public void DrawPolygon(Vector2[] points, Color fillColor)
{
int numVertices = points.Length;
if (numVertices < 3)
{
return;
}
int numTriangles = numVertices - 2;
int i, restIndexPos, numRestIndices;
int k = 0;
Alloc(numVertices);
for (i = 0; i < numVertices; i++)
{
vertices[i] = new Vector3(points[i].x, -points[i].y);
}
// Algorithm "Ear clipping method" described here:
// -> https://en.wikipedia.org/wiki/Polygon_triangulation
//
// Implementation inspired by:
// -> http://polyk.ivank.net
// -> Starling
AllocTriangleArray(numTriangles * 3);
sRestIndices.Clear();
for (i = 0; i < numVertices; ++i)
{
sRestIndices.Add(i);
}
restIndexPos = 0;
numRestIndices = numVertices;
Vector2 a, b, c, p;
int otherIndex;
bool earFound;
int i0, i1, i2;
while (numRestIndices > 3)
{
earFound = false;
i0 = sRestIndices[restIndexPos % numRestIndices];
i1 = sRestIndices[(restIndexPos + 1) % numRestIndices];
i2 = sRestIndices[(restIndexPos + 2) % numRestIndices];
a = points[i0];
b = points[i1];
c = points[i2];
if ((a.y - b.y) * (c.x - b.x) + (b.x - a.x) * (c.y - b.y) >= 0)
{
earFound = true;
for (i = 3; i < numRestIndices; ++i)
{
otherIndex = sRestIndices[(restIndexPos + i) % numRestIndices];
p = points[otherIndex];
if (ToolSet.IsPointInTriangle(ref p, ref a, ref b, ref c))
{
earFound = false;
break;
}
}
}
if (earFound)
{
triangles[k++] = i0;
triangles[k++] = i1;
triangles[k++] = i2;
sRestIndices.RemoveAt((restIndexPos + 1) % numRestIndices);
numRestIndices--;
restIndexPos = 0;
}
else
{
restIndexPos++;
if (restIndexPos == numRestIndices)
{
break; // no more ears
}
}
}
triangles[k++] = sRestIndices[0];
triangles[k++] = sRestIndices[1];
triangles[k++] = sRestIndices[2];
FillColors(fillColor);
UpdateMesh();
}
