private void UpdateVisualProperties(Particle particle, ParticleValues values)
{
particle.LayerDepth = particle.AgeInFrames / (float)values.AgeInFrames;
particle.Scale = values.Scale[particle.AgeInFrames] + particle.PengInput * _scaleInputScale;
particle.Alpha = values.Alpha[particle.AgeInFrames] + particle.PengInput * _alphaInputScale;
}
public bool Update(Particle particle)
{
// Note: This method is run potentially very often. It must be kept quick.
var precalcIndex = Math.Abs(particle.Random) % PRECALC_COUNT;
var values = _precalculatedValues[precalcIndex];
if (particle.AgeInFrames >= values.AgeInFrames)
{
if (_areParticlesImmortal)
particle.AgeInFrames -= values.AgeInFrames; // Restart iteration through precalculated values.
else
return true;
}
UpdateVisualProperties(particle, values);
UpdatePhysicalProperties(particle, values);
particle.AgeInFrames++;
return false;
}
private void UpdatePhysicalProperties(Particle particle, ParticleValues values)
{
var acceleration = values.Acceleration[particle.AgeInFrames] + particle.PengInput * _accelerationInputScale;
var rotationSpeed = values.RotationSpeed[particle.AgeInFrames] + particle.PengInput * _rotationSpeedInputScale;
particle.Pos += particle.Move * _elapsedSeconds;
particle.Move += particle.DirectionVector * acceleration * _elapsedSeconds;
particle.Rotation += rotationSpeed * _elapsedSeconds;
particle.Move *= _dragMultiplier;
}
private void GobCreation(Gob gob, int createCount, int i, int emitType, ref List<Particle> particles)
{
// Find out emission parameters.
// We have to loop because some choices of parameters may not be wanted.
int maxAttempts = 20;
bool attemptOk = false;
for (int attempt = 0; !attemptOk && attempt < maxAttempts; ++attempt)
{
bool lastAttempt = attempt == maxAttempts - 1;
attemptOk = true;
int random = RandomHelper.GetRandomInt();
float directionAngle, rotation;
Vector2 directionUnit, pos, move;
switch (Peng.ParticleCoordinates)
{
case Peng.CoordinateSystem.Peng:
RandomHelper.GetRandomCirclePoint(_radius, -_sprayAngle, _sprayAngle,
out pos, out directionUnit, out directionAngle);
move = _initialVelocity.GetValue(0, random) * directionUnit;
switch (_facingType)
{
case FacingType.Directed: rotation = 0; break;
case FacingType.Forward: rotation = directionAngle; break;
case FacingType.Random: rotation = RandomHelper.GetRandomFloat(0, MathHelper.TwoPi); break;
default: throw new Exception("SprayEmitter: Unhandled particle facing type " + _facingType);
}
break;
case Peng.CoordinateSystem.Game:
{
float posWeight = (i + 1) / (float)createCount;
var startPos = Peng.OldDrawPos;
var endPos = Peng.Pos + Peng.DrawPosOffset;
var iPos = Vector2.Lerp(startPos, endPos, posWeight);
var drawRotation = Peng.Rotation + Peng.DrawRotationOffset;
RandomHelper.GetRandomCirclePoint(_radius, drawRotation - _sprayAngle, drawRotation + _sprayAngle,
out pos, out directionUnit, out directionAngle);
pos += iPos;
move = Peng.Move + _initialVelocity.GetValue(0, random) * directionUnit;
// HACK: 'move' will be added to 'pos' in PhysicalUpdater during this same frame
pos -= move * (float)Peng.Game.GameTime.ElapsedGameTime.TotalSeconds;
switch (_facingType)
{
case FacingType.Directed: rotation = Peng.Rotation; break;
case FacingType.Forward: rotation = directionAngle; break;
case FacingType.Random: rotation = RandomHelper.GetRandomFloat(0, MathHelper.TwoPi); break;
default: throw new Exception("SprayEmitter: Unhandled particle facing type " + _facingType);
}
}
break;
case Peng.CoordinateSystem.FixedToPeng:
pos = Vector2.Zero;
move = Vector2.Zero;
rotation = 0;
directionAngle = 0;
break;
default:
throw new ApplicationException("SprayEmitter: Unhandled peng coordinate system " + Peng.ParticleCoordinates);
}
// Set the thing's parameters.
if (emitType < TextureNames.Length)
{
var particle = new Particle
{
Alpha = 1,
Move = move,
PengInput = Peng.Input,
Pos = pos,
Random = random,
Direction = directionAngle,
DirectionVector = Vector2.UnitX.Rotate(directionAngle),
Rotation = rotation,
Scale = 1,
Texture = Peng.Game.Content.Load<Texture2D>(TextureNames[emitType]),
};
particles.Add(particle);
}
else
{
// Bail out if the position is not free for the gob.
if (!lastAttempt && !Peng.Arena.IsFreePosition(new Circle(pos, Gob.SMALL_GOB_PHYSICAL_RADIUS)))
{
attemptOk = false;
continue;
}
gob.Owner = Peng.Owner;
gob.ResetPos(pos, move, rotation);
Peng.Arena.Gobs.Add(gob);
}
}
}
