static bool generatingClockwisePolygon; // assigned in GenPolygonMesh, used by EarClipPoint
public static void GenPolygonMesh(Mesh mesh, List <Vector2> path, PolygonTriangulation triangulation)
{
// kinda have to do this, the algorithm relies on knowing this
generatingClockwisePolygon = ShapesMath.PolygonSignedArea(path) > 0;
mesh.Clear(); // todo maybe not always do this you know?
int pointCount = path.Count;
if (pointCount < 2)
{
return;
}
int triangleCount = pointCount - 2;
int triangleIndexCount = triangleCount * 3;
int[] meshTriangles = new int[triangleIndexCount];
if (triangulation == PolygonTriangulation.FastConvexOnly)
{
int tri = 0;
for (int i = 0; i < triangleCount; i++)
{
meshTriangles[tri++] = i + 2;
meshTriangles[tri++] = i + 1;
meshTriangles[tri++] = 0;
}
}
else
{
List <EarClipPoint> pointsLeft = new List <EarClipPoint>(pointCount);
for (int i = 0; i < pointCount; i++)
{
pointsLeft.Add(new EarClipPoint(i, new Vector2(path[i].x, path[i].y)));
}
for (int i = 0; i < pointCount; i++) // update prev/next connections
{
EarClipPoint p = pointsLeft[i];
p.prev = pointsLeft[(i + pointCount - 1) % pointCount];
p.next = pointsLeft[(i + 1) % pointCount];
}
int tri = 0;
int countLeft;
int safeguard = 1000000;
while ((countLeft = pointsLeft.Count) >= 3 && (safeguard-- > 0))
{
//for( int k = 0; k < pointsLeft.Count * 2; k++ ) {
if (countLeft == 3)
{
// final triangle
meshTriangles[tri++] = pointsLeft[2].vertIndex;
meshTriangles[tri++] = pointsLeft[1].vertIndex;
meshTriangles[tri++] = pointsLeft[0].vertIndex;
break;
}
// iterate until we find a convex vertex
bool foundConvex = false;
for (int i = 0; i < countLeft; i++)
{
EarClipPoint p = pointsLeft[i];
if (p.ReflexState == ReflexState.Convex)
{
// it's convex! now make sure there are no reflex points inside
bool canClipEar = true;
int idPrev = (i + countLeft - 1) % countLeft;
int idNext = (i + 1) % countLeft;
for (int j = 0; j < countLeft; j++)
{
if (j == i)
{
continue; // skip self
}
if (j == idPrev)
{
continue; // skip next
}
if (j == idNext)
{
continue; // skip prev
}
if (pointsLeft[j].ReflexState == ReflexState.Reflex)
{
// found a reflex point, make sure it's outside the triangle
if (ShapesMath.PointInsideTriangle(p.next.pt, p.pt, p.prev.pt, pointsLeft[j].pt, 0f, -0.0001f, 0f))
{
canClipEar = false; // it's inside, rip
break;
}
}
}
if (canClipEar)
{
meshTriangles[tri++] = p.next.vertIndex;
meshTriangles[tri++] = p.vertIndex;
meshTriangles[tri++] = p.prev.vertIndex;
p.next.MarkReflexUnknown();
p.prev.MarkReflexUnknown();
(p.next.prev, p.prev.next) = (p.prev, p.next); // update prev/next
pointsLeft.RemoveAt(i);
foundConvex = true;
break; // stop search for more convex edges, restart loop
}
}
}
// no convex found??
if (foundConvex == false)
{
Debug.LogError("Invalid polygon triangulation - no convex edges found. Your polygon is likely self-intersecting");
goto breakBoth;
}
}
breakBoth:
if (safeguard < 1)
{
Debug.LogError("Polygon triangulation failed, please report a bug (Shapes/Report Bug) with this exact case included");
}
}
// assign to segments mesh
List <Vector3> verts3D = new List <Vector3>(pointCount);
for (int i = 0; i < pointCount; i++)
{
verts3D.Add(path[i]);
}
mesh.SetVertices(verts3D);
mesh.subMeshCount = 1;
mesh.SetTriangles(meshTriangles, 0);
}
