private static void InWhichOrderAreVerticesAdded(List <ClipVertex> polyList)
{
ClipVertex thisVertex = polyList[0];
float size = 0.01f;
int safety = 0;
while (true)
{
Gizmos.color = Color.red;
//Gizmos.DrawWireSphere(new Vector3(thisVertex.coordinate.x, 0f, thisVertex.coordinate.y), size);
size += 0.01f;
thisVertex = thisVertex.next;
//We are back at the first vertex
if (thisVertex.Equals(polyList[0]))
{
break;
}
safety += 1;
if (safety > 100000)
{
Debug.Log("Endless loop in debug in which orders are vertices added");
break;
}
}
}
//
// Debug
//
private static void DebugEntryExit(List <ClipVertex> polyList)
{
ClipVertex thisVertex = polyList[0];
Gizmos.color = Color.green;
//Gizmos.DrawWireSphere(new Vector3(thisVertex.coordinate.x, 0f, thisVertex.coordinate.y), 0.1f);
float size = 0.02f;
int safety = 0;
while (true)
{
if (thisVertex.isIntersection)
{
//Gizmos.color = Color.white;
//Debug.Log(thisVertex.neighbor);
//Gizmos.DrawWireSphere(new Vector3(thisVertex.neighbor.coordinate.x, 0f, thisVertex.neighbor.coordinate.y), 0.05f);
Gizmos.color = Color.yellow;
if (thisVertex.isEntry)
{
//Gizmos.color = Color.white;
//Gizmos.DrawWireSphere(new Vector3(thisVertex.next.coordinate.x, 0f, thisVertex.next.coordinate.y), 0.04f);
Gizmos.color = Color.red;
}
//Gizmos.DrawWireSphere(new Vector3(thisVertex.coordinate.x, 0f, thisVertex.coordinate.y), size);
size += 0.005f;
}
thisVertex = thisVertex.next;
//We are back at the first vertex
if (thisVertex.Equals(polyList[0]))
{
break;
}
safety += 1;
if (safety > 100000)
{
Debug.Log("Endless loop in debug entry exit");
break;
}
}
}
//Insert intersection vertex
private static ClipVertex InsertIntersectionVertex(MyVector2 a, MyVector2 b, MyVector2 intersectionPoint, ClipVertex currentVertex)
{
//Calculate alpha which is how far the intersection coordinate is between a and b
//so we can insert this vertex at the correct position
//pos = start + dir * alpha
float alpha = MyVector2.SqrMagnitude(a - intersectionPoint) / MyVector2.SqrMagnitude(a - b);
//Debug.Log(alpha);
//Create a new vertex
ClipVertex intersectionVertex = new ClipVertex(intersectionPoint);
intersectionVertex.isIntersection = true;
intersectionVertex.alpha = alpha;
//Now we need to insert this intersection point somewhere after currentVertex
ClipVertex insertAfterThisVertex = currentVertex;
int safety = 0;
while (true)
{
//If the next vertex is an intersectionvertex with a higher alpha
//or if the next vertex is not an intersectionvertex, we cant improve, so break
if (insertAfterThisVertex.next.alpha > alpha || !insertAfterThisVertex.next.isIntersection)
{
break;
}
insertAfterThisVertex = insertAfterThisVertex.next;
safety += 1;
if (safety > 100000)
{
Debug.Log("Stuck in loop in insert intersection vertices");
break;
}
}
//Connect the vertex to the surrounding vertices
intersectionVertex.next = insertAfterThisVertex.next;
intersectionVertex.prev = insertAfterThisVertex;
insertAfterThisVertex.next.prev = intersectionVertex;
insertAfterThisVertex.next = intersectionVertex;
return(intersectionVertex);
}
//Mark entry exit points
private static void MarkEntryExit(List <ClipVertex> poly, List <MyVector2> clipPolyVector)
{
//First see if the first vertex starts inside or outside (we can use the original list)
bool isInside = _Intersections.PointPolygon(clipPolyVector, poly[0].coordinate);
//Debug.Log(isInside);
ClipVertex currentVertex = poly[0];
ClipVertex firstVertex = currentVertex;
int safety = 0;
while (true)
{
if (currentVertex.isIntersection)
{
//If we were outside, this is an entry
currentVertex.isEntry = isInside ? false : true;
//Now we know we are either inside or outside
isInside = !isInside;
}
currentVertex = currentVertex.next;
//We have travelled around the entire polygon
if (currentVertex.Equals(firstVertex))
{
break;
}
safety += 1;
if (safety > 100000)
{
Debug.Log("Endless loop in mark entry exit");
break;
}
}
}
//Find the the first entry vertex in a polygon
private static ClipVertex FindFirstEntryVertex(List <ClipVertex> poly)
{
ClipVertex thisVertex = poly[0];
ClipVertex firstVertex = thisVertex;
int safety = 0;
while (true)
{
//Is this an available entry vertex?
if (thisVertex.isIntersection && thisVertex.isEntry && !thisVertex.isTakenByFinalPolygon)
{
//We have found the first vertex
break;
}
thisVertex = thisVertex.next;
//We have travelled the entire polygon without finding an available entry vertex
if (thisVertex.Equals(firstVertex))
{
thisVertex = null;
break;
}
safety += 1;
if (safety > 100000)
{
Debug.Log("Endless loop in find first entry vertex");
break;
}
}
return(thisVertex);
}
//We may end up with several polygons, so this will split the connected list into one list per polygon
private static void AddPolygonToList(List <ClipVertex> verticesToAdd, List <List <MyVector2> > finalPoly, bool shouldReverse)
{
List <MyVector2> thisPolyList = new List <MyVector2>();
finalPoly.Add(thisPolyList);
for (int i = 0; i < verticesToAdd.Count; i++)
{
ClipVertex v = verticesToAdd[i];
thisPolyList.Add(v.coordinate);
//Have we found a new polygon?
if (v.nextPoly != null)
{
//If we are finding the !intersection, the vertices will be clockwise
//so we should reverse the list to make it easier to triangulate
if (shouldReverse)
{
thisPolyList.Reverse();
}
thisPolyList = new List <MyVector2>();
finalPoly.Add(thisPolyList);
//Debug.Log("test");
}
//Debug.Log(v.nextPoly);
}
//Reverse the last list added
if (shouldReverse)
{
finalPoly[finalPoly.Count - 1].Reverse();
}
}
//Reset vertices before we find the final polygon(s)
private static void ResetVertices(List <ClipVertex> poly)
{
ClipVertex resetVertex = poly[0];
int safety = 0;
while (true)
{
//Reset
resetVertex.isTakenByFinalPolygon = false;
resetVertex.nextPoly = null;
//Dont forget to reset the neighbor
if (resetVertex.isIntersection)
{
resetVertex.neighbor.isTakenByFinalPolygon = false;
}
resetVertex = resetVertex.next;
//All vertices are reset
if (resetVertex.Equals(poly[0]))
{
break;
}
safety += 1;
if (safety > 100000)
{
Debug.Log("Endless loop in reset vertices");
break;
}
}
}
//Get the clipped polygons: either the intersection or the !intersection
//We might end up with more than one polygon and they are connected via clipvertex nextpoly
//To get the intersection, we should
//Traverese the polygon until an intersection is encountered. Add this intersection to the clipped polygon.
//Traversal direction is determined by the entry/exit bool.
// - If the intersection is an entry, move forward along the current polygon
// - If the intersection is an exit, then change polygon, proceed in the backward direction of the other polygon
// - Change polygon if a new intersection is found
//If we want to the !intersection, we just travel in the reverse direction from the first intersection vertex
private static List <ClipVertex> GetClippedPolygon(List <ClipVertex> poly, bool getIntersectionPolygon)
{
List <ClipVertex> finalPolygon = new List <ClipVertex>();
//First we have to reset in case we are repeating this method several times depending on the type of boolean operation
ResetVertices(poly);
//Find the first intersection point which is always where we start
ClipVertex thisVertex = FindFirstEntryVertex(poly);
//Save this so we know when to stop the algortihm
ClipVertex firstVertex = thisVertex;
finalPolygon.Add(thisVertex);
thisVertex.isTakenByFinalPolygon = true;
thisVertex.neighbor.isTakenByFinalPolygon = true;
//These rows is the only part thats different if we want to get the intersection or the !intersection
//Are needed once again if there are more than one polygon
bool isMovingForward = getIntersectionPolygon ? true : false;
thisVertex = getIntersectionPolygon ? thisVertex.next : thisVertex.prev;
int safety = 0;
while (true)
{
if (thisVertex.Equals(firstVertex) || (thisVertex.neighbor != null && thisVertex.neighbor.Equals(firstVertex)))
{
//Debug.Log("Found a polygon with: " + finalPolygon.Count + " vertices");
//Debug.Log("Intersection vertices: " + intersectionVertices.Count);
//Try to find the next intersection point in case we end up with more than one polygon
ClipVertex nextVertex = FindFirstEntryVertex(poly);
//Stop if we are out of intersection vertices
if (nextVertex == null)
{
//Debug.Log("No more polygons can be found");
break;
}
//Find an entry vertex and start over with another polygon
else
{
//Debug.Log("Find another polygon");
//Debug.Log(thisVertex.nextPoly);
//Need to connect the polygons
finalPolygon[finalPolygon.Count - 1].nextPoly = nextVertex;
//Change to a new polygon
thisVertex = nextVertex;
firstVertex = nextVertex;
finalPolygon.Add(thisVertex);
thisVertex.isTakenByFinalPolygon = true;
thisVertex.neighbor.isTakenByFinalPolygon = true;
//Do we want to get the intersection or the !intersection
isMovingForward = getIntersectionPolygon ? true : false;
thisVertex = getIntersectionPolygon ? thisVertex.next : thisVertex.prev;
}
}
//If this is not an intersection, then just add it
if (!thisVertex.isIntersection)
{
finalPolygon.Add(thisVertex);
//And move in the direction we are moving
thisVertex = isMovingForward ? thisVertex.next : thisVertex.prev;
}
else
{
thisVertex.isTakenByFinalPolygon = true;
thisVertex.neighbor.isTakenByFinalPolygon = true;
//Jump to the other polygon
thisVertex = thisVertex.neighbor;
finalPolygon.Add(thisVertex);
//Move forward/ back depending on if this is an entry / exit vertex and if we want to find the intersection or not
if (getIntersectionPolygon)
{
isMovingForward = thisVertex.isEntry ? true : false;
thisVertex = thisVertex.isEntry ? thisVertex.next : thisVertex.prev;
}
else
{
isMovingForward = !isMovingForward;
thisVertex = isMovingForward ? thisVertex.next : thisVertex.prev;
}
}
safety += 1;
if (safety > 100000)
{
Debug.Log("Endless loop when creating clipped polygon");
//Debug.Log(isMovingForward);
break;
}
}
//Debug
//float size = 0.02f;
//for (int i = 0; i < finalPolygon.Count; i++)
//{
// int iMinusOne = MathUtility.ClampListIndex(i - 1, finalPolygon.Count);
// Vector3 v1 = new Vector3(finalPolygon[i].coordinate.x, 0f, finalPolygon[i].coordinate.y);
// Vector3 v2 = new Vector3(finalPolygon[iMinusOne].coordinate.x, 0f, finalPolygon[iMinusOne].coordinate.y);
// Gizmos.color = Color.white;
// Gizmos.DrawWireSphere(v1, size);
// Gizmos.DrawLine(v1, v2);
// size += 0.005f;
//}
//Debug.Log(finalPolygon.Count);
return(finalPolygon);
}
public static List <List <MyVector2> > ClipPolygons(List <MyVector2> polyVector2, List <MyVector2> clipPolyVector2, BooleanOperation booleanOperation)
{
List <List <MyVector2> > finalPoly = new List <List <MyVector2> >();
//Step 0. Create the data structure needed
List <ClipVertex> poly = InitDataStructure(polyVector2);
List <ClipVertex> clipPoly = InitDataStructure(clipPolyVector2);
//Step 1. Find intersection points
//Need to test if we have found an intersection point,
//if none is found, the polygons dont intersect, or one polygon is inside the other
bool hasFoundIntersection = false;
for (int i = 0; i < poly.Count; i++)
{
ClipVertex currentVertex = poly[i];
//Important to use iPlusOne because poly.next may change
int iPlusOne = MathUtility.ClampListIndex(i + 1, poly.Count);
MyVector2 a = poly[i].coordinate;
MyVector2 b = poly[iPlusOne].coordinate;
//Gizmos.DrawWireSphere(poly[i].coordinate, 0.02f);
//Gizmos.DrawWireSphere(poly[i].next.coordinate, 0.02f);
for (int j = 0; j < clipPoly.Count; j++)
{
int jPlusOne = MathUtility.ClampListIndex(j + 1, clipPoly.Count);
MyVector2 c = clipPoly[j].coordinate;
MyVector2 d = clipPoly[jPlusOne].coordinate;
//Are these lines intersecting?
if (_Intersections.LineLine(a, b, c, d, true))
{
hasFoundIntersection = true;
MyVector2 intersectionPoint2D = _Intersections.GetLineLineIntersectionPoint(a, b, c, d);
//Vector3 intersectionPoint = new Vector3(intersectionPoint2D.x, 0f, intersectionPoint2D.y);
//Gizmos.color = Color.red;
//Gizmos.DrawWireSphere(intersectionPoint, 0.04f);
//We need to insert this intersection vertex into both polygons
//Insert into the polygon
ClipVertex vertexOnPolygon = InsertIntersectionVertex(a, b, intersectionPoint2D, currentVertex);
//Insert into the clip polygon
ClipVertex vertexOnClipPolygon = InsertIntersectionVertex(c, d, intersectionPoint2D, clipPoly[j]);
//Also connect the intersection vertices with each other
vertexOnPolygon.neighbor = vertexOnClipPolygon;
vertexOnClipPolygon.neighbor = vertexOnPolygon;
}
}
}
//Debug in which order the vertices are in the linked list
//InWhichOrderAreVerticesAdded(poly);
//InWhichOrderAreVerticesAdded(clipPoly);
//If the polygons are intersecting
if (hasFoundIntersection)
{
//Step 2. Trace each polygon and mark entry and exit points to the other polygon's interior
MarkEntryExit(poly, clipPolyVector2);
MarkEntryExit(clipPoly, polyVector2);
//Debug entry exit points
DebugEntryExit(poly);
//DebugEntryExit(clipPoly);
//Step 3. Create the desired clipped polygon
if (booleanOperation == BooleanOperation.Intersection)
{
//Where the two polygons intersect
List <ClipVertex> intersectionVertices = GetClippedPolygon(poly, true);
//Debug.Log(intersectionVertices.Count);
AddPolygonToList(intersectionVertices, finalPoly, false);
//Debug.Log();
}
else if (booleanOperation == BooleanOperation.Difference)
{
//Whats outside of the polygon that doesnt intersect
List <ClipVertex> outsidePolyVertices = GetClippedPolygon(poly, false);
AddPolygonToList(outsidePolyVertices, finalPoly, true);
}
else if (booleanOperation == BooleanOperation.ExclusiveOr)
{
//Whats outside of the polygon that doesnt intersect
List <ClipVertex> outsidePolyVertices = GetClippedPolygon(poly, false);
AddPolygonToList(outsidePolyVertices, finalPoly, true);
//Whats outside of the polygon that doesnt intersect
List <ClipVertex> outsideClipPolyVertices = GetClippedPolygon(clipPoly, false);
AddPolygonToList(outsideClipPolyVertices, finalPoly, true);
}
else if (booleanOperation == BooleanOperation.Union)
{
//Where the two polygons intersect
List <ClipVertex> intersectionVertices = GetClippedPolygon(poly, true);
AddPolygonToList(intersectionVertices, finalPoly, false);
//Whats outside of the polygon that doesnt intersect
List <ClipVertex> outsidePolyVertices = GetClippedPolygon(poly, false);
AddPolygonToList(outsidePolyVertices, finalPoly, true);
//Whats outside of the polygon that doesnt intersect
List <ClipVertex> outsideClipPolyVertices = GetClippedPolygon(clipPoly, false);
AddPolygonToList(outsideClipPolyVertices, finalPoly, true);
}
//Where the two polygons intersect
//List<ClipVertex> intersectionVertices = GetClippedPolygon(poly, true);
//Whats outside of the polygon that doesnt intersect
//These will be in clockwise order so remember to change to counter clockwise
//List<ClipVertex> outsidePolyVertices = GetClippedPolygon(poly, false);
//List<ClipVertex> outsideClipPolyVertices = GetClippedPolygon(clipPoly, false);
}
//Check if one polygon is inside the other
else
{
//Is the polygon inside the clip polygon?
//Depending on the type of boolean operation, we might get a hole
if (IsPolygonInsidePolygon(polyVector2, clipPolyVector2))
{
Debug.Log("Poly is inside clip poly");
}
else if (IsPolygonInsidePolygon(clipPolyVector2, polyVector2))
{
Debug.Log("Clip poly is inside poly");
}
else
{
Debug.Log("Polygons are not intersecting");
}
}
return(finalPoly);
}
