private void BallCollision(ScreenObject ball1, ScreenObject ball2)
{
#region vars
float accuracy = Global.currentGame.TEST_accuracy;
float tpivot1;
float tpivot2;
double difference;
float d; //distance between
double phi1; //angle of collision
Vector2 Fg12 = Vector2.Zero; //gravitational force by particle 1 on particle 2
Vector2 Fg21 = Vector2.Zero;
double dmin; //r1 + r2
float masses;
float axis; //flag telling collision axis points NESW or NWSE
//ball 1
Vector2 displacement1 = Vector2.Zero;
Vector2 v12; //velocity on collision axis
Vector2 a12; //acceleration on collision axis
double v12mag;
Vector2 v11; //velocity not on collision axis
double v12fmag; //result of 1d collision along axis of collision
Vector2 v12f;
Vector2 v1f;
double vAlignment1; //alignment of collision to velocity
double cvtheta1; //angle between collision and velocity
double vtheta1; //angle of velocity
//ball 2
Vector2 displacement2 = Vector2.Zero;
Vector2 v22; //velocity on collision axis
Vector2 a22; //acceleration on collision axis
double v22mag;
Vector2 v21; //velocity not on collision axis
double v22fmag; //result of 1d collision along axis of collision
Vector2 v22f;
Vector2 v2f;
double vAlignment2; //alignment of collision to velocity
double cvtheta2;
double phi2; //angle of collision
double vtheta2; //angle of velocity
double atheta1;
double catheta1;
double aAlignment1;
double a12mag;
double a22mag;
double atheta2;
double catheta2;
double aAlignment2;
#endregion
//if bullet doesnt hit cue, return
//if (ball1 is Bullet && ball2 is BilliardBall)
// if (((BilliardBall)ball2).type != BilliardBall.TYPE_CUE) return;
//else if (ball2 is Bullet && ball1 is BilliardBall)
// if (((BilliardBall)ball1).type != BilliardBall.TYPE_CUE) return;
d = Vector2.Distance(ball2.location, ball1.location);
dmin = ball1.sRadius + ball2.sRadius;
difference = dmin - d;
if (difference > accuracy)
{
masses = ball1.mass + ball2.mass;
if (d < dmin)
{
ball1.hit = true;
ball2.hit = true;
}
#region displacement correction
//Because the field is updated discretely, collisions will always overshoot and need corrections
//correction of location
//note that with an acceleration, velocity should be corrected as well
//acceleration will be corrected with gravity section
//will need recursion here to check for extra collisions after corrections
tpivot1 = ball1.t;
tpivot2 = ball2.t;
//the justification of this while loop is demonstrated in test 1 and 2
while (!(difference > -accuracy && difference < accuracy) && tpivot1 > accuracy && tpivot2 > accuracy)
{ //quicksort to t when objs first contact
tpivot1 /= 2;
tpivot2 /= 2;
if (difference > accuracy)
{
ball1.t -= tpivot1;
ball2.t -= tpivot2;
}
else
{
ball1.t += tpivot1;
ball2.t += tpivot2;
}
//replace this with modified update from BilliardBall.TEST_BounceOnScreenWalls
ball1.ModifiedUpdate();
ball2.ModifiedUpdate();
d = Vector2.Distance(ball2.location, ball1.location);
difference = dmin - d;
}
phi1 = Math.Atan2((ball2.location.Y - ball1.location.Y), (ball2.location.X - ball1.location.X));
#endregion
if (Math.Abs(difference) < accuracy)
{
#region circular collision detection
axis = (float)Math.Tan(phi1);
axis /= Math.Abs(axis);
if (float.IsNaN(axis))
{
axis = -1;
}
//ball 1
vtheta1 = Math.Atan2(ball1.velocity.Y, ball1.velocity.X);
cvtheta1 = phi1 - vtheta1;
vAlignment1 = Math.Cos(cvtheta1);
v12 = new Vector2((float)((ball1.velocity.Length() * vAlignment1) * Math.Cos(phi1)), (float)((ball1.velocity.Length() * vAlignment1) * Math.Sin(phi1)));
v11 = ball1.velocity - v12; //split velocity into 2 vectors
if (v12.X < 0)
{
v12mag = v12.Length() * -1; //flatten along x axis
}
else
{
v12mag = v12.Length();
}
//ball 2
phi2 = phi1 + Math.PI;
vtheta2 = Math.Atan2(ball2.velocity.Y, ball2.velocity.X);
cvtheta2 = phi2 - vtheta2;
vAlignment2 = Math.Cos(cvtheta2);
v22 = new Vector2((float)((ball2.velocity.Length() * vAlignment2) * Math.Cos(phi2)), (float)((ball2.velocity.Length() * vAlignment2) * Math.Sin(phi2)));
v21 = ball2.velocity - v22; //split velocity into 2 vectors
if (v22.X < 0)
{
v22mag = v22.Length() * -1; //flatten along x axis
}
else
{
v22mag = v22.Length();
}
//conservation of momentum
if (ball1.mass == ball2.mass || masses == 0)
{
v12fmag = v22mag;
v22fmag = v12mag;
}
else
{
v12fmag = ((ball1.mass - ball2.mass) / masses) * v12mag + ((2 * ball2.mass) / masses) * v22mag; //1d collision
v22fmag = ((ball1.mass * 2) / masses) * v12mag + ((ball2.mass - ball1.mass) / masses) * v22mag;
}
v12f = new Vector2((float)(v12fmag * Math.Abs(Math.Cos(phi1))), (float)(v12fmag * axis * Math.Abs(Math.Sin(phi1)))); //unflatten
v22f = new Vector2((float)(v22fmag * Math.Abs(Math.Cos(phi2))), (float)(v22fmag * axis * Math.Abs(Math.Sin(phi2))));
v1f = v12f + v11;
v2f = v22f + v21;
ball1.velocity = v1f;
ball2.velocity = v2f;
#endregion
}
//need to use old code if balls bounce into another in one frame
//can be removed after recursion is implemented
else
{
#region old displacement correction
//Because the field is updated discretely, collisions will always overshoot and need corrections
//correction of location
//note that with an acceleration, velocity should be corrected as well
//acceleration will be corrected with gravity section
difference = dmin;
difference -= d;
Vector2 dx = new Vector2((float)(difference * Math.Cos(phi1)), (float)(difference * Math.Sin(phi1)));
if (masses == 0)
{
displacement2 = dx / 2;
displacement1 = -displacement2;
ball2.location += displacement2;
ball1.location += displacement1;
ball2.updateAbsLoc();
ball1.updateAbsLoc();
}
else
{
displacement2 = dx * (ball1.mass / masses);
displacement1 = -dx * (ball2.mass / masses);
ball2.location += displacement2;
ball1.location += displacement1;
ball2.updateAbsLoc();
ball1.updateAbsLoc();
}
d = Vector2.Distance(ball2.location, ball1.location);
#endregion
#region old circular collision detection
axis = (float)Math.Tan(phi1);
axis /= Math.Abs(axis);
if (float.IsNaN(axis))
{
axis = -1;
}
//ball 1
vtheta1 = Math.Atan2(ball1.velocity.Y, ball1.velocity.X);
cvtheta1 = phi1 - vtheta1;
vAlignment1 = Math.Cos(cvtheta1);
v12 = new Vector2((float)((ball1.velocity.Length() * vAlignment1) * Math.Cos(phi1)), (float)((ball1.velocity.Length() * vAlignment1) * Math.Sin(phi1)));
v11 = ball1.velocity - v12; //split velocity into 2 vectors
if (v12.X < 0)
{
v12mag = v12.Length() * -1; //flatten along x axis
}
else
{
v12mag = v12.Length();
}
//velocity correction
if (ball1.oldAcceleration.Length() > 0)
{
atheta1 = Math.Atan2(ball1.oldAcceleration.Y, ball1.oldAcceleration.X);
catheta1 = phi1 - atheta1;
aAlignment1 = Math.Cos(catheta1);
a12 = new Vector2((float)((ball1.oldAcceleration.Length() * aAlignment1) * Math.Cos(phi1)), (float)((ball1.oldAcceleration.Length() * aAlignment1) * Math.Sin(phi1)));
if (a12.X < 0)
{
a12mag = a12.Length() * -1;
}
else
{
a12mag = a12.Length();
}
if (v12mag < 0)
{
if (displacement1.X < 0)
{
v12mag = -(Math.Sqrt((v12mag * v12mag) - 2 * a12mag * displacement1.Length())); //Vxf^2 = Vxi^2 + 2 * a * (xf - xi)
}
else
{
v12mag = -(Math.Sqrt((v12mag * v12mag) + 2 * a12mag * displacement1.Length()));
}
}
else
{
if (displacement1.X < 0)
{
v12mag = Math.Sqrt((v12mag * v12mag) - 2 * a12mag * displacement1.Length()); //Vxf^2 = Vxi^2 + 2 * a * (xf - xi)
}
else
{
v12mag = Math.Sqrt((v12mag * v12mag) + 2 * a12mag * displacement1.Length());
}
}
if (double.IsNaN(v12mag))
{
v12mag = 0;
}
}
//ball 2
phi2 = phi1 + Math.PI;
vtheta2 = Math.Atan2(ball2.velocity.Y, ball2.velocity.X);
cvtheta2 = phi2 - vtheta2;
vAlignment2 = Math.Cos(cvtheta2);
v22 = new Vector2((float)((ball2.velocity.Length() * vAlignment2) * Math.Cos(phi2)), (float)((ball2.velocity.Length() * vAlignment2) * Math.Sin(phi2)));
v21 = ball2.velocity - v22; //split velocity into 2 vectors
if (v22.X < 0)
{
v22mag = v22.Length() * -1; //flatten along x axis
}
else
{
v22mag = v22.Length();
}
//velocity correction
if (ball2.oldAcceleration.Length() > 0)
{
atheta2 = Math.Atan2(ball2.oldAcceleration.Y, ball2.oldAcceleration.X);
catheta2 = phi2 - atheta2;
aAlignment2 = Math.Cos(catheta2);
a22 = new Vector2((float)((ball2.oldAcceleration.Length() * aAlignment2) * Math.Cos(phi2)), (float)((ball2.oldAcceleration.Length() * aAlignment2) * Math.Sin(phi2)));
if (a22.X < 0)
{
a22mag = a22.Length() * -1;
}
else
{
a22mag = a22.Length();
}
if (v22mag < 0)
{
if (displacement2.X < 0)
{
v22mag = -(Math.Sqrt((v22mag * v22mag) - 2 * a22mag * displacement2.Length())); //Vxf^2 = Vxi^2 + 2 * a * (xf - xi)
}
else
{
v22mag = -(Math.Sqrt((v22mag * v22mag) + 2 * a22mag * displacement2.Length()));
}
}
else
{
if (displacement2.X < 0)
{
v22mag = Math.Sqrt((v22mag * v22mag) - 2 * a22mag * displacement2.Length()); //Vxf^2 = Vxi^2 + 2 * a * (xf - xi)
}
else
{
v22mag = Math.Sqrt((v22mag * v22mag) + 2 * a22mag * displacement2.Length());
}
}
if (double.IsNaN(v22mag))
{
v22mag = 0;
}
}
//conservation of momentum
if (ball1.mass == ball2.mass || masses == 0)
{
v12fmag = v22mag;
v22fmag = v12mag;
}
else
{
v12fmag = ((ball1.mass - ball2.mass) / masses) * v12mag + ((2 * ball2.mass) / masses) * v22mag; //1d collision
v22fmag = ((ball1.mass * 2) / masses) * v12mag + ((ball2.mass - ball1.mass) / masses) * v22mag;
}
v12f = new Vector2((float)(v12fmag * Math.Abs(Math.Cos(phi1))), (float)(v12fmag * axis * Math.Abs(Math.Sin(phi1)))); //unflatten
v22f = new Vector2((float)(v22fmag * Math.Abs(Math.Cos(phi2))), (float)(v22fmag * axis * Math.Abs(Math.Sin(phi2))));
v1f = v12f + v11;
v2f = v22f + v21;
ball1.velocity = v1f;
ball2.velocity = v2f;
#endregion
}
#region friction between particles
#endregion
ball1.oldLocation = ball1.location;
ball1.oldVelocity = ball1.velocity;
ball2.oldLocation = ball2.location;
ball2.oldVelocity = ball2.velocity;
}
else
{
phi1 = Math.Atan2((ball2.location.Y - ball1.location.Y), (ball2.location.X - ball1.location.X));
}
//Gravity(ball1, ball2, d, phi1);
}
