/// <summary>
/// Modification of set subtract for vector space.
/// </summary>
/// <param name="pos"></param>
/// <param name="neg"></param>
/// <param name="intersec"></param>
/// <returns></returns>
public static List <CSGShape> VectorSetSubtract(List <CSGShape> pos, CSGShape neg, List <CSGShape> intersec = null)
{
//Look to set subtract algorithm for explinations
//The primary difference between this algorithm, and the set subtract algorithm, is that this algorithm passes on correct r values to the output
List <CSGShape> outputList = new List <CSGShape>();
Stack <CSGShape> workingStack = new Stack <CSGShape>(pos);
while (workingStack.Count > 0)
{
CSGShape current = workingStack.Pop();
int offendingIndex;
var status = CSGPhysics.CalcCollision2D(neg, current, out offendingIndex);
if (status == CSGPhysics.CollisionType.BEnclosedInA)
{
if (intersec != null)
{
current.rValue += neg.rValue;
intersec.Add(current);
}
}
else if (status != CSGPhysics.CollisionType.NotColliding)
{
IPoly inside, outside;
Divide(current, out inside, out outside, neg.GetPoint(offendingIndex), neg.GetSurfaceNormal(offendingIndex), (x, y) => x.Clone(y));
workingStack.Push(new CSGShape(inside, current.rValue));
workingStack.Push(new CSGShape(outside, current.rValue));
}
else
{
outputList.Add(current);
}
}
return(outputList);
}
/// <summary>
/// Preforms the set subtract operation with multiple pos and a single neg.
/// </summary>
/// <param name="pos"></param>
/// <param name="neg"></param>
/// <param name="constructor"></param>
/// <returns></returns>
public static List <IPoly> SetSubtract(IEnumerable <IPoly> pos, IPoly neg, Func <IPoly, IEnumerable <Vector3>, IPoly> constructor)
{
//set subtract algorithm
//this version works for only 1 negative poly, and is the basis for multiple polys
//append all positive polys to a working stack
//pop polys from the working stack and compare them to the neg poly
//if they intersect, split them, and push them on the working stack
//if they are enclosed, remove them from the working list
//if they aren't instersecting append them to the output stack
//continue until working stack is empty
//Initialization
List <IPoly> outputList = new List <IPoly>();
Stack <IPoly> workingStack = new Stack <IPoly>(pos);
//working stack loop
while (workingStack.Count > 0)
{
//initialization
IPoly current = workingStack.Pop();
int offendingIndex;
//detect collision status
var status = CSGPhysics.CalcCollision2D(neg, current, out offendingIndex);
//enclosed, just throw away polygon
if (status == CSGPhysics.CollisionType.BEnclosedInA)
{
continue;
}
//if colliding, divide the polygon and push them on the working stack
else if (status != CSGPhysics.CollisionType.NotColliding)
{
IPoly inside, outside;
Divide(current, out inside, out outside, neg.GetPoint(offendingIndex), neg.GetSurfaceNormal(offendingIndex), constructor);
workingStack.Push(inside);
workingStack.Push(outside);
}
//if not colliding, append to output list
else
{
outputList.Add(current);
}
}
return(outputList);
}