//
// Are two triangles intersecting in 2d space
//
public static bool TriangleTriangle2D(Triangle2 t1, Triangle2 t2, bool do_AABB_test)
{
bool isIntersecting = false;
//Step 0. AABB intersection which may speed up the algorithm if the triangles are far apart
if (do_AABB_test)
{
//Rectangle that covers t1
AABB2 r1 = new AABB2(t1.MinX(), t1.MaxX(), t1.MinY(), t1.MaxY());
//Rectangle that covers t2
AABB2 r2 = new AABB2(t2.MinX(), t2.MaxX(), t2.MinY(), t2.MaxY());
if (!AABB_AABB_2D(r1, r2))
{
return(false);
}
}
//Step 1. Line-line instersection
//Line 1 of t1 against all lines of t2
if (
LineLine(t1.p1, t1.p2, t2.p1, t2.p2, true) ||
LineLine(t1.p1, t1.p2, t2.p2, t2.p3, true) ||
LineLine(t1.p1, t1.p2, t2.p3, t2.p1, true)
)
{
isIntersecting = true;
}
//Line 2 of t1 against all lines of t2
else if (
LineLine(t1.p2, t1.p3, t2.p1, t2.p2, true) ||
LineLine(t1.p2, t1.p3, t2.p2, t2.p3, true) ||
LineLine(t1.p2, t1.p3, t2.p3, t2.p1, true)
)
{
isIntersecting = true;
}
//Line 3 of t1 against all lines of t2
else if (
LineLine(t1.p3, t1.p1, t2.p1, t2.p2, true) ||
LineLine(t1.p3, t1.p1, t2.p2, t2.p3, true) ||
LineLine(t1.p3, t1.p1, t2.p3, t2.p1, true)
)
{
isIntersecting = true;
}
//Now we can return if we are intersecting so we dont need to spend time testing something else
if (isIntersecting)
{
return(isIntersecting);
}
//Step 2. Point-in-triangle intersection
//We only need to test one corner from each triangle
//If this point is not in the triangle, then the other points can't be in the triangle, because if this point is outside
//and another point is inside, then the line between them would have been covered by step 1: line-line intersections test
if (PointTriangle(t2, t1.p1, true) || PointTriangle(t1, t2.p1, true))
{
isIntersecting = true;
}
return(isIntersecting);
}
