public bool Intersects(Triangle2D otherTriangle)
{
return
(Math2d.CheckLinesIntersect(this.V1, this.V2, otherTriangle.V1, otherTriangle.V2) ||
Math2d.CheckLinesIntersect(this.V1, this.V2, otherTriangle.V2, otherTriangle.V3) ||
Math2d.CheckLinesIntersect(this.V1, this.V2, otherTriangle.V3, otherTriangle.V1) ||
Math2d.CheckLinesIntersect(this.V2, this.V3, otherTriangle.V1, otherTriangle.V2) ||
Math2d.CheckLinesIntersect(this.V2, this.V3, otherTriangle.V2, otherTriangle.V3) ||
Math2d.CheckLinesIntersect(this.V2, this.V3, otherTriangle.V3, otherTriangle.V1) ||
Math2d.CheckLinesIntersect(this.V3, this.V1, otherTriangle.V1, otherTriangle.V2) ||
Math2d.CheckLinesIntersect(this.V3, this.V1, otherTriangle.V2, otherTriangle.V3) ||
Math2d.CheckLinesIntersect(this.V3, this.V1, otherTriangle.V3, otherTriangle.V1));
}
// !!! Does not work currently !!!
public IEnumerable <Triangle2D> Without(Triangle2D triangle)
{
var points1 = this.ToEnumerable().ToArray();
var points2 = triangle.ToEnumerable().ToArray();
var points = this.ToEnumerable().Concat(triangle.ToEnumerable()).ToList();
var indices1 = new List <int>(new int[] { 0, 1, 2 });
var indices2 = new List <int>(new int[] { 3, 4, 5 });
// Find all intersections between edges
for (int i = 0; i < 3; i++)
{
for (int j = 0; j < 3; j++)
{
if (Math2d.CheckLinesIntersect(points1[i], points2[(i + 1) % 3], points2[j], points2[(j + 1) % 3]))
{
var intersect = Math2d.LineLineIntersection(points1[i], points2[(i + 1) % 3], points2[j], points2[(j + 1) % 3]);
points.Add(intersect);
indices1.Add(points.Count - 1);
indices2.Add(points.Count - 1);
}
}
}
if (points.Count == 6) // No intersections found
{
if (triangle.Contains(points1[0]))
{
// This triangle is contained in the other one, result is empty
yield break;
}
else if (this.Contains(points2[0]))
{
// Other triangle is contained in this one
// TODO
yield break;
}
else
{
// Triangles don't touch each other
yield return(this);
yield break;
}
}
// Make indices clockwise
var center1 = (points1[0] + points1[1] + points1[2]) / 3.0f;
var center2 = (points2[0] + points2[1] + points2[2]) / 3.0f;
indices1.Sort((i, j) => getAngle(center1, points[i]).CompareTo(getAngle(center1, points[j])));
indices2.Sort((i, j) => getAngle(center2, points[i]).CompareTo(getAngle(center2, points[j])));
// Find polygons and triangulate
var visited = new bool[3];
for (int i = 0; i < 3; i++)
{
if (triangle.Contains(points[i]) || visited[i])
{
continue;
}
int indices1position = indices1.IndexOf(i);
var polygon = new List <int>();
while (true)
{
indices1position = (indices1position + 1) % indices1.Count;
int polygonIndex = indices1[indices1position];
polygon.Add(polygonIndex);
if (polygonIndex == i)
{
break;
}
if (polygonIndex < 3)
{
visited[polygonIndex] = true;
}
if (indices2.Contains(polygonIndex))
{
int indices2position = indices2.IndexOf(polygonIndex);
while (true)
{
indices2position = (indices2position - 1 + indices2.Count) % indices2.Count;
polygonIndex = indices2[indices2position];
polygon.Add(polygonIndex);
if (indices1.Contains(polygonIndex))
{
indices1position = indices1.IndexOf(polygonIndex);
break;
}
}
}
}
foreach (var t in Triangle2D.Triangulate(polygon.Select(p => points[p]).ToArray()))
{
yield return(t);
}
}
}
