public void Test()
{
var simSettings = new SimulationSettings();
simSettings.RenderMode = RenderModes.Normal;
var game = new SimulatorGame(simSettings, IntPtr.Zero);
_collision = new TerrainCollision(game, game);
_collision.Initialize();
_collision.TmpBuildScene();
// Find new position and velocity from a constant acceleration over timestep
const float dt = 0.017f;
var a = new Vector3(0, 9.81f, 0);
var startCondition1 = new TimestepStartingCondition(Vector3.Zero, Vector3.Zero, a,
Quaternion.Identity, TimeSpan.Zero);
TimestepStartingCondition startCondition2 = startCondition1;
var joystickOutput = new JoystickOutput(0.1f, 0.1f, 0, 0.5f);
for (int i = 0; i < 100; i++)
{
TimestepResult jitterResult = ByJitter(startCondition1, joystickOutput,
startCondition1.StartTime + TimeSpan.FromSeconds(dt), dt);
TimestepResult physicsResult = ByPhysics(startCondition2, joystickOutput,
startCondition2.StartTime + TimeSpan.FromSeconds(dt), dt);
Vector3 dPos = jitterResult.Position - physicsResult.Position;
Vector3 dVel = jitterResult.Velocity - physicsResult.Velocity;
if (jitterResult.Orientation != physicsResult.Orientation)
{
float dPitchDeg =
MathHelper.ToDegrees(VectorHelper.GetPitchAngle(jitterResult.Orientation) -
VectorHelper.GetPitchAngle(physicsResult.Orientation));
float dRollDeg =
MathHelper.ToDegrees(VectorHelper.GetRollAngle(jitterResult.Orientation) -
VectorHelper.GetRollAngle(physicsResult.Orientation));
float dYawDeg =
MathHelper.ToDegrees(VectorHelper.GetHeadingAngle(jitterResult.Orientation) -
VectorHelper.GetHeadingAngle(physicsResult.Orientation));
Console.WriteLine("YPR delta " + dPitchDeg + " " + dRollDeg + " " + dYawDeg);
}
TimeSpan nextStartTime = physicsResult.EndTime;
startCondition1 = new TimestepStartingCondition(jitterResult.Position, jitterResult.Velocity,
a, jitterResult.Orientation, nextStartTime);
startCondition2 = new TimestepStartingCondition(physicsResult.Position, physicsResult.Velocity,
a, physicsResult.Orientation, nextStartTime);
}
}
/// <summary>Calculates the input and external forces.</summary>
/// <returns>The new orientation and the total acceleration for this orientation in this timestep.</returns>
public SimulationStepResults PerformTimestep(PhysicalHeliState prev, JoystickOutput output, TimeSpan stepDuration,
TimeSpan stepEndTime)
{
if (!_isInitialized)
{
// startCondition.Acceleration = CalculateAcceleration(startCondition.Orientation, startCondition.Velocity, input);
_prevTimestepResult = new TimestepResult(prev.Position, prev.Velocity, prev.Orientation,
stepEndTime - stepDuration);
_isInitialized = true;
}
// If the number of substeps is 0 then only the state at the end of the timestep will be calculated.
// If the number is greater than 1, then the timestep will 1 then a substep will be calculated in the middle of the timestep.
const int substeps = 0;
if (substeps < 0)
{
throw new Exception("The number of substeps is invalid.");
}
TimeSpan substepDuration = stepDuration.Divide(1 + substeps);
Vector3 initialAcceleration = CalculateAcceleration(prev.Orientation, prev.Velocity, output);
var initialState = new TimestepStartingCondition(_prevTimestepResult, initialAcceleration);
//_prevTimestepResult.Result;
// var substepResults = new List<SubstepResults> {initialState};
// We always need to calculate at least the timestep itself, plus any optional substeps.
// Substeps are used to provide sensors with a higher frequency of data than the simulator is capable of rendering real-time.
// const int stepsToCalculate = substeps + 1;
// SubstepResults prevSubstep = initialState;
// for (int i = 0; i < stepsToCalculate; i++)
// {
// prevSubstep.Acceleration = CalculateAcceleration(prevSubstep.Orientation, prevSubstep.Velocity, input);
// SubstepResults r = SimulateStep(prevSubstep, prevSubstep.Acceleration, input, substepDuration, stepEndTime);
//
// substepResults.Add(r);
// prevSubstep = r;
// }
TimestepResult result = SimulateStep(initialState, output, substepDuration, stepEndTime);
//new SimulationStepResults(stepDuration, substepDuration, substepResults);
_prevTimestepResult = result;
// DebugInformation.Time1 = stepEndTime;
// DebugInformation.Q1 = result.Orientation;
//
// DebugInformation.Vectors["Pos"] = result.Position;
// DebugInformation.Vectors["Vel"] = result.Velocity;
// DebugInformation.Vectors["Acc"] = initialAcceleration;
return(new SimulationStepResults(initialState, result, stepEndTime - stepDuration, stepEndTime));
}
private void UpdatePhysicalState(GameTime gameTime, JoystickOutput output, out PhysicalHeliState trueState)
{
_simulationState = _physics.PerformTimestep(_physicalState, output, gameTime.ElapsedGameTime,
gameTime.TotalGameTime);
TimestepResult final = _simulationState.Result;
// We need to use the second last simulation substep to obtain the current acceleration used
// because the entire substep has constant acceleration and it makes no sense
// to use the acceleration calculated for the state after the timestep because no animation will occur after it.
// TODO Support substeps
Vector3 currentAcceleration = _simulationState.StartingCondition.Acceleration;
trueState = new PhysicalHeliState(final.Orientation, final.Position, final.Velocity, currentAcceleration);
}
public void Update(SimulationStepResults step, JoystickOutput output)
{
// TODO Use substeps in physics simulation when sensors require higher frequency than the main-loop runs at
// Currently we simply use the state at the start of the timestep to feed into the sensors, so they read the state
// that was before any motion took place in that timestep.
// Later we may need to update sensors multiple times for each timestep.
TimestepStartingCondition start = step.StartingCondition;
TimestepResult end = step.Result;
var startPhysicalState = new PhysicalHeliState(start.Orientation, start.Position, start.Velocity,
start.Acceleration);
var endPhysicalState = new PhysicalHeliState(end.Orientation, end.Position, end.Velocity,
new Vector3(float.NaN));
// Update all sensors
foreach (ISensor sensor in _sensors)
{
sensor.Update(startPhysicalState, endPhysicalState, output, step.StartTime, step.EndTime);
}
}