public static bool CheckCollision(Shape shape1, Shape shape2)
{
// return true if collision has occured
List<Vector2> shape1axes = shape1.GetAxes();
List<Vector2> shape2axes = shape2.GetAxes();
foreach (Vector2 axis in shape1axes)
{
if (objectsSperarated(axis, shape1,shape2))
return false;
}
foreach (Vector2 axis in shape2axes)
{
if (objectsSperarated(axis, shape2, shape1))
return false;
}
return true;
}
static bool objectsSperarated(Vector2 axis, Shape shape1, Shape shape2)
{
//return true if there is a gap between the objects when projected onto axis
float min1 = float.MaxValue;
float max1 = float.MinValue;
float min2 = float.MaxValue;
float max2 = float.MinValue;
foreach(Vector2 point in shape1._points)
{// project this object on to axis
float proj=Vector2.Dot(axis,shape1._position+point);
if(proj<min1)min1=proj;
if(proj>max1)max1=proj;
}
foreach (Vector2 point in shape2._points)
{// project other object onto axis
float proj=Vector2.Dot(axis,shape2._position+point);
if(proj>min1 && proj<max1)// point lies inside other object's projection
return false;
if (proj < min2) min2 = proj;
if (proj > max2) max2 = proj;
}
//check if projection of first object completely inside of projection of 2nd object
if(min1>min2 && min1<max2)
return false;
return true;
}
internal static void bounce(Shape shape1, Shape shape2)
{
Vector2 displacement = shape1._position - shape2._position;
Vector2 closingspeed = shape1._velocity - shape2._velocity;
//check if they are already moving apart
if(Vector2.Dot(displacement,closingspeed)>=0){
return;// if moving apart, do nothing
}
displacement.Normalize();
Vector2 bounce;
//reverse the velocity vector in the direction of displacement
bounce= Vector2.Dot(shape1._velocity, displacement) * displacement;
shape1._velocity -= 2 * bounce;
bounce = Vector2.Dot(shape2._velocity, displacement) * displacement;
shape2._velocity -= 2 * bounce;
}