public int[][] ConvexFill(int[][] points)
{
// edge table
EdgeTable et = new EdgeTable();
int topx1 = -1, topx2 = -1, topy = -1;
for (int pIndex = 0, len = points.GetLength(0); pIndex < len; pIndex++)
{
int[] p1 = points[pIndex];
int[] p2 = points[pIndex + 1 >= len ? 0 : pIndex + 1];
if (p1[1] != p2[1])
{
int yMin = 0;
EdgeNode node = new EdgeNode();
if (p1[1] > p2[1])
{
yMin = p2[1];
node.yMax = p1[1];
node.xMin = p2[0];
}
else
{
yMin = p1[1];
node.yMax = p2[1];
node.xMin = p1[0];
}
node.m = (float)(p1[0] - p2[0]) / (p1[1] - p2[1]);
et.AddNode(yMin, node);
}
else
{
// 记录top horizontal edge
// 这种简单判断topEdge的方式只对Convex有效
if (p1[1] > topy)
{
topy = p1[1];
if (p1[0] > p2[0])
{
topx1 = p2[0];
topx2 = p1[0];
}
else
{
topx1 = p1[0];
topx2 = p2[0];
}
}
if (pIndex == len - 1 &&
topy < points[1][1])
{
topy = -1;
}
}
}
// active edge table
EdgeBucket aet = new EdgeBucket();
if (et.Count == 0)
{
return(null);
}
else
{
// loop
Queue <int[]> result = new Queue <int[]>();
while (et.Count > 0 || aet.Count > 0)
{
if (aet.Count == 0)
{
aet.yMin = et[0].yMin;
et[0].ForEach((EdgeNode each) => aet.AddNode(each));
et.RemoveAt(0);
}
else
{
if (et.Count > 0 &&
aet.yMin == et[0].yMin)
{
et[0].ForEach((EdgeNode each) => aet.AddNode(each));
et.RemoveAt(0);
}
}
for (int aIndex = aet.Count - 1; aIndex >= 0; aIndex--)
{
if (aet[aIndex].yMax <= aet.yMin)
{
aet.RemoveAt(aIndex);
}
}
for (int aIndex = 0; aIndex < aet.Count; aIndex++)
{
if (aIndex % 2 == 0 &&
aIndex < aet.Count - 1)
{
float left = aet[aIndex].xMin;
float right = aet[aIndex + 1].xMin;
if (topy == -1 || aet.yMin != topy || left >= topx2 || right <= topx1)
{
// 以上判断是为了排除top horizontal edge
int ileft = MathS.Floor(left);
int iright = MathS.Floor(right);
for (int ixMin = ileft; ixMin <= iright; ixMin += 1)
{
if (ixMin >= left && ixMin < right)
{
// 以上判断是为了排除像素点刚好在rightEdge的情况
result.Enqueue(new int[] { ixMin, aet.yMin });
}
}
}
aet[aIndex].xMin += aet[aIndex].m;
aet[aIndex + 1].xMin += aet[aIndex + 1].m;
if (aet[aIndex].xMin > aet[aIndex + 1].xMin)
{
EdgeNode temp = aet[aIndex];
aet[aIndex] = aet[aIndex + 1];
aet[aIndex + 1] = temp;
}
}
}
aet.yMin += 1;
}
return(result.ToArray());
}
}
