public MightBeCollision Enact(GridManager gridManager, EventManager eventManager, double endtime)
{
if (myPhysicsObject.X != start_x ||
myPhysicsObject.Y != start_y ||
myPhysicsObject.Vx != start_vx ||
myPhysicsObject.Vy != start_vy)
{
return(new MightBeCollision());
}
myPhysicsObject.RemoveFromGrid(gridManager);
myPhysicsObject.X = myPhysicsObject.X + (Time - myPhysicsObject.Time) * myPhysicsObject.Vx;
myPhysicsObject.Y = myPhysicsObject.Y + (Time - myPhysicsObject.Time) * myPhysicsObject.Vy;
myPhysicsObject.Time = Time;
var dx = otherPhysicsObject.X - myPhysicsObject.X;
var dy = otherPhysicsObject.Y - myPhysicsObject.Y;
var normal = new Vector(dx, dy).NewUnitized();
callback(myPhysicsObject);
EventManager.WhatHappensNext(myPhysicsObject, gridManager, eventManager, endtime);
return(new MightBeCollision(new Collision(
myPhysicsObject.X + normal.NewScaled((myPhysicsObject as PhysicsObject <Ball>).shape.Radius).x,
myPhysicsObject.Y + normal.NewScaled((myPhysicsObject as PhysicsObject <Ball>).shape.Radius).y,
normal.x,
normal.y,
true
)));
}
public MightBeCollision Enact(GridManager gridManager, EventManager eventManager, double endTime)
{
if (physicsObject1.X != start_x1 ||
physicsObject1.Y != start_y1 ||
physicsObject2.X != start_x2 ||
physicsObject2.Y != start_y2 ||
physicsObject1.Vx != start_vx1 ||
physicsObject1.Vy != start_vy1 ||
physicsObject2.Vx != start_vx2 ||
physicsObject2.Vy != start_vy2)
{
return(new MightBeCollision());
}
physicsObject1.RemoveFromGrid(gridManager);
physicsObject2.RemoveFromGrid(gridManager);
physicsObject1.X = x1;
physicsObject1.Y = y1;
physicsObject1.Time = Time;
physicsObject2.X = x2;
physicsObject2.Y = y2;
physicsObject2.Time = Time;
// update the V of both
// when a collision happen how does it go down?
// the velocities we care about are normal to the line
// we find the normal and take the dot product
var dx = physicsObject1.X - physicsObject2.X;
var dy = physicsObject1.Y - physicsObject2.Y;
var normal = new Vector(dx, dy).NewUnitized();
var v1 = normal.Dot(physicsObject1.Velocity);
var m1 = physicsObject1.Mass;
var v2 = normal.Dot(physicsObject2.Velocity);
var m2 = physicsObject2.Mass;
MightBeCollision res;
if (physicsObject1.Mobile == false)
{
physicsObject2.Velocity = normal.NewScaled(-2 * v2).NewAdded(physicsObject2.Velocity);
res = new MightBeCollision(new Collision(
physicsObject2.X + normal.NewScaled((physicsObject2 as PhysicsObject <Ball>).shape.Radius).x,
physicsObject2.Y + normal.NewScaled((physicsObject2 as PhysicsObject <Ball>).shape.Radius).y,
normal.NewScaled(-2 * v2 * m2).x,
normal.NewScaled(-2 * v2 * m2).y,
false
));
}
else if (physicsObject2.Mobile == false)
{
physicsObject1.Velocity = normal.NewScaled(-2 * v1).NewAdded(physicsObject1.Velocity);
res = new MightBeCollision(new Collision(
physicsObject2.X + normal.NewScaled((physicsObject2 as PhysicsObject <Ball>).shape.Radius).x,
physicsObject2.Y + normal.NewScaled((physicsObject2 as PhysicsObject <Ball>).shape.Radius).y,
normal.NewScaled(-2 * v1 * m1).x,
normal.NewScaled(-2 * v1 * m1).y,
false
));
}
else
{
// we do the physics and we get a quadratic for vf2
var c1 = (v1 * m1) + (v2 * m2);
var c2 = (v1 * v1 * m1) + (v2 * v2 * m2);
var A = (m2 * m2) + (m2 * m1);
var B = -2 * m2 * c1;
var C = (c1 * c1) - (c2 * m1);
double vf2;
if (A != 0)
{
// b^2 - 4acS
var D = (B * B) - (4 * A * C);
if (D >= 0)
{
var vf2_plus = (-B + Math.Sqrt(D)) / (2 * A);
var vf2_minus = (-B - Math.Sqrt(D)) / (2 * A);
if (IsGood(vf2_minus, v2) && IsGood(vf2_plus, v2) && vf2_plus != vf2_minus)
{
if (Math.Abs(v2 - vf2_plus) > Math.Abs(v2 - vf2_minus))
{
if (Math.Abs(v2 - vf2_minus) > CLOSE)
{
throw new Exception("we are getting physicsObject2 vf2s: " + vf2_plus + "," + vf2_minus + " for vi2: " + v2);
}
vf2 = vf2_plus;
}
else
{
if (Math.Abs(v2 - vf2_plus) > CLOSE)
{
throw new Exception("we are getting physicsObject2 vf2s: " + vf2_plus + "," + vf2_minus + " for vi2: " + v2);
}
vf2 = vf2_minus;
}
}
else if (IsGood(vf2_minus, v2))
{
vf2 = vf2_minus;
}
else if (IsGood(vf2_plus, v2))
{
vf2 = vf2_plus;
}
else
{
throw new Exception("we are getting no vfs");
}
}
else
{
throw new Exception("should not be negative");
}
}
else
{
throw new Exception("A should not be 0! if A is zer something has 0 mass");
}
physicsObject2.Velocity = normal.NewScaled(vf2).NewAdded(normal.NewScaled(-v2)).NewAdded(physicsObject2.Velocity);
var f = (vf2 - v2) * m2;
var vf1 = v1 - (f / m1);
physicsObject1.Velocity = normal.NewScaled(vf1).NewAdded(normal.NewScaled(-v1)).NewAdded(physicsObject1.Velocity);
res = new MightBeCollision(new Collision(
physicsObject2.X + normal.NewScaled((physicsObject2 as PhysicsObject <Ball>).shape.Radius).x,
physicsObject2.Y + normal.NewScaled((physicsObject2 as PhysicsObject <Ball>).shape.Radius).y,
normal.NewScaled(vf1).x,
normal.NewScaled(vf1).y,
false
));
}
WhatHappensNext(physicsObject1, gridManager, eventManager, endTime);
WhatHappensNext(physicsObject2, gridManager, eventManager, endTime);
return(res);
}
