector2 vel1)
{
var forceCalculator = new VehicleForces(constants.Object);
var force0 = forceCalculator.GetDragForce(vel0);
var force1 = forceCalculator.GetDragForce(vel1);
Assert.True(force0.Length() < force1.Length());
}
public void GetTractiveForceThrowsWhenGearIndexIsLessThanZero()
{
var forceCalculator = new VehicleForces(constants.Object);
var wheelDirection = new Vector2(0, 1);
var gasPedal = 1.0f;
var gearIdx = -1;
Assert.Throws <ArgumentException>(
() => forceCalculator.GetTractiveForce(gasPedal, wheelDirection, gearIdx)
);
}
public void GetTractiveForceThrowsWhenGearIndexIsOutOfBounds()
{
var forceCalculator = new VehicleForces(constants.Object);
var wheelDirection = new Vector2(0, 1);
var gasPedal = 1.0f;
var gearIdx = constants.Object.NumberOfGears;
Assert.Throws <ArgumentException>(
() => forceCalculator.GetTractiveForce(gasPedal, wheelDirection, gearIdx)
);
}
public void BrakingForceIsProportionalToVelocity(Vector2 velocity0, Vector2 velocity1)
{
var forceCalculator = new VehicleForces(constants.Object);
var brakePedal = 1.0f;
var force0 = forceCalculator.GetBrakingForce(brakePedal, velocity0);
var force1 = forceCalculator.GetBrakingForce(brakePedal, velocity1);
var ratio = force1.Length() / force0.Length();
Assert.True(ratio >= 1);
}
public void TractiveForceIsProportionalToCurrentGear(int gearIdx0, int gearIdx1)
{
var forceCalculator = new VehicleForces(constants.Object);
var wheelDirection = new Vector2(0, 1);
var gasPedal = 1.0f;
var force0 = forceCalculator.GetTractiveForce(gasPedal, wheelDirection, gearIdx0);
var force1 = forceCalculator.GetTractiveForce(gasPedal, wheelDirection, gearIdx1);
var ratio = force1.Length() / force0.Length();
Assert.True(ratio >= 1);
}
public void DragPointsInTheOppositeDirectionOfTheVelocityVector()
{
var forceCalculator = new VehicleForces(constants.Object);
var vel = new Vector2(0, 28);
var force = forceCalculator.GetDragForce(vel);
// NOTE(danielm): dot product of two units vectors is -1 if the
// angle between them is 180deg.
var dot = Vector2.Dot(Vector2.Normalize(force), Vector2.Normalize(vel));
var diff = Math.Abs(-1 - dot);
Assert.True(diff < float.Epsilon);
}
public void TractiveForcePointsInTheReverseDirectionInReverseGear()
{
var forceCalculator = new VehicleForces(constants.Object);
var wheelDirection = new Vector2(0, 1);
var gasPedal = 1.0f;
var force = forceCalculator.GetTractiveForceInReverse(gasPedal, wheelDirection);
// NOTE(danielm): dot product of two units vectors is -1 if the
// angle between them is 180deg.
var dot = Vector2.Dot(Vector2.Normalize(force), Vector2.Normalize(wheelDirection));
var diff = Math.Abs(-1 - dot);
Assert.True(diff < float.Epsilon);
}
public void TractiveForcePointsInTheDirectionOfTheWheels()
{
var forceCalculator = new VehicleForces(constants.Object);
var gear = 1;
var wheelDirection = new Vector2(0, 1);
var gasPedal = 1.0f;
var force = forceCalculator.GetTractiveForce(gasPedal, wheelDirection, gear);
// NOTE(danielm): dot product of two unit vectors is 1 if the
// angle between them is 0 degrees.
var dot = Vector2.Dot(Vector2.Normalize(force), wheelDirection);
var diff = Math.Abs(1 - dot);
Assert.True(diff < float.Epsilon);
}
public void BrakingForceIsProportionalToBrakePedal(float brakePedal0, float brakePedal1)
{
var forceCalculator = new VehicleForces(constants.Object);
var velocity = new Vector2(0, 28);
var force0 = forceCalculator.GetBrakingForce(brakePedal0, velocity);
var force1 = forceCalculator.GetBrakingForce(brakePedal1, velocity);
var ratio = force1.Length() / force0.Length();
var ratioIsGreaterThanOne = ratio > 1;
var ratioEqualsOne = Math.Abs(1 - ratio) < float.Epsilon;
var brakePedalRatiosAreEqual = Math.Abs(brakePedal1 - brakePedal0) < float.Epsilon;
// The ratio is either greater than one OR the ratio is one if and
// only if the brake pedal ratios are equal.
Assert.True(ratioIsGreaterThanOne || ((ratioEqualsOne && brakePedalRatiosAreEqual) || (!ratioEqualsOne && !brakePedalRatiosAreEqual)));
}
