public void AddCircle(MovingCircle c)
{
World.Objects.Add(c);
Canvas.Children.Add(c.circle);
Canvas.SetLeft(c.circle, c.Position.X);
Canvas.SetTop(c.circle, c.Position.Y);
}
public void CalculateSpeedAndPositionFromCollisions(MovingCircle obj, int myIndex, int len)
{
// We only detect collisions for bodies after us in the list
for (int i = myIndex + 1; i < len; ++i)
{
MovingCircle other = Objects[i];
Vector centerToCenter = (other.Center - obj.Center);
double centerToCenterLen = centerToCenter.Length;
// If they collide
if ( centerToCenterLen <= other.Radius + obj.Radius )
{
// We get the translation necessary to move one
Vector a = centerToCenter * (obj.Radius / centerToCenterLen);
Vector b = centerToCenter * (centerToCenterLen - other.Radius) / centerToCenterLen;
Vector middle = (a - b) / 2;
obj.Position -= middle;
other.Position += middle;
// Now we've positioned the cicles, we can normalize the centerToCenter vector in order to convert it into a unit vector
centerToCenter.Normalize();
// http://ericleong.me/research/circle-circle/#static-circle-circle-collision-detection
double p = 2 * (obj.Speed.X * centerToCenter.X + obj.Speed.Y * centerToCenter.Y - other.Speed.X * centerToCenter.X - other.Speed.Y * centerToCenter.Y) / (obj.Mass + other.Mass);
obj.Speed = new Vector(obj.Speed.X - p * other.Mass * centerToCenter.X,
obj.Speed.Y - p * other.Mass * centerToCenter.Y)
* obj.BounceFactor;
other.Speed = new Vector(other.Speed.X + p * obj.Mass * centerToCenter.X,
other.Speed.Y + p * obj.Mass * centerToCenter.Y)
* other.BounceFactor;
/* Original: Seems to have switched both masses, since a high-mass sphere bounces like heck
obj.Speed = new Vector(obj.Speed.X - p * obj.Mass * centerToCenter.X,
obj.Speed.Y - p * obj.Mass * centerToCenter.Y)
* obj.BounceFactor;
other.Speed = new Vector(other.Speed.X + p * other.Mass * centerToCenter.X,
other.Speed.Y + p * other.Mass * centerToCenter.Y)
* other.BounceFactor;
*/
}
}
if (obj.Position.Y < 0) {
obj.Speed = new Vector(obj.Speed.X, Math.Abs(obj.Speed.Y) * obj.BounceFactor);
obj.Position = new Point(obj.Position.X, 0);
} else if (obj.Position.Y + obj.Diameter > this.Height) {
obj.Speed = new Vector(obj.Speed.X, -Math.Abs(obj.Speed.Y) * obj.BounceFactor);
obj.Position = new Point(obj.Position.X, this.Height - obj.Diameter);
}
if (obj.Position.X < 0) {
obj.Position = new Point(0, obj.Position.Y);
obj.Speed = new Vector(-obj.Speed.X * obj.BounceFactor, obj.Speed.Y);
} else if (obj.Position.X + obj.Diameter > this.Width) {
obj.Position = new Point(this.Width - obj.Diameter, obj.Position.Y);
obj.Speed = new Vector(-obj.Speed.X * obj.BounceFactor, obj.Speed.Y);
}
}
public Vector force(MovingCircle obj, int myIndex, int len)
{
Vector f = PrecalculatedDeltaFCache[myIndex];
// Vector f = new Vector(0.0, 9.8) * obj.Mass
// Actually the gravity is in px/s/s... Lol
f += new Vector(0.0, this.Gravity) * obj.Mass; // Gravity
// We only detect collisions for bodies after us in the list
for (int i = myIndex + 1; i < len; ++i)
{
MovingCircle other = Objects[i];
Vector centerToCenter = (other.Center - obj.Center);
// If they collide
// NOTE: Instead of length < o1.radius + o2.radius we use LengthSquared, since it's faster
// (Obtaining the length needs a square root)
if ( centerToCenter.LengthSquared < other.Radius * other.Radius + obj.Radius * obj.Radius )
{
// Now we've positioned the cicles, we can normalize the centerToCenter vector in order to convert it into a unit vector
centerToCenter.Normalize();
// Add the linear momentum and substract the normal
f += other.Speed * other.Mass;
f -= obj.Speed * obj.Mass;
PrecalculatedDeltaFCache[i] += obj.Speed * obj.Mass;
PrecalculatedDeltaFCache[i] -= other.Speed * other.Mass;
}
}
// if ( object touches boundary )
// f += normal; (f = 0);
// TODO: Consider using < instead of <=
if (obj.Position.Y < 0) {
if (Gravity < 0)
f += new Vector(0, obj.Mass * -this.Gravity);
f += new Vector(0, -obj.Speed.Y * obj.Mass);
} else if (obj.Position.Y + obj.Diameter > this.Height) {
if (Gravity > 0)
f += new Vector(0, obj.Mass * -this.Gravity);
f += new Vector(0, -obj.Speed.Y * obj.Mass);
}
if (obj.Position.X < 0) {
// Lineal moment:
// p = m * v
// F = dp/dt
f += new Vector(obj.Mass * -obj.Speed.X, 0);
} else if (obj.Position.X + obj.Diameter > this.Width) {
// Lineal moment:
// p = m * v
// F = dp/dt
f += new Vector(obj.Mass * -obj.Speed.X, 0);
}
return f;
}
