private void ClipTriangles(BaseMeshTriangle baseTri, MeshTriangle projTri, List <MeshPoint> outverts, List <int> inds)
{
//Sutherland–Hodgman algorithm
//clip a triangle against another by iteratively clipping each edge of the second one
//we want to clip against base tri
var outputList = new MeshPolygon(projTri);
var basePlane = new Plane(baseTri.Vertices[0], baseTri.Vertices[1], baseTri.Vertices[2]);
for (int i = 0; i < 3; i++)
{
if (outputList.Points.Count == 0)
{
return;
}
var inputList = outputList;
var edge = new ClipEdge(baseTri.Vertices[i], baseTri.Vertices[(i + 1) % 3]);
outputList = new MeshPolygon();
var lastPoint = inputList.Points.Last();
int j = inputList.Points.Count - 1;
foreach (var point in inputList.Points)
{
if (!edge.ShouldClip(point.Position))
{
if (edge.ShouldClip(lastPoint.Position))
{
outputList.Points.Add(edge.IntersectLine(inputList, j));
}
//we still need to project the point onto the surface...
var ray = new Ray(point.Position, new Vector3(0, -1, 0));
var intersect2 = ray.Intersects(basePlane);
if (intersect2 == null)
{
ray.Direction *= -1;
intersect2 = ray.Intersects(basePlane);
if (intersect2 == null)
{
}
intersect2 = -(intersect2 ?? 0f);
}
point.Position.Y -= intersect2.Value;
outputList.Points.Add(point);
}
else
{
if (!edge.ShouldClip(lastPoint.Position))
{
outputList.Points.Add(edge.IntersectLine(inputList, j));
}
}
j = (j + 1) % inputList.Points.Count;
lastPoint = point;
}
}
if (outputList.Points.Count < 3)
{
return; //?
}
outputList.Triangulate(outverts, inds);
}
public bool RoughIntersects(BaseMeshTriangle other)
{
return(!(x1 > other.x2 || x2 < other.x1 || y1 > other.y2 || y2 < other.y1));
}
