private Triangle GetTriangleAt(TriangleIndex tri)
{
var result = new Triangle {
a = Points[tri.a], b = Points[tri.b], c = Points[tri.c]
};
return(result);
}
private TriangleIndex GetTriangleIndex(int middleVertex)
{
var previous = middleVertex == 0 ? validCount - 1 : middleVertex - 1;
var next = middleVertex == validCount - 1 ? 0 : middleVertex + 1;
var result = new TriangleIndex {
a = previous, b = middleVertex, c = next
};
return(result);
}
private TriangleIndex LowestTri()
{
if (lowest != null)
{
return(lowest);
}
var lowestIndex = LowestVertex();
lowest = GetTriangleIndex(lowestIndex);
return(lowest);
}
private bool IsConvex(TriangleIndex tri)
{
//if (OrientCCW(middleVertex) * OrientCCW(LowestVertex()) > 0)
//not xor is same as above with lower cpu & mem footprint
if (!(OrientCCW(tri) ^ LowestCCWOrient()))
{
return(true);
}
return(false);
}
private bool IsEmpty(TriangleIndex tri)
{
var previous = tri.a;
var middleVertex = tri.b;
var next = tri.c;
var tsv = SignCCW(previous, middleVertex, next);
for (int i = 0; i < validCount; i++)
{
if (i == previous || i == middleVertex || i == next)
{
continue;
}
if (tsv * SignCCW(middleVertex, previous, i) >= 0 &&
tsv * SignCCW(previous, next, i) >= 0 &&
tsv * SignCCW(next, middleVertex, i) >= 0)
{
return(false);//vertex i is inside triangle with middle vertex at middleVertex
}
}
return(true);
}
private bool OrientCCW(TriangleIndex tri)
{
return(ccw(tri.a, tri.b, tri.c) > 0);
}
